thesis submitted in partial fulfilment of the …effect of polymer coated urea on growth and yield...
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EFFECT OF POLYMER COATED UREA ON
GROWTH AND YIELD OF RICE (Oryza sativa L.)
THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS
FOR THE DEGREE OF
Master of Science (Agriculture)
in
Agronomy
DEPARTMENT OF AGRONOMY
INSTITUTE OF AGRICULTURAL SCIENCES BANARAS HINDU UNIVERSITY
VARANASI - 221 005
I D. No. : A-13006 2015 Enrolment No. : 359617
Supervisor
Prof. Avijit Sen Submitted by
Rajani Sirvi
HER
BIC
IDA
L E
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F [X
anth
ium
strum
ariu
m (L
.)] EXT
RA
CT
ON
W
EED
S O
F T
RA
NSPLA
NTED
RIC
E [O
ryza sa
tiva (L
.)]
M.Sc.
Pravin K
umar U
padhyay
2012
Dr. Avijit Sen Professor & Head Phone: 05426702415
Email: [email protected]
Department of Agronomy
Institute of Agricultural Sciences
Banaras Hindu University
Varanasi-221005
U.P. (INDIA)
Ref. No. ……………… Date: ..............
CERTIFICATE
To,
The Registrar (Academic)
Banaras Hindu University,
Varanasi- 221005 (India).
Through: The Head
Department of Agronomy
Institute of Agricultural Sciences
Banaras Hindu University,
Varanasi- 221005.
Dear Sir,
I have great pleasure in forwarding the thesis entitled “Effect of polymer coated
urea on growth and yield of rice (Oryza sativa L.).”submitted by Ms. Rajani Sirvi
(I.D. No. A-13006) in partial fulfilment of the requirements for the degree of MASTER
OF SCIENCE (Agriculture) in AGRONOMY, Institute of Agricultural Sciences,
Banaras Hindu University, Varanasi (U.P.) and placing on record that he has completed
the requisite residential requirements as contained in the statutes of the University.
I certify that the work has been carried out under my guidance and the data
forming the basis of this thesis, to the best of my knowledge are original and genuine and
no part of the work has been submitted for any other degree or dissertation.
Thanking you,
FORWARDED BY, Yours faithfully,
(Avijit Sen) Supervisor
EFFECT OF POLYMER COATED UREA ON GROWTH
AND YIELD OF RICE [Oryza sativa (L.)]
by
Rajani Sirvi
Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of
Master Of Science (Agriculture)
In
Agronomy
DEPARTMENT OF AGRONOMY
INSTITUTE OF AGRICULTURAL SCIENCES
BANARAS HINDU UNIVERSITY
VARANASI – 221005
2015
I.D. No.A-13006 Enrolment No.359617
APPROVED BY ADVISORY COMMITTEE
CHAIRMAN Dr. Avijit Sen Professor
Department of Agronomy, I.Ag.Sc., BHU.
MEMBERS Dr. Yashwant Singh Professor
Department of Agronomy, I.Ag.Sc., BHU.
Dr. Praveen Prakash
Associate Professor
Department of Plant Physiology,I.Ag.Sc., BHU.
EXTERNAL EXAMINER
Acknowledgement
I bow my head and offer flowers of reverence to Mahamana Pt. Madan Mohan Malviya, the Founder of Banaras Hindu University, for his life time sacrifice and efforts in establishing such a great temple of learning for the cause of millions of students like me.
It is exquisitely a jubilating occasion and unique opportunity to express my hearty indebtedness to my esteemed guide Prof. Avijit Sen, Head of Department, Department of Agronomy, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi. I feel extreme pleasure to owe my profound sense of gratitude and indebtedness for his scholastic guidance, perceptive criticism, affection and constant source of inspiration which enabled me to complete the task with great ease and will thus continue to occupy a prominent place in my memory.
I owe my sincere thanks to the members of my advisory committee, Prof. Yashwant Singh, Department of Agronomy and Dr. Praveen Prakash, Department of Plant Physiology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi (U.P.) for their critical suggestion, impeccable and benevolent guidance.
I am grateful to Dr. Praveen Prakash Department of Plant Physiology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi (U.P.) for extending all possible help in his laboratory during the course of this study.
I am highly obliged to Prof. Rajendra Prasad Singh, Former Head, Department of Agronomy for providing the necessary research and academic facilities during the course of investigation.
My special thanks to Mr. Nandu Ram Yadav, Mr. Vijay Pratap Singh, Mr. J.C.N.Tripathi and Mr. Shayam Sundar for whole hearted co-operation and continues inspiration.
With profound regards in a more personal sense, I owe deepest debts to my parents Shri Narayan Lal and Smt. Hastu Devi who taught me the value of wisdom based on erudition but without enslaved by it and their persistent inspiration, selfless sacrifice, continuous encouragement and blessing gave untiring help and have enabled me to be so today.
I am quite unable to find appropriate words as to express my deepest sense of gratitude to my beloved, my best friend Dharm Singh Meena, my beloved sister Rekha Sirvi, my brothers Mr. Ranveer Sirvi, Mr. Dinesh Sirvi and Mr. Shankar Lal Sirvi. It was their zeal and enthusiasm which made it possible for me to complete my logical end of this study. My words are too feeble to give my inner feelings. Their constant encouragement, moral and emotional support rendered throughout my education for which I will remain indebted to them throughout my life.
Without the help of seniors no one can learn the lesson of life and cannot teach the same to loving juniors so, heartfelt and special thanks to my seniors. Mr. Praveen Upadhyay , Mr. Anandi Lal Jat, Mr. Shyoji Lal Bairwa, Mr. Pradeep Singh, Mr. Santosh Kumar, Mr. Kanhaiya Lal Regar, Mr. Santosh Meena, Mr. Surya Pratap Singh, Miss Ekta Kumari, Miss Mona Nagargade, Mr. Visal Tyagi, Mr. Gorav and Rupesh Kumar Meena for their co-operation during the study and investigation.
The words are inadequate to express my feelings to my friends Kiran Hingonia, Mishan Das, Surajyoti Pradhan, Aurdit Sankar, Geetangali Singh, Ram Singh, Sandeep Sihag, Shivam Shukla, Shiv Bahadur, Lala Ram, Rajendra Prashad Meena, Gangadhar Nanda, Dharmendra Kumar and Chandra Shekar for their moral support, co-operation, priceless suggestions and their immense love and affection which always animated me to face the challenges and material support during the thesis work.
It is pleasure for me to give thanks to my lovely juniors Deshraj, Pooja Kumari, Twinkle, Swati and Dinesh Sirvi.
Before pen down, I once again confess that I do not know how to acknowledge the help and co-operation of my supervisor, members of advisory committee, family members and relatives, seniors, juniors, colleagues but above feeling are followed from the core of my heart in the shape of words and as gospel truth.
The graces of the God are always blessed to me and give me patience and power to overcome the difficulties which came my way in accomplishment of this endeavour. I cannot dare to say thanks but only pray to bless me always.
Above all, my humble and whole hearted prostration to Lord Baba Vishwanath, Sankat Mochan & Goddess Saraswati for their blessings.
Lastly, I bow at the feet of “Goddes Sarswati” with whose omnipresent blessing today on the eve of completion of my thesis. This is a long adventurous journey to the unknown destination with a hope for future. I was not alone in this journey to accomplish this Herculean task, and I am in a position to acknowledge all those, who helped me a lot to cross the way in finishing the marathon work.
Date: (Rajani Sirvi) Place: Varanasi Department of Agronomy
Institute of Agricultural Sciences, Banaras Hindu University, Varanasi-221005
CONTENTS
S. No. Chapters Page No.
1. Introduction 1-4
2. Review of Literature 5-21
3. Materials and Methods 22-37
4. Experimental Findings 38-46
5. Discussion 47-53
6. Summary and Conclusion 54-55
Bibliography i-vii
LIST OF TABLES
Table No. Particular Page No.
Table 3.1 Weekly meteorological data of Varanasi during experiment
period (June, 2014 to October, 2014) .................................................. 23
Table 3.2 Physico-chemical and mechanical analysis of experimental soil ........ 26
Table 3.3a Treatment details ................................................................................. 27
Table 3.3a Detail of layout .................................................................................... 27
Table 3.4 Schedule of field operations carried out during experiment ............... 31
Table 3.5 Method of chemical analysis of plant samples………………....…….36
After
Page No.
Table 4.1 Effect of different treatments on nitrogen content in soil at 3 days
intervals ………......................................................................……. 38
Table 4.2 Effect of different treatments on plant height...................................... 39
Table 4.3 Effect of different treatments on number of tillers .............................. 39
Table 4.4 Effect of coated urea on number of leaves ……………………......…40
Table 4.5 Effect of different treatments on chlorophyll content (SPAD) ...… 40
Table 4.6 Effect of different treatments on fresh and dry weight per hill at
harvest.……….......................................................................… 41
Table 4.7 Effect of different treatments on length and weight of panicle,
number of grain per panicle and test weight ................................... 43
Table 4.8 Effect of different treatment on grain, straw, total biological yield
and harvest index..............................................................................44
Table 4.9 Effect of coated urea on nitrogen, phosphorus and potassium
content in grain..................................................................................45
Table 4.10 Effect of coated urea on nitrogen, phosphorus and potassium
content in straw ................................................................................45
Table 4.11 Effect of different treatment on nutrient uptake by hill ....................... 46
Table 4.12 Effect of coated urea on protein content in grain ................................ 46
LIST OF FIGURES
Figure No. Particular After
Page No.
Fig. 3.1 Meteorological observations (Standard week wise) obtained
from the Meteorological observatory of the Banaras Hindu
University, during experimental period (2014) .................................. 24
Fig. 3.2 Layout of experimental field ............................................................... 27
Fig. 4.1 Effect of different treatments on nitrogen content in soil at 3
days intervals ....................................................................................... 38
Fig. 4.2 Effect of different treatments on plant height .................................... 39
Fig. 4.3 Effect of different treatments on number of tillers ............................ 39
Fig. 4.4 Effect of different treatments on chlorophyll content (SPAD) .......... 40
Fig. 4.5 Effect of different treatment on grain, straw, total biological
yield ..................................................................................................... 44
LIST OF PLATES
Plate No. Particular After
Page No.
Plate no. 1 Xanthium strumarium .......................................................................... 28
Plate no. 2 Soxhlet extraction unit ......................................................................... 32
Plate no. 3 Rotary evaporator ................................................................................ 32
Plate no. 4 Xanthium strumarium extract ready for use as herbicide .................... 45
Plate no. 5 Xanthium strumarium extract applied in field ..................................... 45
Abbreviations and Symbols Used
% Per cent
/ Per
@ At the rate
C.D. Critical difference
cm Centimeter
SEm± Standard error of mean
d.f. Degree of freedom
DAT Days after transplanting
dSm-1 Decisiemen per meter
e.g. For example
EC Electrical conductivity
et al. And others
Fig. Figure
ac acre
g Gram
ha Hectare oC Degree centigrade
hrs Hours
i.e. Id est (that is)
K Potassium
N Nitrogen
P2O5 Phosphorus
kg Kilogram
lb pound
m Meter
Max. Maximum
Min. Minimum
mm Millimeter
mt Million tones
N Nitrogen
No. Number
NS Non significant
pH Puissance de hydrogen
q Quintal
t Tonnes
viz. Namely
Chapter I
INTRODUCTION
Rice (Oryza sativa L.) is one of the major staple food crops for more than half
of the world population and is grown worldwide. It is a nutritious cereal crop which
provides 20 % of the calories and 15 % of protein consumed by world’s population,
besides minerals and fiber. The slogan ‘Rice is Life’ is most appropriate for India as
this crop plays a vital role in our national food security and a means of livelihood for
millions of rural household. In India, this crop is grown in 43.9 million hectare of land
with total annual production of 106.5 million tonnes with an average productivity of
24.24 q ha-1 (Anonymous, 2014).
Rice is most widely consumed in one or other form by poorest to richest
person in this world. However, rice is a poor source of essential micronutrients such
as Iron (Fe) and Zinc (Zn). The average content of protein in rice grains is 8 per cent,
iron 1.2 mg/100 g and zinc 0.5 mg/100 g.
To keep pace with demands of increasing populations, global rice production
needs to be increased significantly in the next 10 years. Rice production has to be
raised up to 160 million tonnes by 2030 with a minimum annual growth rate of 2.35
per cent to meet the increasing food demand. The possibility of expanding the area
under rice is limited. Therefore, this extra rice production needed has to come from a
productivity gain. The major challenge to achieve this gain lies with weed, labour and
chemical management of which will ensure long-term sustainability. Rice is mostly
grown in lowland area under wet condition usually associated with leaching, run-off,
volatilization and denitrification losses of most of applied nitrogen as fertilizer.
Nitrogen (N) plays a central role in modern agriculture. It is an essential
nutrient and also the major limiting factor in most agricultural soils under all agro-
ecological condition. Poor nutrient utilization and nitrogen losses from urea
applications have been reported for many years (Khalil et al., 2009). The N losses
from applied urea have been estimated to be 30 to 60 per cent in tropical soil (Freney
et al., 1981). Low recovery of N in annual crop is associated with its loss by
Introduction
~2~
volatilization, leaching, surface runoff, and denitrification. However, worldwide
recovery of N in cereal crops is usually 30-50 per cent (Ladha et al., 2005).
Rice utilizes conventionally broadcast nitrogenous fertilizers very
inefficiently. Mitsui (1954) estimated that rice commonly recovered only 30-40 per
cent of applied N, whereas upland crops recover 50-60 per cent. The other 60-70 per
cent of the N applied to rice is subject to gaseous losses through nitrification-
denitrification and ammonia volatilization, or to losses in water through leaching and
runoff (Broadbent 1978, 1979; Craswell and Vlek 1979). Bilal et al. (1979) and Lin
et al. (1975) reported field leaching losses of 4-30 per cent from ammonium sulfate;
whereas Rao (1977) reported 17 per cent loss from urea and up to 63 per cent losses
from added ammonium nitrogen (through denitrification) as measured from soils
undergoing short but frequent cycles of wetting and drying (Reddy and Patrick, 1975).
Nitrogen use efficiency of rice can be increased by reducing the solubility of
nitrogenous compound through physical or chemical methods. Physical methods
depend on coating or encapsulation of water soluble materials with outer layers of
organic or inorganic materials. Encapsulated materials are characterized by diffusion
controlled release of nutrients through the surface layer. Physical methods of control
include sulphur, polymer and mixed. sulphur- polymer encapsulated materials
(Oertli,1980; Booze-Daniels and Schmidt, 1997) and resin coatings (thermoset and
thermoplastic resins) such as osmocote (Hulme and Buchheit, 2007).
Chemical methods of control include conversion of nitrogen to polymeric
forms that have reduced water solubility like urea formaldehydes, isobutylidene
diurea (IBDU) and crotonylidene diurea (CDU). Other types of slow release and
controlled release formulations include gel forming materials, zeolite based materials
as also urease and nitrification inhibitors.
Controlled release fertilizer (CRF) is a purposely designed manure that
releases active fertilizing nutrients in a controlled, delayed manner in synchrony with
the sequential needs of plants for nutrients, by virtue of which it enhances nutrient use
efficiency along with more yields (Shaviv, 2005). An ideal controlled release fertilizer
is coated with a natural or semi-natural, environmental friendly macromolecule
Introduction
~3~
material that retards fertilizer releases to such a slow pace that a single application to
the soil can meet nutrient requirements for model crop growth.
Sulfur has been used to produce controlled release coated urea (CRCU) for
decades. Sulfur-coated urea, or SCU, fertilizers release nitrogen via water penetration
through cracks and micropores in the coating. Once water penetrates through the
coating, nitrogen release is rapid. Sulfur-coated products typically range from 32 to 41
per cent elemental nitrogen by weight. The sulfur coating process was originally
developed by the Tennessee Valley Authority.
A technique for coating urea with neem cake was developed at IARI, New
Delhi. The neem cake is coated on urea using a coal-tar kerosene mixture (Prasad
et al., 1999). Another technique of coating urea with neem oil micro-emulsion was
developed at IARI (Suri et al., 2000). Trials conducted by KRIBHCO showed that
neem emulsion coating was superior to prilled urea, extended the shelf life of urea,
helped in sustaining nitrogen in the soil for a very long time resulting in better yields
(Prasad et al., 2005, 2007).
Polymer coated urea is one such type of controlled release fertilizer, which
potentially keeps more N in the root zone, reduces N losses, improves nitrogen use
efficiency and reduces negative effect on the environment. The most promising for
widespread agricultural use are polymer coated urea which can be designed to release
nutrient in a controlled manner (Baligar, 2015).
Polyolefin-coated fertilizer (POCF) is one of the CRFs developed in Japan that
shows highly controlled nutrient-release characterized by temperature. This accurate
nutrient control enables large amount of PCU to be placed with seeds or seedlings
without salt damage (Kaneta et al., 2010).
A limited number of studies comparing polymer-coated urea with urea have
indicated crop yield can be higher, lower or unchanged depending on the crop and
environmental conditions during the growing season (Golden et al., 2009; Noelisch
et al., 2009; Blackshaw et al., 2011). Noellsch et al., (2009) studied the effects of
conventional and slow-release N fertilizer sources and landscape position on corn
(Zea mays L.) in a claypan soil. Anhydrous ammonia and PCU increased grain yield
Introduction
~4~
by 1470 to 1810 kg ha-1 over urea. Based on the grain yield and different fertilizer
cost and crop prices, gross profit differences for use of PCU and preplant-applied
anhydrous ammonia compared with urea in the low-lying position could range from
$50 to $642 ha-1.
Controlled release fertilizers not only increase the nutrient use efficiency but
also reduce cost of production and pollution hazards. The accurate nutrient control
enables large amount of PCU to be placed with seeds or seedlings without salt
damage (Kaneta et al., 2010). Hence present investigation entitled “Effect of polymer
coated urea on the growth and yield of rice [Oryza sativa (L.)]” was carried out
during Kharif season of 2014 at the Agricultural Research Farm of the Institute of
Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh the with
following specific objectives.
1. To find out nitrogen content in soil with deep placement of different coated
urea fertilizers like polymer coated urea, neem coated urea, sulphur coated
urea and urea supergranule.
2. To find out their effect on growth, yield and nutrient uptake by rice.
Chapter- II
Review of Literature
Rice (Oryza sativaL.), one of the most important cereals, is the premier food
crop not only in India but in world also and is grown extensively in tropical and sub-
tropical regions of the world. Rice is mostly cultivated in lowland area under wetland
condition usually associated with leaching, run-off, volatilization and denitrification
losses of most of the applied nitrogen as fertilizer and reduces use efficiency below
30%. For rice, nitrogen accounts for approximately 19-20% of total variable
production cost (Watkins et al., 2010).
Rice being an important food crop of the world has been studied by a large
number of research workers for different inputs and agro-techniques in various parts
of India and abroad. The present field trial was designed to find out the “Effect of
polymer coated urea on the growth and yield of rice (Oryza sativa L.)”. In this
chapter an attempt has been made to critically review the research works carried out
within the country and abroad on the context stated above.
2.1 Polymer coated urea (PCU)
Nowsher et al. (1988) reported that sulphur coated urea was superior to
conventional method of urea application and point placement of urea super granules at
higher nitrogen rates. At lower nitrogen rates, there were no significant responses.
Gandeza et al. (1991) and Zvomuya et al. (2003) reported that from Agrium
PCU (polymer coated urea) N release (97%) peaked between 135 and 140 days after
planting (DAP) and reached a plateau after this point. For Kingenta PCU (polymer
coated urea), %N release was found to be a linear function of DAP, the peak per cent
N release (%NR) had not been reached by the last sampling date.
An experiment on urea release from single granule in free water at 300 C
indicated that the release rate depended on size of granule, coating thickness and
water permeability (Shaviv et al., 2003). The rate of release was inversely
proportional to r × l2 andthe lag-period is proportional to the product of granule radius
Review of Literature
~ 6 ~
(r) and coating thickness (l) and inversely dependent on the driving force and the
water permeability.
Shaviv (2005) concluded that release rate was inversely dependant on the
product of granule radius (R0) and coating thickness (l).The release rate increased due
to a decrease in thickness (l) and radius (R0).
Kanno (2008) stated that N dissolution from polyolefin coated urea (POCU-30
and 70) was about 80% of the total N at around 40 and 90 days after sowing (DAS) in
1994, and 40 and 100 DAS in 1995, respectively . At the end of the growing season of
maize crop (112 DAS), POCU-30, POCU-70 and POCU-S60 had dissolved95, 86,
85% N in 1994 and 96, 83, 85% N in 1995, respectively. Therefore, the actual
fertilizer-N supply of the POCU-70 and POCU-30+S60 were 126-129 and 133 kg N
ha-1 respectively, and were lower than that of the urea (150 kg N ha-1).
Wilson et al. (2009) found that polymer-coated urea incubated in
polypropylene mesh pouches with 1.2 mm2 openings and 43% open area had
significantly greater N release than pouches made from weedblock material with 0.07
mm2 openings and 24% open area after 40days after planting (DAP), but initial
release rate was similar. The polypropylene mesh allowed prills to come in close to
the soil compared with weedblock bags and may explain the difference in per cent N
release (%NR).
Rosen et al. conducted an experiment in 2010 to compare differences in N
release rates and tuber yield and quality between dealer gradeEnvironmentally Smart
Nitrogen (ESN), potentially damaged ESN and stabilized N products. They observed
that N release from the airboom demaged ESN (A) was much more rapid than release
from a comparable application of dealer grade product – ESN (C). Sixty per cent of
the N had been released within 8 days after application of the air boom ESN
(ESN-A) which was 12% faster than the undamaged control ESN (ESN-C). In a
leaching year, therefore risk of losses would be minimized by using undamaged ESN.
Yi et al. (2011) found that the accumulation of NO3- -N in 0-100 cm soil layer
in all treatments ranged from 39.70-49.93 kg ha-1, and was the lowest with 39.70 kg
ha-1 in treatment PU4 (40% PCU60+60% U). The N release pattern of PCU-60 under
Review of Literature
~ 7 ~
field condition better fitted the N absorption characteristics of winter wheat that
minimize the risk of leaching losses.
Wang et al. (2011) observed that 100% N was released in about 220 hrs from
polymer coated urea (PCU) and polymer coated-NPK (PC- NPK) at 1000C in contrast
to at 25°C where only 63.6% to 70.8% N was released over a period of 220 days. At
100°C, per cent N release from polymer coated urea (PCU) was generally greater than
that from PC-NPK at any given time throughout the incubation but at 25°C, per cent
N release was greater from PCU than that from PC-NPK during first 100 days,
subsequently, the trend was reversed till the end of 216 days incubation period.
Trinh et al. (2014) observed that the release time proportionally depends on
the particle size. Release time and rate of release increases as particle size changes
from 1 to 4 mm. Diffusive flux was 2.04×10-6 mol/(m2.s) as coating thickness was
0.050 mm after which it decreased to 0.65×10-6 mol/(m2.s) with a 0.150 mm of
coating thickness. Release time also decreases due to an increase on coating thickness.
Release time with 0.1 mm coating was 76.85 days which is comparatively lower than
0.125 mm coating thickness with release time 93.75 days. The difference between two
thicknesses was 0.025 mm but release time increased 22%.
2.2 Effect of polymer coated urea (PCU) on growth attributes
A growth-chamber study showed that barley roots proliferated around polymer
coated urea granules, resulted in greater root mass and N uptake per unit of root
compared to a conventional urea (Zhang et al., 2000a, 2000b).
Schwab and Murdock conducted an experiment in 2003-04 to study the effect
of source × rate interaction or main effect of source on dry matter, grain yield as well
as plant N uptake in corn and observed a non-significant effect at both the locations
Lexington and Princeton. However, dry matter at the V6 growth stage was recorded
higher values for the polymer coated urea as compared to the ammonium nitrate (AN)
at the Princeton location. Dry matter increased as rate of N increased at both the
locations.
Review of Literature
~ 8 ~
Singh et al. (2004) stated that maximum dry matter accumulation in paddy
(excluding 30 DAT) took place with NPK + 75% pyrite + 25% polyolefin resin
coated slow release Fe (PRCSRFe) which was statistically superior to other sources
except NPK + 50% pyrite + 50% polyolefin resin coated slow release Fe (PRCSRFe).
Pack et al. (2007) revealed that there were no significant difference in leaf,
stem, or leaf + stem dry weights for potato with any of the treatments sampled at full
flower,indicated similar potato plant sizes. Though, tuber dry weights varied at
harvesting with different treatments viz.TRT-10 (146 kg ha−1 N; 133.9 g plant−1),
TRT-6 (146 kg ha−1N; 110.4 g plant−1), and TRT-14 (146 kg ha−1 N; 108.0 g plant−1)
being significantly higher than the No-N (82.3 g plant−1) treatment.
Sahota et al. (2010) revealed that ESN resulted in significantly higher dry
matter yield of timothy than urea and the effect increased with the increasing rates of
N application, from 0 to 105 kg ha-1, more or less linearly.
A study was conducted at nine-site in Alberta,Lethbridge to compare seed-
placed environmentally smart nitrogen (ESN) with seed-placed untreated urea on
stand establishment in canola. It was found that ESN applied at 136 pounds per acre
(60 pounds of actual nitrogen) could be safely applied in the seed row without any
injury to seed, seed germination and seedling establishment.
The result of an experiment conducted in china by Jan-gang et al. (2010)
showed that in plough layer, root length density of summer maize from polymer
coated fertilizer N (PCFN) at the rate of 120 &180 kg ha-1 N with co-situs placement
was comparatively higher near stem than those from conventional fertilizer (180 kg
ha-1 N) or no fertilized treatments. Approximately 59-64% of total root was distributed
in surface layer from 0-10 cm near the stem of maize plant.
Junejo et al. (2010) recorded that the application of coated urea increased dry
matter yield by 20 to 60% pot-1as compared to urea alone. Among all the treatments,
the highest dry matter yield (29.25 g pot-1) was obtained from gelatin Cu coated urea
and (26.50 g pot-1) micronutrient coated urea treated pots in maize. The uncoated urea
produced the least dry matter yield (19 g pot-1) at the same level of N application.
Review of Literature
~ 9 ~
Fageria (2011) revealed that root length and root dry weight were significantly
influenced by nitrogen fertilization in lowland rice. Polymer coated urea (PCU)
increased crop root growth, improved production of lateral roots and root hairs as well
as rooting depth and root density in the profile by increasing soil N availability for
longer time.
Nash et al. (2013) reported that broadcast and strip-till placement of polymer
coated urea (PCU) produced taller plants than the non-treated controls. Plant
population increased with PCU (8,400 plants ha-1) compared to no coated urea (8,100
plants ha-1) with both strip till and no-till placement.
Strey and Christians (2013) observed that Kentucky bluegrass turf gave best
response for polymer coated urea XCU (43-0-0) as compared to Polyon (44.5-0-0) on
the basis of mean visual response likes colour, quality and uniformity. But, XCU at
the 1-lb rate showed significantly better response than the XCU @ 2 lb N 1,000 ft-2.
Hatfield and Parkin (2014) revealed that use of enhanced efficiency fertilizers
(EEFs) in maize resulted in an increased greenness in canopy, delayed senescence of
the plant, increased chlorophyll index or the plant senescence index and the duration
of green leaf area during the grain-filling stage.
Field studies were conducted by Qin et al. (2014) from 2009 to 2012 near
Lethbridge, AB, Canada, to determine how upper limits of seed safety using seed-
placed environmentally smart nitrogen fertilizer (ESN) in cereals and canola change
with increased N rates and alterations to the coating integrity of ESN. The findings
from this study indicate that safe (no yield reduction) seed-placed rates could be
increased to 60 kg N ha-1 for canola and up to 90 kg N ha-1 for spring cereals if ESN is
handled properly to maintain coating integrity within N release range of 20 to 40%,
but safe limit for seed-placed urea was generally 30 kg N ha-1.
A 3-yr study was conducted on a sandy-loam soil in Quebec, Canada, to
examine the effect of PCU application rate (0, 60, 120, 200, and 280 kg N ha–1) on
petiole NO3–N concentrations, chlorophyll meter readings (SPAD readings), soil
mineral N content, and total tuber yield (Cambouris et al., 2014). The NO3AEM values
(NO3 adsorbed by anion exchange membranes), petiole NO3–N concentrations, SPAD
Review of Literature
~ 10 ~
readings, soil mineral N content, and total tuber yield increased with PCU application
rate. The NO3AEM values fluctuated during the growing season due to plant N uptake
and variations in soil moisture content.
From the research studies carried out in a greenhouse by Pinpeangchan and
Wanapu (2015) it was found that encapsulated urea fertilizers (EUFs) increase fresh
weight, root fresh weight, stem dry weight and root dry weight of kale plant. Stem
length showed a significant difference at P value ≤ 0.05 highest in urea, EUF-2
(PVA/PVP=1:0), EUF-3 (PVA/PVP=1: 0.25) and EUF-6 (PVA/PVP=1:2). Plants
with control, osmocote, polyvinyl alcohols (PVA) and poly vinyl pyrrolidone (PVA)
resulted in lowest stem and root dry weight. Application of coated urea slightly
increased leaf area, while control, osmocote, PVA, and PVP had smaller leaf area.
2.3 Effect of polymer coated urea (PCU) on Yield attributes
Trials with maize and sugarcane (Bishop, 1993) showed that prills of urea or
LAN (limestone ammonium Nitrate) coated with 0.5% of a styrene-octyl acrylic
polymer initiated substantially more plant leaf N and more corn grain in recently tilled
soils and higher estimated recoverable sugar (ers) % cane and fibre % cane values in
ratoon crops than equivalent uncoated commercial. Coated LAN (limestone
ammonium Nitrate) gave more cane and more ers ha-1 than commercial LAN. Of the
two coatings, one of 0.5% polymer tested with ratoon cane encouraged both
vegetative growth (tons cane ha-1) and earlier maturity (higher ers % and fibre %
cane) with limestone ammonium Nitrate at both 80 and 120 kg N ha-1, while at the
0.01% polymer level only increase vegetative growth at 80 kg N ha-1.
Singh et al. (1995) reported that grain yield of lowland rice from a single
application of polymer coated urea (PCU) was equivalent to or better than 3-4 time
split application of urea. Fertilizer recovery with PCU was 70-75% compared to 50%
with prilled urea.
Bishop (1998) stated that maize grain yields had a positive correlation with
total rainfall and a negative correlation with leaf Ca (r = -0.5723 NS) and Mg values
(r = -0.5614 NS) with both commercial and coated urea. The more restrained rate of N
release from the fertilizers coated with 0.5% polymer produced hardier, less
Review of Literature
~ 11 ~
vegetative crops, lower stover to grain in maize and sugarcane crops with lower ratios
of tons cane to estimated recoverable sugar (ers) % cane than those produced by
commercial N. The crop with polymer coated N mature earlier than commercial N.
The result of an experiment conducted at 2 sites on imperfectly drained soil in
2002 by Schwab and co-workers indicated that with only 60 lbs N/a applied in wheat,
the split product (1/3 urea+2/3 PCU) application produced significantly higher grain
yield than all the other post-plant applications except for urea applied in March. At
Princeton site, the yield of the urea/PCU mix was over 8 bu/a higher than the
traditional split application of urea.
Carreres et al. (2003) concluded that he highest grain yield (9.37 t ha-1) was
obtained with polymer coated urea (PCU 40% N), and then the ranked order was
ammonium sulphate nitrate (ASN) plus dimethyl pyrazole phosphate
(DMPP)> isobutylidenediurea (IBDU)> ASN plus dicyandiamide (DCD)> PCU (32%
N)> sulphur coated urea (MSCU). PCU (40% N) application resulted in a higher
number of spikelets per panicle than any other N source application irrespective of
delay in flooding after N application.
Zvomuya et al. (2003) stated that under leaching conditions (≥ 25 mm
drainage water in at least one 24-h period) and in excessive irrigation, PCU at 280 kg
N ha-1 in ‘Russet Burbank’ potato improved total and marketable tuber yields by 12
to 19% compared with applications of urea in 3 splits.
According to the findings of an experiment conducted at BHU farm by Singh
et al. (2004) it was concluded that co-situs application of iron 75% through pyrite plus
25% through polyolefin resin coated slow release Fe (PRCSRFe) fertilizer sustained
crop productivity in calcareous soil. The highest mean grain and straw yield of 41.46
and 93.195 g hill-1, panicle weight, grain panicle-1, test weight were obtained in paddy
with the application NPK + 75% pyrite + 25% PRCSRFe which was at par with NPK
+ 50% pyrite + 50% PRCSRFe and NPK + 100% PRCSRFe.
Bundy and Andraski (2007) revealed that a single preplant application of
environmentally smart nitrogen fertilizer (ESN) was more effective than sidedress or
split applications of ammonium sulphate (AS) or urea in terms of yield and fertilizer
Review of Literature
~ 12 ~
N recovery in both high and normal rainfall years. 4 years of data showed that ESN
was much better as a preplant treatment in wet years than conventional fertilizers in
corn.
Pack et al. (2006) compared Controlled-release fertilizers (CRF) with
ammonium nitrate (AN) in potato (Solanum tuberosum L.) at the University of
Florida farm in Hastings, FL. Treatments were no nitrogen (No-N), AN, and nine
CRFs at 146 and 225kg N ha−1. CRF (225 and 146 kg N ha−1) resulted in highest total
and marketable yields at 33.7 MT ha−1 and 29.4 MT ha−1 respectively.
Worthigton et al. (2007) observed thatplants in controlled release fertilizer
(CRF) treatment produced 12% higher marketable tuber yield with 13% less N
application compared to ammonium nitrate (AN) treatment.
Golden et al. (2009) reported that pre-plant incorporated polymer coated urea
increased rice grain yield and N uptake in the direct seeded, delayed flood method
over urea applied at the five-leaf stage.
Noellsch et al. (2009) found that in maize, pre-plant incorporated polymer
coated urea increased N fertilizer recovery efficiency and grain yield over control in
the clay pan landscapes.
Taysom et al. (2009) reported that both environmentally smart nitrogen
fertilizer (ESN) and urea performed significantly better than the untreated check.
Polymer coated urea (PCU) [67 % of RDF] at emergence in potato produced
significantly highest total tuber yield, US No.1, marketable (including both US No.1&
2) and crop value (gross & net crop value) among all treatment with different
placement method and differs N rates (33%, 67%, 100% and 130% of RDF).
Yield results from three research sites indicated that 38% N PCU fertilizer
produced yields that were comparable, albeit slightly lower (when all three sites are
considered), to urea applied preflood and shows promise as a fertilizer that could
potentially be used in the direct-seeded, delayed-flood rice production system (Slaton
et al., 2009).
Review of Literature
~ 13 ~
The result of a trial conducted on potato in 2010 by Rosen and co-workers
showed that the potato tuber yield from dealer grade ESN-C (Environmentally Smart
Nitrogen fertilizer) was numerically higher than that of air boom ESN sample (ESN-
A) by nearly 45 cwt/a (8.5%), but these differences were not statistically significant.
Emergence applied ESN-C also produced significantly higher marketable yields than
the emergence ESN-C/urea blend and higher % of larger tuber (≥10 oz) than control
treatment.
Jun-gang et al. (2010) conducted an experiment in China on summer maize
and observed that the maize grain yields from N fertilized treatments were
significantly increased, which were 9.61 to 10.4 t/ha higher than the controlled
treatment without fertilized (8.71 t/ha). The yield from the PCFN2 treatment (120 kg
ha-1 N) was similar to that of conventional fertilizer treatment (180 kg ha-1 N).
Patil et al. (2010) found that for both the growing seasons in 2006-07, all the
polymer coated urea (PCU) treatments showed better performance than the treatment
with uncoated fertilizer alone (N80C0). Total number of grains per panicle as well as
grain yield in paddy was significantly higher in PCU treatments (N56C39 and N40C20)
than conventional urea treatment (N80C0).
Yi et al. (2011) studied the effects of different dosages of coated controlled
release urea (PCU-60, 60 days release duration) combined with conventional urea (U)
on winter wheat growth and observed that at the same N dosage, all the test indices of
PU4 (40% PCU-60+60% U) were significantly higher. The grain yield, N recovery
rate, total N accumulation amount, total tiller number and aboveground biomass at
ripening stage, and economic benefit increased by 5.6%, 14.6%, 7.2%, 2.6%, 7.5%,
and 984.3 yuan ha-1 respectively over check.
Gagnon et al. (2012) conducted an experiment during 2008-2010 and found
that fertilizer treatments increased corn yield in all 3 yrs. of the study, but the
magnitude of the response varied with years. In the wet years (2008 & 2009) polymer
coated urea (PCU), urea ammonium nitrate 32% (UAN) and nitrification inhibitor
urea (NIU) significantly increased yields by 1.6, 1.4 and 0.6 Mg ha-1 over urea
respectively. Grain N concentration showed linear response with increasing rates of
Review of Literature
~ 14 ~
urea and PCU in 2010 and quadratic in 2008 and 2009.In 2008, only polymer coated
urea and urea ammonium nitrate treatments (UAN) @ 150 kg N ha-1 gave higher
grain N than the control.
Ma et al. (2012) studied the effects of sulfur and polymer-coated controlled
release urea fertilizers on wheat yield and its quality. It was found that both sulfur-
and polymer-coated controlled release urea fertilizers raised the grain yield by 10.4%-
16.5%, and the grain protein and starch contents by 5.8%-18.9% and 0.3%-1.4% over
traditional urea fertilizers, respectively.
Nash et al. (2012) stated that fertilized treatments had 550 to 2080 kg ha−1
greater winter wheat grain yield than the uncoated controls regardless of the N
application date in double-cropped winter wheat with soybean. Wheat yields were
generally greater when N was applied at 112 kg N ha−1 compared to 84 kg N ha−1,
except for April applications of N fertilizer sources. The average yield with an
application of 100% NCU (non coated urea) and ammonium nitrate (AN) at 112 kg
ha−1 were similar to 75% PCU + 25% NCU at 84 kg ha−1 .
Nash et al. (2013) conducted a field trail in 2008- 2010 (high rainfall years)
near Novelty and observed that Fall and preplant strip-till placement of polymer
coated urea increased grain yield by 1.2 Mg/ha compared to no coated urea in corn.
Strip-till placement of polymer coated urea synergistically increased yield over un-
coated urea and broadcast applications of PCU or uncoated urea due to increased
stands and possibly due to better plant utilization of the banded N fertilizer.
A 4-yr (2010-13) research was conducted by Nashand his co-workers to
determine yield response of corn to polymer-coated urea (PCU) with subsurface
drainage [free drainage (FD) or managed drainage (MD)] and non-coated urea (NCU)
without drainage (ND) in a claypan soil. Averaged over 2010 to 2013, PCU increased
corn grain yield by 20% compared to NCU, which indicated that PCU mitigated the
high N loss potential in a wet soil environment.
Field experiments were conducted by Farmaha and Sims (2013) during 6 site-
years in Minnesota from 2007 to 2009 to examine effects of a polymer-coated urea
[PCU, environmentally smart nitrogen (ESN)] and non-coated urea on grain yields
Review of Literature
~ 15 ~
and protein concentrations of two HRSW cultivars, Alsen and Knudson. The wheat
cultivar Knudson produced greater grain yield. Because of delayed N release from
PCU, greater protein concentration (at physiological maturity, Zadoks scale 92) and
whole tissue N concentration (at the soft dough growth stage, Zadoks scale 85) were
observed with PCU in environments that experienced cool and dry spell in the early
growing season. At the same rates of N, PCU increased protein concentration as
compared to urea, but required higher N rate to maximize grain yield.
Nelson et al. (2014) found that wheat yields were generally greater when
polymer coated urea (PCU) was fall-applied compared to split-applied. In poorly
drained soils wheat grain yield was highest with PCU followed by ammonium nitrate
(AN), urea plus N-(n-butyl) thiophosphoric triamide (U + NBPT) than urea. Polymer-
coated urea is a viable option for fall application to wheat in poorly drained soils.
2.4 Effect of polymer coated urea (PCU) on nutrient uptake
An experimental study was initiated by Schwab and his co-workers in 2002 on
imperfectly drained soils at Lexington and Princeton to compare application timing of
PCU (ESN) and urea for wheat production. N uptake and dry matter accumulation at
flowering stage and N removal by grain were higher in polymer coated urea(PCU)
than urea at 60 lbs N/ac applied before planting. Very low nitrogen use efficiency
(NUE) was observed for urea and ammonium nitrate treatments with (25%) use
efficiency comparative to the fall PCU (> 50%). The average NUE for the pre-plant
treatments was 37% while the post-plant treatment was 56%. The maximum NUE
was measured when a mix of 1/3 urea and 2/3 PCU was applied in February.
Zvomuya et al.(2003) conducted a trial on potato in coarse-textured soil and
fertilizer N recovery efficiency was estimated by the difference and 15N isotope
methods at the 280 kg N ha-1 rate. N recovery efficiency was higher with PCU (mean
50%) than urea (mean 43%).
A trial conducted in the rice field of Valencia (Spain) by Carreres
(2003)showed that polymer coated urea (32% and 40% N) and isobutylidenediurea
(IBDU) application shortly before flooding improved total N uptake and recovery
Review of Literature
~ 16 ~
efficiency compared to the conventional fertilizer application, with or without
nitrification inhibitors.
Singh et al. (2004) stated that the different iron sources had a marked effect on
nitrogen, phosphorus, potassium, and iron accumulation by paddy grain, straw as well
as total accumulation by the above ground biological produce and the highest values
were obtained with the application of NPK + 75% pyrite + 25% PRCSRFe.
Tubers from plants under all fertilized treatments removed significantly more
N from the field than tubers from plants under the No-N treatment (Pack et al., 2007).
Plants under TRT-10 (146 kg ha−1 N) and TRT-16 (146 kg ha−1 N) had the highest
nitrogen-removal efficiency (NRE) which were significantly higher than potatoes
under TRT-3 (AN, 225 kg ha−1 N; 24.12%).
Kanno (2008) observed a non-significant difference between the polyolefin
coated urea (POCU-70 and POCU-30+ S60) treatment in total N uptake (TNU) in
corn at all the sampling stages, although the total N uptake by corn plant in 1994 was
significantly higher than 1995. The yearly means of fertilizer-derived N uptake
(FDNU) in the urea, POCU-70 and POCU-30 + S-60 treatments were 77.0, 77.4 and
93.0 kg N ha-1at the harvest respectively.
Junejo et al. (2010) observed that the concentration of Cu and Zn removed by
maize plant was significantly higher in coated urea than uncoated urea treatment.
Total N uptake in plants was found to be in the order of micronutrient coated urea >
gelatin + Cu coated urea > Palm stearin + Cu coated urea > Cu coated urea > Agar +
Cu coated urea > uncoated urea, which was 762, 676, 523, 491, 324 mg pot-1,
respectively.
Patil et al. (2010) reported that the small amount of uncoated urea (as low as
12 kg N ha-1) in coated fertilizer mixture was sufficient to fulfil the initial N
requirement of paddy. After the initial growth stage, plant N concentration (PNC) was
more influenced by coated urea as in 2006, N56C39 and N40C28 at 40 & 47th DAT had
significantly greater PNC than N80C0 and N40C20 treatments.
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~ 17 ~
Rosen and co-workers in an experiment on potato in 2010 revealed that mean
concentrations of NO3- in the petiole samples were numerically lowest for the control
on all dates except Aug 12 and significantly lower than those of all treatments on June
7 and June 22.
Sahota et al. (2010) revealed that in winter wheataverage N removal by grain
was 120 kg N/ha which was 7 kg/ha higher with environmentally smart nitrogen
(ESN) than urea. Total N removal by grains + straw was ~180 kg/ha (14 kg/ha higher
with ESN than urea). But in spring wheat there was no significant effect of
environmentally smart nitrogen (ESN) on grain yield, straw yield, plant N content and
grain protein content.
Fageria (2011) reported that NUE was significantly higher at the polymer
coated urea (PCU) as compared to conventional urea. The increase in nitrogen use
efficiency (NUE) by polymer coated urea was about 25% in relation to conventional
urea. The higher nitrogen use efficiency of PCU may be related to the slow release of
N in the soil-plant system according to plant demand and consequently higher
utilization.
Gagnon et al. (2011) reported that in corn, increasing urea rate linearly
decreased apparent N recovery from 50 to 39%. However, this relationship was not
statistically significant with polymer coated urea (PCU) rate. The PCU treatment at
150 kg N ha-1 had higher apparent N recovery than urea.
Ma et al. (2012) reported that controlled release urea fertilizers could sustain
the top soil inorganic N supply to meet the N requirement of the wheat, especially
during its late growth stage. The N use efficiency was enhanced by 58.2% to 101.2%.
Polymer-coated urea produced better wheat yield and higher fertilizer N use
efficiency, compared with sulfur-coated controlled release urea.
Zebarth et al. (2012) stated that plant N uptake was greater under polymer
coated urea (PCU) than under the conventional and split N application in potato,
althoughthese differences were not statistically significant. Petiole NO3-
concentrations and the NNI (Nitrogen nutrition index) were greater for the PCU than
the other two fertilize treatments.
Review of Literature
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2.5 Residual effect of polymer coated urea (PCU)
Junejo et al. (2010) conducted an experiment to determine the residual effect
of coated and uncoated urea on corn biomass. The highest dry matter yield was
obtained from Agar + Cu coated urea (26.5 g pot-1) and this was followed by
micronutrient coated urea, Cu coated urea, gelatin + Cu coated urea, Palm stearin +
Cu coated urea in descending order, while the lowest from uncoated urea (12.5 g
pot-1).
Sahota et al. (2010) studied the residual effectof coated urea on the timothy
crop at Thunder Bay and found that environmentally smart nitrogen (ESN) @ 70 kg
N/ha produced the highest dry matter yield, which was 650 kg/ha higher than urea at
the same rate of N.
The experiment conducted at glass house on corn by Junejo et al. (2010)
revealed higher beneficial residual effects of coated urea on nutrient uptake by plant
as compared to urea alone. Nutrients (Cu & Zn) uptakes were found to be less in
coated urea than urea alone, due to the dilution effect as a result of increase in dry
matter yield. The N uptake of plant was found to be in the order of Cu coated urea >
micronutrient coated urea > gelatin + Cu coated urea > Agar + Cu coated urea > Palm
stearin + Cu coated urea > uncoated urea respectively.
Jun-gang et al. (2010) found that the residual nitrogen was minimum in the
60-90 and 90 -120 cm layer under the conventional fertilizer (180 kg ha-1 N), while it
was significantly higher in polymer coated N fertilizer (PCFN1) with co-situs
placement than that check (no fertilizer) after harvesting of summer maize.
The result of a trial conducted on potato in 2010 by Rosen and co-workers
showed non-significant differences among individual treatments with respect to post-
harvest residual soil N. Mean soil N levels were equivalent to 0.8 to 4.8 lb/acre N for
ammonium and 22.2 and 27.9 lb/acre N for nitrate.
Gagnon et al. (2011) found significant interaction between treatments × year
for the residual soil NO3- after corn harvest in 0 to 15 cm upper layer. Concentration
Review of Literature
~ 19 ~
of soil NO3- was increased by the PCU in all the years, (2 kg ha-1 in 2008 to 9 kg ha-1
in 2009 at 150 kg N ha-1 rate).
Fageria (2011) found that Ca saturation, Mg saturation, exchangeable soil Ca
& Mg, base saturation and effective cation exchange capacity were significantly
higher in the treatment which received polymer coated urea as compared to
conventional urea. This may be related to controlled and slowly available Ca & Mg
due to the application of PCU for N.
2.6 Effect of polymer coated urea (PCU) on environment
Zvomuya et al. (2003) found that a single application of PCU improved
recovery of N and reduced NO3 leaching compared to three application of urea. NO3-
leaching during the growing season was lower with polymer coated urea (34 to 49%)
than three split applications of urea in potato field. Under standard irrigation in the
third year, leaching from five split applications of urea (280 kg N ha-1) was 38%
higher than PCU. Similar results were reported by Waddell et al. (2000), comparing
sulphur coated urea SCU with urea.
A trial at the University of Florida research farm in 2004 revealed that
controlled release fertilizer (CRF) rates can be reduced up to 50% compared to
soluble nitrogen sources (a reduction of 100 lb N/acre) without reducing potato tuber
yield and quality (Pack et al., 2006). Nitrate movement data indicated that nitrogen
leaching below the root zone can be reduced by 60-80% compared to conventional
fertilizers
Pack et al. (2007) observed significantly higher concentrations of NO3--N in
the soil solution from suction lysimeters with ammonium nitrate (AN) @ 146 kg
ha−1 N and 225 kg ha-1was 127 mg L−1 NO3--N and 172 mg L−1 NO3
- -N respectively
than with any controlled release fertilizer (CRF) at 39 DAP. Thus it clearly indicated
that any CRF is better than ammonium nitrate in reducing NO3--N in the soil solution.
Nelson et al. (2009) was conducted a trial to evaluate NO3-–N concentrations
in soil water samples and to determine differences in corn yields and N utilization in
non-coated urea (NCU) and polymer coated urea (PCU) treated plots under different
Review of Literature
~ 20 ~
water management systems. Water samples from suction lysimeters at a 45 cm depth
in soil treated with PCU had 51 to 63% lower NO3-–N concentration than NCU at 59
days after application (DAA), while NCU had 85 to 92% lower N concentration than
PCU 153 DAA.
Wilson and co-workers (2010) made a comparative study on N leaching with
polymer coated urea (PCU) and urea found that PCU significantly reduced leaching
and improved N recovery over soluble N applied in two splits and resulted in similar
N recovery and nitrate leaching as soluble N applied in six splits. Nitrate leaching
with (Environmentally Smart Nitrogen) ESN (21.3 kg NO3--N ha-1 averaged over N
rates) was significantly lower than with split-applied soluble N (26.9 kg NO3--N ha-1,
but significantly in Apparent N recovery i.e. 65% (averaged over four rates) with
PCU than 55% with split-applied soluble N at equivalent rates (p = 0.059).
The findings of a field trail on turf grass by LeMonte et al. (2011) reported
that with providing an adequate N supply to Kentucky bluegrass/perennial ryegrass,
polymer coated urea(PCU) application resulted in decreased NH3 volatilization by
41–49% compared to urea application. Using uncoated urea as an N fertilizer resulted
in 127 – 476% more measured N2O impact on the environment, whereas PCU was
only 25 – 52% higher (not significant) than background emission levels.
A field study in Utah on polymer coated urea in Kentucky bluegrass and
perennial ryegrass showed reduction in NH3 volatilization by 41-50% compared to
untreated urea (Story et al., 2011). Similar results were observed in a study in Georgia
(Connell et al., 2011).
Of the total global anthropogenic NH3 emission of 43 Tg N yr−1, 12.6 Tg
N yr−1 is from cropland (not including animals on cropland). It was observed that
Polyon, which is a slow release fertilizer, decreased N2O emission by 96% besides
4% CH4 emissions (Linquist et al., 2012).
A 2-year field study was carried out by Yang and co-workers (2013) to
investigate the effect of controlled release nitrogen fertilizer management on nitrogen
loss from paddy field under water saving irrigation and found nitrogen export from
paddy fields to be reduced by 36.3 kg N ha-1 in comparison to farmer practice.
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Halvorson et al. (2014) observed that environmentally smart nitrogen (ESN)
reduced N2O emissions by 42% compared with urea and 14% compared with urea
ammonium nitrate (UAN) in no-till (NT) and strip-till (ST) with no effect in a
conventional till (CT).
Gao et al. (2014) examined the effect of placement and enhanced efficiency
fertilizers on N2O emissions from spring wheat (Triticum aestivum L.) at two
locations in Manitoba. Total N2O emission from midrow-banded environmentally
smart nitrogen (ESNM) and midrow-banded SuperU (SuperUM) was similar, being 19
and 51% smaller than for midrow-banded urea placement between every other set of
rows (UreaM) at Carman and Oak Bluff, respectively (P< 0.001). The average daily
N2O emission rate for both sites was 30.2 a, 24.7 ab, 21.0 bc, 15.8 cd, 14.6 d and 8.0 e
g N ha–1 day–1 from broadcast-incorporated urea (UreaI), subsurface side-banded urea
(UreaS; each row side-banded), UreaM, SuperUM, ESNM, and Control respectively
with significant (P< 0.10) differences.
Materials and Methods
~ 22 ~
Chapter- III
Materials and Methods
The present investigation entitled “Effect of polymer coated urea on the
growth and yield of rice[Oryza sativa (L.)]” was conducted during the kharif
seasons of 2014 at the Agriculture Research Farm, Institute of Agriculture Sciences,
Banaras Hindu University, Varanasi. The details of the methods employed and
materials used in the present experiment have been described here. The climate, soil
and crop conditions, cropping history of the experimental area have also been
presented in this chapter.
3.1 Experimental site
The Agricultural Research Farm is situated in the south-eastern part of
Varanasi city at a distance of about 10 km from Varanasi cant railway station.
Geographically, the experimental site falls under sub-tropical zone of Indo-Gangatic
plains and lies on the left bank of river Ganga. It is located on 2518 N latitude,
8303 E longitude and at an altitude of 77 meters above mean sea level. The
experimental plot was homogenous in fertility with assured irrigation and other
required facilities.
3.2 Climatic condition of Varanasi
The weather of Varanasi is categorized under moisture deficit index of 20-40
percent and falls in the belt of semi-arid to sub humid climate having hot summer and
cold winter. The normal period for the onset of monsoon in this region is the third
week of June and it lasts upto the end of September and sometimes up to the first
week of October. A light shower is often experienced in January and February. Month
of March to May are generally dry. The distribution of rainfall is 88% from June to
September, 5.7% from October to December, 3.3% from January to February and 3%
from March to May. The average annual precipitation (P) of Varanasi is 1100 mm and
annual potential evapo-transpiration (PET) is about 1525 mm. The annual moisture
deficit in this region is about 425 mm. The differences between total rain fall received
(about 875 mm) and evaporation losses (about 665 mm) is always positive (about 210
mm) during rainy season (from July-October). However, in the subsequent months
Materials and Methods
~ 23 ~
from November to June, the differences are always negative. Generally maximum and
minimum temperature ranges between 17.90C to 36.30C and from 9.80 to 28.30C,
respectively. The temperature begins to rise from the middle of February and reaches
its maximum in middle of June. The coldest period of the year is between last week of
December to first week of January. The mean relative humidity is 70 per cent, which
rises up to 94.0 per cent during January and fall down to 42 percent during the end of
April to early June. The detail of meteorological data for the experimental period
(2013-2014) is presented in Table 3.1.
Table 3.1: Weekly meteorological data of Varanasi during experiment period
(June, 2014 to October, 2014)
Week
No.
Month &
Date
Rainfall
(mm)
Temperature
(0C)
R.H.(%) Wind
Speed
km/hr
Sunshine
(hrs.)
Evaporation
(mm)
Max. Min. Morn Even.
23 June 04-10 0.0 43.4 28.3 62 27 3.9 9.5 7.0
24 11-17 5.4 37.6 28.5 64 39 6.6 6.6 7.7
25 18-24 42.9 37.7 27.7 74 44 6.1 3.8 5.1
26 25-01 12.8 38.8 28.5 71 42 3.9 5.2 6.9
27 July 02-08 65.9 33.9 26.6 83 71 4.0 2.2 4.2
28 09-15 0.0 36.7 28.7 79 63 4.8 7.9 5.4
29 16-22 261.5 32.8 26.8 92 84 6.1 1.4 2.8
30 23-29 4.6 33.3 26.6 82 65 2.4 4.8 3.3
31 30-05 46.0 32.8 27.7 87 74 5.4 5.7 4.4
32 Aug 06-12 142.7 32.9 26.4 87 74 5.1 4.1 3.3
33 13-19 42.4 23.6 27.6 86 79 5.4 2.4 2.8
34 20-26 14.0 35.1 27.5 77 60 4.0 6.7 4.4
35 27-02 6.5 33.0 27.1 84 71 7.2 5.3 4.6
36 Sep 03-09 34.9 32.7 26.4 85 69 5.0 6.0 3.0
37 10-16 11.0 31.9 25.8 91 80 1.8 4.0 3.1
38 17-23 13.7 33.3 26.0 87 72 1.6 5.2 3.4
39 24-30 2.1 33.4 24.3 85 56 3.6 9.3 4.1
40 Oct 01-07 0.0 32.2 24.2 79 64 1.2 7.2 3.1
Materials and Methods
~ 24 ~
Fig. 3.1: Standard weekwise Meteorological Observations recorded at the Meteorological Observatory of the Department of Agronomy,
I.Ag. Sc., BHU during the period of experimentation (June, 2014- October, 2014)
0
1
2
3
4
5
6
7
8
9
10
0
50
100
150
200
250
300
23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Standard week
win
d s
pe
ed
, s
un
sh
ine
, e
va
po
rati
on
Rain
fall
, T
em
pe
ratu
re, R
H
Rainfall (mm) Max Temp. (0C) Min Temp. (0C) Morn. RH (%)
Even. RH(%) wind speed (km hr-1) sunshine (hrs) evaporation (mm)
Materials and Methods
~ 25 ~
The details of different weather parameters during the period of experiment are given
below:
3.2.1 Temperature (0C)
The weekly mean minimum and maximum temperature during the
experimentation ranged from 24.20C to 28.70C and 23.60C to 43.40C, respectively.
The maximum temperature 43.40C was recorded in 23rd standard week in the month
of June 2014 whereas; the lowest minimum temperature remained 24.2C in the 40th
standard week of October.
3.2.2 Rainfall (mm)
The cumulative rainfall during the period of investigation in the cropping year
2014 (20th June-1st October) was 706.4 mm.The pattern of rainfall distribution was
erratic during the experimental period with the highest rainfall (261.5 mm) being
observed during 29th week of the year in July.
3.2.3 Sun-shine duration (hrs)
The average duration of bright sunshine was 5.41 hours. The maximum and
minimum weekly bright sunshine duration ranged between 9.5 to 1.4 hours,
respectively during the period of investigation.
3.2.4 Relative Humidity (%)
The weekly morning relative humidity ranged between 62% (04-10 June) to
92 % (16-22 July) and evening relative humidity varied from 27% (04-10 June) to
84% (16-22 July) during the period of investigation.
3.2.5 Evaporation (mm)
The evaporation data obtained from weather bureau class A Pan Evaporimeter
revealed that the average evaporation during the crop period varied from 2.8 to 7.0
mm day-1.
Materials and Methods
~ 26 ~
3.3 Soil
Varanasi lies almost in the middle of the Indo-Gangetic alluvial plainsand the
soil is typically Gangetic alluvium (order-inceptisol). These soils are deep, low in
available nitrogen and medium in available phosphorus and potassium. The soil of the
experimental field was sandy clay loam in texture with its natural drainage facilities.
Before the start of experiment, composite soil samples were collected with the help of
auger and core sampler and the soil samples thus obtained were subjected to various
electro-chemical and biological analyses which is as follows.
Table 3.2: Mechanical and chemical soil analysis of the experimental plot
Particulars Before
sowing
After
harvesting
Method employed
(A) Mechanical analysis
Hydrometer method
(Bouyoucos,1962)
Soil separates
1. Coarse sand (%) 8.28 8.27
2. Fine sand (%) 52.4 52.4
3. Silt (%) 19.5 19.4
4. Clay (%) 18.5 18.5
5. Texture class (%) Sandy clay
loam
Sandy clay
loam
(B) Physical analysis
Bulk density (gcc-1) 1.35 1.35
(C) Chemical analysis
Electrical conductivity
(dsm-1 ) at 250C
0.29 0.29 Conductivity bridge
(Jackson,1973)
Soil pH (1:2:5 soil and water
suspension)
7.4 7.5 Glass electrode digital pH
meter (Jackson,1973)
Organic carbon (%) 0.38 0.38 Walkley and Black’s Method
(Jackson,1973)
Available Nitrogen (kg ha-1) 179 188 Alkaline permanganate
(Subbiah and Asija,1956)
Available P2O5 (kg ha-1) 18.0 18.4 0.5N NaHCO3 extractable
(Olsen et al.,1995)
Available K2O (kg ha-1) 199.6 199.0 Ammonium acetate
extractable flame photometer
(Jackson,1973)
3.4 Experimental design and layout
The experiment consisting of 5 treatments was laid out in a Randomized
Complete Block Design with four replications and conducted in open bottom circular
Materials and Methods
~ 27 ~
cemented pots having diameter of 60 cm. The height of each pot was 25-30 cm and these
were buried half in field at a depth of 12-15 cm.
3.3 (a) Treatment details:
U0 - Urea super granules
U1 - Polymer coated urea (single coating)
U2 - Polymer coated urea (double coating)
U3 - Neem coated urea
U4 - Sulphur coated urea
Table 3.3 (b): Details of layout.
Site : B.H.U., Varanasi, UP
Design : Randomized Complete Block Design
Treatment : 5
Replication : 4
Pot size : 1926 cm2
..……………………….FARM SUB ROAD ……………………….
R-I R-II R-III R-IV
U2 U4 U2 U1
U0 U1 U0 U3
U4 U3 U4 U0
U1 U0 U1 U2
U3 U2 U3 U4
Fig. 3.2: Layout plan of pot experiment
N
S
W E
Materials and Methods
~ 28 ~
3.5 Selection of experimental materials
3.5.1 Selection of crop variety
NDR-97 selected for the study is an early maturing varietyof rice which matures in
about 90-100 days. Plants are of medium statured with dark green foliage and high
yield potential (3.0-4.0 t ha-1).
Important attributes:
Parentage : Nagina-22 ×Ratna
Released in : 1992
Breeding : Hybridization & Pedigree method selection
Height : 80-85 cm
Maturity : 90-100 Days
Tillering : 8-15 tillers
Lodging : Lodging resistant
Flowering : Flowering in 70 days
Panicle : Medium (18-25 cm, drupes) due to erect study plant
stature
Grain type : Long -slender
Yield : 30-40 q/ha
Resistant /Tolerant : Brown spot, blast and seed rot
3.5.2 Source of nutrients
In rice crop, a uniform recommended dose of 102 kg N, 60 kg P2O5 and 60 kg
K2O ha-1 was applied to all the plots. Phosphorous and potassium were applied
through Diammonium Phosphate (2.5g) and Muriate of Potash (2g) as basal
application at transplanting respectively. The coated urea fertilizers like polymer
coated urea (PCU), neem coated urea (NCU), sulphur coated urea (SCU) and urea
super granules (USG) were applied a week after transplanting to supply nitrogen
Materials and Methods
~ 29 ~
needed by plant during its entire growth period. 2g of these coated urea fertilizers
were deep-placed at 7.5 cm at the center of four hills.
3.5.2.1.1 Urea super granules (USG)
Urea super granules are large urea granules of about ≥1 gram developed for the
purpose of enhancing NUE. They are primarily intended for wetland transplanted rice
grown on puddled soil. Deep placement of USGs resulted in higher grain and straw
yield as well as better nutrient uptake in lowland paddy.
3.5.2.2 Sulphur coated urea (SCU)
Sulphur-coated urea (SCU) was developed at the TVA in 1961. It is prepared
by spraying molten sulphur over granular urea to yield a product containing
between31 to 38% N. A wax sealant is then sprayed to seal cracks in the coating
andto reduce leakage and microbial degradation of the S coating (Shaviv, 2000).
Release of nutrients is controlled by physical breakdown of coatings, microbial
decomposition of the sulphur and hydrolytic cleavage of S-S linkages. Jarrell and
Boersma (1980) suggested an Arrhenius-type expression for the model pertaining to
the effect of temperature on nitrogen release from sulphur-coated urea (SCU).
3.5.2.3 Neem coated urea (NCU)
Techniques for preparing neem coated urea were developed at IARI, New
Delhi. One technique is coating urea with neem cake byusing a coal-tar kerosene
mixture and by neem oil micro-emulsion (Suri et al., 2000). The oil obtained from its
fruits and the press cake from the production of neem oil was used for the production
of neem coated urea (NCU). This has been adapted by several companies in India and
is sold as neem coated urea. Prasad et al. (2002) reported the superiority of NCU over
conventional urea for rice. Field trials by National Fertilizers Limited showed a yield
increase of 10.4 % in Haryana, 9.6 % in UP and 14 % in Punjab over prilled urea.
Materials and Methods
~ 30 ~
3.5.2.3 Polymer coated urea (PCU)
Polymer coated urea is one of the controlled release fertilizers which is a new
approach in agriculture for enhancing nitrogen use efficiency and sustaining yield.
Polymer coated urea are prepared by coating urea granules with polyethylene,
polyester and other biodegradable polymers likes polylactic acid (PLA),
polyhydroxyalkanoate (PHA), poly vinyl alchohol and polycaprolactone. Polylactic
acid (PLA) is at present one of the most promising biodegradable polymers
(biopolymers) and can be processed with a large number of techniques and is
commercially available (large-scale production) in a wide range of grades (Avérous,
2008).
Polylactic acid (PLA) is a polymer of lactic acid with higher molecular
weight. PLA belongs to the family of aliphatic polyesters commonly made from
hydroxy acids that includes, for example, polyglycolic acid (PGA). It is one of the
polymer in which the stereo-chemical structure can easily be modified by
polymerizing a controlled mixture ofl and d isomers to yield high molecular weight
and amorphous or semi-crystalline polymers. Properties can be both modified through
the variation of isomers (l/d ratio) and the homo and (d, l) copolymers relative
contents. Moreover, PLA can be tailored by formulation involving addition of
plasticizers, other biopolymers, fillers, etc. (Avérous, 2008).
3.5.2.3.1 Preparation of Polylactic acid polymer coated urea fertilizers
Urea granules are coated by solution method, reactive layer coating technique
and thermoplastic resin coating. PLA coated urea are prepared by solution method.
For preparing PLA coated urea, a solution of poly lactic acid was prepared and urea
granules were dipped in solution as it completely adheres round the granules/particles
and then it is dried.
3.6 Cultivation practices
Detail of the operations carried out to get the field prepared for rice during the
entire period of investigation are described below and calendar of field operations are
given in Table 3.4.
Materials and Methods
~ 31 ~
Table 3.4: Schedule of field operations carried out during experiment
S. No. Operations Date
1. Nursery raising
a) Pre sowing irrigation 20-06-2014
b) Ploughing 22-06-2014
c) Puddling 24-06-2014
d) Manuring 25-06-2014
e) Sowing 25-06-2014
f) Irrigation
1st 25-06-2014
2nd 2-07-2014
3rd 10-07-2014
2. Layout of experiment
Pot establishment 11-07-2014
Pot filling 11-07-2014
3. Puddling 15-07-2014
4. Transplanting 15-07-2014
5. Fertilizer application
a) Basal application of NPK 15-07-2014
b) Deep placement of coated urea 22-07-2014
8.
a)
b)
Weed management (hand weeding)
1st hoeing
2nd hoeing
30-07-2014
30-07-2014
20-08-2014
9. Irrigation
Every day the pots were irrigated to maintain
suitable moisture content in soil for plant growth
10. Harvesting 01-10-2014
3.6.1 Nursery raising
A small plot of 25 m2 was selected for growing rice seedlings. The nursery
area was ploughed thrice, levelled and desired seedbed was prepared. Soil moisture
condition favourable to seedling growth was provided and bed was uniformly
fertilized. Certified seeds of rice genotype ‘NDR-97” were soaked in water for 12
hours and subsequently sown in the nursery on puddled bed by broadcast method
Materials and Methods
~ 32 ~
adopting the recommended seed rate of 30 kg ha-1. Small amount of water was
sprinkled over the nursery area for two days and thereafter it was drained off.
Optimum soil moisture was maintained in the nursery for good growth of seedlings.
3.6.2 Pot preparation
Good soil preparation provides chance for good growth of rice plant. The soil
of the pots was puddled manually by using kudal, levelled with a thin film of water at
its surface.
3.6.3 Transplanting
One day before transplanting, nursery bed was irrigated to maintain soft soil to
prevent tearing of seedling roots. Seedlings were uprooted carefully from the nursery
bed and 25 days old seedlings were transplanted in the puddled pots at the rate of two
to three seedlings hill-1and four hills pot-1. Row spacing of 15 cm and hill-to-hill
distance 15 cm were maintained. Gap filling was done, if required.
3.6.4 Irrigation
Irrigation water was supplied to the experimental crop as per needs at different
stages of crop growth.
3.6.5 Weed management
Management of weeds was done only by hand weeding at 15 DAT and 35
DAT.
3.6.6 Harvesting
The crop was harvested at maturity stage, when most of the panicles turned
golden yellow. All four hills of each treatment were harvested separately. The
harvested hills were carefully bundled, tagged and fresh weight was taken.
Materials and Methods
~ 33 ~
3.6.7 Threshing
Threshing was done pot wise. The bundles of each plot were threshed
separately with the help of thresher and grains thus collected were cleaned and
weighed with the help of spring balance separately for each pot and computed to g
hill-1 at 12% moisture level. The straw yield was also recorded pot wise and
calculated in terms of g hill-1.
3.7 Observations on coated urea fertilizers
3.7.1 Soil nitrogen analysis
Soil nitrogen content was recorded at 3 days intervals after application of
coated urea fertilizers upto 41 days after placement of fertilizers. Soil samples were
collected from soil between four hills where coated urea fertilizers were deep placed
to assess the nitrogen releasing from these products in unit time interval.
3.8 Biometric observations
For recording biometric observations at a regular interval of 30 days i.e. 30th,
60th day after transplanting and at harvest. Yield attributes and yield were studied
before and after harvesting.
3.9.1 Growth attributes
3.9.1.1 Plant height
Height of individual hill from each pot was measured with the help of meter
scale from the base of the plant to the tip of upper most leaf of the plant before panicle
emergence and upto the tip of panicle after heading, averaged and expressed as
average plant height in cm.
3.9.1.2 Number of tillers per hill
Total tillers per hill were countedfrom each pot separately and expressed as
average number of tillers per plant.
Materials and Methods
~ 34 ~
3.9.1.3 Number of functional leaves per hill
The number of green leaves (3/4 of leaf length) were counted from all four
hills of each pot separately, averaged and expressed as average number of leaves per
hill.
3.9.1.4 Chlorophyll content
Chlorophyll content of 10 randomly selected fully grown leaves per pot was
recorded by using SPAD meter (soil-plant analysis development).
3.9.2Yield attributes
3.9.2.1 Number of panicles per hill
Numbers of panicle per hill were counted from all four hills of each pot
separately and was expressed in average number of panicles per hill.
3.9.2.2 Panicle length (cm)
From each pot 10 panicles were selected randomlyand the panicle length was
measured from base to the tip of the panicle and the average length of panicle was
calculated.
3.9.2.3 Grains per panicle
The panicles used for computing length were threshed separately for each plot
and the number of grains per panicle was worked out.
3.9.2.4 Test weight (g)
Grain samples were obtained from cleaned produce of each pot and 1000
grains were counted and weighed.
3.9.2.5 Grain and straw yield (g/hill)
Grain and straw yield were recorded from the hills harvested from each pot.
The threshing of individual hill was done separately and the weight of grain and straw
Materials and Methods
~ 35 ~
were recorded for each hill after drying to bring the moisture content at a standard
level of 12% and then converted into g hill-1.
For recording straw yield, grain yield was deducted from dry weight of each
hill. The weight thus obtained, converted into g hill-1.
3.9.2.6 Harvest Index (HI)
The harvest index was computed in terms of grain yield expressed as
percentage of biological yield (grain + straw) based on the per hectare yields as
described by Donald, (1968).
Harvest Index (HI) =
Economic yield (grain) [kg ha-1]
× 100
Biological yield (grain+straw) [kg ha-1]
3.9.2.7 Biological yield:
Biological yield = Grain yield + straw yield
3.9.3 Plant and grain analyses
For chemical analysis plant samples, as per treatment, were taken at harvest of
crop. Samples were cleaned properly by repeated washing followed by 0.1N HCl,
solutions. Finally all the samples were subjected to washing by doubled distilled
water. Samples were then dried under shade followed by hot air oven at 60± 10 C for
48 hrs. After drying samples were weighted and grounded in Willey’s Mill as par
treatment separately and stored in butters paper cover. Sample was than subjected to
chemical analysis for Nitrogen, Phosphorus and Potassium content.
The nitrogen content in grain and straw was estimated by modified Kjeldhal
method, while phosphorus was estimated by Vandomolybdate method and potassium
by flame photometer method.
Materials and Methods
~ 36 ~
Table 3.5 Method of chemical analysis
Analysis Method Reference
Nitrogen Kjeldahl method Jackson, 1973
Phosphorus Vanadomolybdo-phosphoric acid yellow
colour method
Jackson, 1973
Potassium Flame photometer method Jackson, 1973
3.9.3.1 Nutrient (N, P, K) removal by grain and straw (g hill-1)
Nutrient (N, P and K) removal by grain and straw of rice crop was calculated
in g hill-1 in relation to dry matter production ha-1 by using the following formula.
3.9.3.2 Protein content in grain
The percentage of protein content in grain was estimated by multiplying
nitrogen content by a factor of 6.25 (A.O.A.C., 1960).
Protein content in grain (%) = N content in grain (%) × 6.25
3.10 Statistical analysis
All the data obtained from the experiment were put to statistical analysis by
method of ‘Analysis of Variance’ as suggested by (Gomez and Gomez, 1984).
The significant differences were checked with the help of F-test (Variance
ratio) of Fisher (1958). In order to compare the mean value of treatment, standard
error and critical values were calculated. The following formula was used for standard
error, critical difference and coefficient of variance estimations.
Removal (g hill-1) = Nutrient (%) in grain/straw × grain/straw yield (g hill-1)
100
Materials and Methods
~ 37 ~
a) SEm± = √Ems/r
b) CD = 2Ems × t5% or SEd × t5%
r
b) C.V. (%) = √EmsGM
× 100
Where,
DF = Degree of freedom,
C.D. = Critical difference,
S.S. = Sum of square,
Ems = Error mean square,
r = Number of replication
C.V. = Coefficient of variance,
S.Em± = Standard error of mean
t5%= t value at 5% level of significance from T table at corresponding error df.
Chapter IV
EXPERIMENTAL FINDINGS
In this chapter an attempt has been made to present the experimental findings
of different characters related to the crop and soil nitrogen status at specific interval
after application of urea during the course of investigation. The experiment entitled
“Effect of polymer coated urea on the growth and yield of rice (Oryza sativa L.)”
was conducted in pot during the kharif season of 2014 at the Agricultural Research
Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar
Pradesh (India).
During the course of investigation, observations on nitrogen analysis of soil with
different coated urea fertilizers such as polymer coated urea (single coated & double
coated), neem coated urea, sulphur coated urea and urea supergranules were recorded
at 3 days interval after deep placement. Different characters of rice were also recorded
at 30, 60 days after transplanting and at harvest. Observations pertaining to yield and
yield attributes were recorded at harvest. Statistically analyzed data have been
organized in relevant tables with graphical illustrations provided wherever necessary.
4.1 Studies on nitrogen
The nitrogen status of soil with different coated urea and urea supergranules
were recorded at 3 days interval after application. Uptake of nitrogen, phosphorus and
potassium by crop were recorded at harvest.
The study on nitrogen analysis of soil after application of coated urea
presented in Table 4.1 revealed that there was significant difference among treatments
on N content in soil at all the dates of observation that was taken at every 3 days
interval after the deep placement of urea particles. There was no significant difference
between polymer coated urea having both single layer and double layer in N content
just after the application up to 23 days and then significant difference in terms of
release rate was observed. Double layer polymer coated urea released N with slower
rate than single layer coated PCU, but availability of nitrogen was there, for quite
longer period.
Experimental Findings
~39~
The data clearly revealed that N status of soil analyzed at 3 days interval
significantly increased till maturity of crop with application of polymer coated urea,
while plant showed deficiency in later stage of growth with simple urea. Initially
polymer coated urea (PCU) released N slowly upto 3 week thereafter rapid release
was noticed, whereas in case of urea supergranules most of N was released within 20
days after application.
4.2 Observation on crop
4.2.1 Plant height (cm)
The data related to the plant height as influenced by various treatments
presented in the Table 4.2 revealed that the plant height increased consistently with
the advancement of crop age. The treatments significantly influenced the plant height
at all the stages of crop growth.
The data clearly showed that maximum plant height was recorded with the
application of double layer polymer coated urea [PCU (double layer)]. Plant height
was found minimum with uncoated urea i.e. urea supergranules, whereas neem coated
urea remained at par with sulphur coated and polymer coated urea (single layer) at
harvest.
4.2.2 Number of tillers per hill
The data pertaining to the effect of coated urea on number of tillers hill-1 have
been presented in Table 4.3.
In general, the tiller production per hill increased up to 60 days after
transplanting and there after it declined due to mortality of younger tillers irrespective
of the treatment.
It is apparent from data that the nitrogen source significantly differed among
themselves with respect to tiller production at different stages of observation. The
number of tillers increased significantly with availability of nitrogen to plant from
tiller formation to reproductive stage and was found maximum with polymer coated
Experimental Findings
~40~
urea (double layer) followed by single layer polymer coated urea (PCU, single layer),
neem coated urea (NCU) and sulphur coated urea (SCU) respectively, while minimum
was found with deep placed urea supergranules. Neem coated urea was superior to
urea supergranules, but remained at par with sulphur coated urea and PCU (single
layer) during entire growth period.
There were 24.33, 16.47, 16.02 and 9.09 per cent increase in tiller number with
deep placement of PCU (double coated) over uncoated control (urea supergranules),
sulphur coated urea, neem coated urea and PCU (single coated) respectively at
harvest.
4.2.3 Number of leaves per hill
It is evident from data (Table 4.4) that number of leaves increased as the
growth progressed up to 60 days. However, the rate of increase in number of leaves
remained slower from 30-60 DAT after which it decreased markedly at harvest.
The no. of leaves hill-1 was found to be significantly different among the
sources at different stages of observation. A review of data clearly indicated that deep
placement of PCU (double coated) @ 2g at the center of four hills produced
significantly more number of leaves per hill over all the treatments during the whole
crop period. Number of leaves per hill with neem coated urea (NCU) was at par with
sulphur coated urea (SCU) at 30 & 60 DAT and with polymer coated urea (single
layer) at 30 DAT and harvest. More number of green leaves was observed with coated
urea till maturity of crop, whereas plant with uncoated urea showed yellowish leaves
at later stage of growth.
4.2.4 Chlorophyll content (SPAD)
The data related to the content of chlorophyll in leaves as influenced by
various treatments are presented in Table 4.5.
A cursory glance of data revealed that maximum content of chlorophyll was at
30 DAT as compared to other crop growth stages i.e. at 60 DAT and harvest.
However, there was no significant difference among treatments in chlorophyll content
Experimental Findings
~41~
of leaves at 30 DAT, but chlorophyll content in leaf was significantly higher with
PCU (double layer) than other treatments at harvesting.
4.2.5 Fresh weight (g hill-1)
The data related to the fresh weight of hill at harvest as influenced by various
treatments are presented in Table 4.6.
Perusal of data revealed marked increase in fresh weight of crop per hill at
harvest. The fresh weight of crop was found to be maximum with polymer coated
urea (double layer) over all other treatments.
The fresh weight of crop was 143.96, 157.5, 138.36 and 133.32 and 121.21
g hill-1 with application of PCU (single coated), PCU (double coated), neem coated
urea and sulphur coated urea and untreated control respectively.
4.2.6 Dry weight (g hill-1)
The data related to the dry weight per hill as influenced by various treatments
are presented in Table 4.6
It is apparent from the data that the dry matter production differed
significantly due to different source of N fertilizers. PCU was significantly superior to
all other treatments in respect to dry matter accumulation.
The perusal of data indicated that deep placed polymer coated urea (PCU)
showed higher dry matter accumulation compared to other treatments. Neem coated
urea remained at par with sulphur coated urea with 105.21 & 102.71 g hill-1 dry
weight respectively, at harvesting. Minimum dry matter accumulation was recorded
with urea super granules (93.89 g hill-1).
There were 32.41, 20.24, 12.06 and 9.39 per cent increase in dry weight with
coated urea viz. double layer polymer coated urea (PCU), single layer polymer coated
urea, NCU (neem coated urea) and SCU (sulphur coated urea) respectively over
uncoated urea super granules.
Experimental Findings
~42~
4.2.7 Yield attributes
4.2.7.1 Number of effective tillers per hill
Data pertaining to the effect of source of nitrogen on number of effective
tillers per hill have been presented in Table 4.3.
Perusal of data shows that number of effective tillers significantly increased
with coated nitrogenous fertilizer as compared to uncoated urea. Deep placement of
double coated PCU fertilizer recorded highest number of effective tillers per hill,
while neem coated urea remained at par with sulphur coated urea and PCU (single
layer).
4.2.7.2 Panicle length (cm)
The data on panicle length (cm) are presented in Table 4.7. Data shows that
sources of N have significant effect on length of panicle.
Data shows that application of polymer coated urea (double layered) recorded
maximum panicle length (20.14 cm) but at par with PCU (single layered) and neem
coated urea. The length of panicle was found to be minimum in uncoated urea
supergranules (18.26 cm) which was at par with the sulphur coated urea fertilizer
(18.52 cm).
4.2.7.3 Panicle weight (g panicle-1)
The data on panicle weight shows that sources of N have significant effect on
weight of panicle (Table 4.7).
An examination of data revealed that highest value of panicle weight was
observed with deep placed double layer polymer coated urea followed by single layer
polymer coated urea, neem coated urea, sulphur coated urea and urea supergranules
respectively.
Experimental Findings
~43~
4.2.7.4 Number of grains per panicle
A critical study of the data on number of grains per panicle has been presented
in Table 4.7.
Perusal of data reveals that the maximum number grains panicle-1 was
recorded with the treatment in which polymer coated urea was deep placed at the
center of four hills. All the coated urea treatment recorded significantly higher
number of grains per panicle than uncoated urea (urea supergranule). No significant
difference was observed between neem coated and sulphur coated urea in producing
grains per panicle.
Deep placed PCU both double layer and single layer increased 16.07 and 9.38
per cent grains per panicle respectively over uncoated urea.
4.2.7.5 Test weight (g)
A critical study of the data presented in Table 4.7 revealed that the treatments
did not have any significant effect on test weight of grain. There was no significant
difference of coated urea on 1000 grain weight than the uncoated urea.
4.2.8 Effect of treatments on yield
The data pertaining to effect of different sources of N on grain and straw yield
expressed in g hill-1 (Table 4.8).
An examination of data revealed that polymer coated urea showed superiority
over uncoated urea in respect of grain, straw and total biological yield.
4.2.8.1 Grain yield (g hill-1)
The data pertaining to effect of different treatments on grain yield in g hill-1
presented in Table 4.8.
The highest grain yield per hill (54.39 g/hill) was recorded in the treatment in
which double layered polymer coated urea was deep placed at the mid of four hills,
Experimental Findings
~44~
while minimum grain yield (39.43 g/hill) was recorded in uncoated urea. Overall
23.89, 37.94, 14.53 and 10.58 per cent increase in yield was observed by PCU (single
layered), PCU (double layered), NCU and SCU respectively over control (uncoated
urea supergranules).
4.2.8.2 Straw yield (g hill-1)
A cursory glance of data on straw yield showed similar results to the grain
yield as presented in Table 4.8.
Deep placement of polymer coated urea (double layer) showed superiority
over untreated control in respect of straw yield, whereas neem coated urea treatment
remained at par with sulphur coated urea only. The increase in straw yield by the
application of PCU (single layer) and PCU (double layer) over urea supergranules
was found to be 17.59% and 28.41% respectively.
4.2.8.3 Total biological yield (g hill-1)
The data pertaining to effect of different treatments on total biological yield in
g hill-1 presented in Table 4.8.
Perusal of data reveals that maximum biological yield was found in double
layer polymer coated urea application which was at par with PCU (single layer) and
significantly superior to other treatments, while deep placement of neem coated urea
was at par with sulphur coated urea. Lowest biological yield was recorded with urea
supergranules.
There were 32.41, 20.24, 12.06 and 9.39 per cent increase in total biological
yield with double layer PCU over all other treatments urea supergranules, sulphur
coated urea, neem coated urea and polymer coated urea (single layer) respectively.
4.2.8.4 Harvest Index (%)
The data on harvest index as influenced by various sources of nitrogen have
been presented in Table 4.8.
Experimental Findings
~45~
Among all the treatments, maximum harvest index (43.75%) was recorded
with the application of polymer coated urea (double layer), but it remained
statistically at par with all other treatments.
4.2.9 NPK content and uptake by crop
Data related to NPK content (%) in grain and straw and their uptake by crop
(g hill-1) at harvest presented in Table 4.9, 4.10 and 4.11.
Improvement in nutrient content and their uptake by the application of
polymer coated urea was found to be higher than uncoated urea.
4.2.9.1 Nitrogen content and uptake by crop
The data pertaining to N content (%) in grain and straw and its uptake by crop
(g hill-1) presented in Table 4.9, 4.10 and 4.11.
An examination of data revealed that nitrogen content and uptake of nitrogen
was maximum with polymer coated urea which remained significantly superior to
uncoated urea (USG). The percent N content in grain with PCU (double layer) was
highest (1.13%). Uptake of nitrogen by plant was 1.18, 1.33, 1.05, 1.00 and 0.88
g hill-1 with the application of polymer coated urea (single layer), polymer coated urea
(double layer), neem coated urea, sulphur coated urea and urea supergranules
respectively.
4.2.9.2 Phosphorus content and uptake by crop
The data on P content (%) in grain and straw and uptake by crop (g hill-1)
presented in Table 4.9, 4.10 and 4.11 indicate that uptake of phosphorus by hills was
affected by sources of nitrogen. Maximum uptake of P was observed in polymer
coated urea (double layer).
Phosphorus uptake expressed in g hill-1 was 0.20, 0.17, 0.15 and 0.14 with
PCU (double layer), polymer coated urea (single layer), SCU and NCU respectively.
Experimental Findings
~46~
4.2.9.3 Potassium content and uptake by crop
A cursory glance of data pertaining to K content (%) in grain and straw and its
uptake by crop (g hill-1) has been presented in Table 4.9, 4.10 and 4.11.
It is revealed that potassium content of grain and straw was affected by coated
urea. The highest uptake of potassium by grain and straw was observed under the
polymer coated urea (double layer) followed by polymer coated urea (single layer),
neem coated urea (NCU) and sulphur coated urea (SCU) respectively, while minimum
was observed in uncoated urea supergranules (USG). The per cent increase in uptake
of potassium by plant was 47.78 and 31.11 with PCU (double layer) and PCU (single
layer) respectively over control.
4.2.10 Protein content in grain (%)
Summary of the data on protein content in grain of rice as influenced by
different treatments have been given in Table 4.12.
Significant variation in protein content in grain was obtained due to different
sources of N. Application of PCU (double layer) @ 2g per four hills showed
significantly higher protein content than other treatments except single layer PCU
(U1). Minimum content of protein was found with urea supergranules (6.83%).
Table 4.1: Effect of different treatments on nitrogen content in soil at 3 days intervals
Treatments
N content in soil (kg ha-1)
2
DAA
5
DAA
8
DAA
11
DAA
14
DAA
17
DAA
20
DAA
23
DAA
26
DAA
29
DAA
32
DAA
35
DAA
38
DAA
41
DAA
U0 224.47 227.60 234.50 247.35 258.33 267.73 273.38 267.73 259.26 254.25 251.11 246.41 241.40 235.75
U1 219.76 219.76 220.39 222.59 223.21 225.72 227.60 230.11 235.13 242.96 251.43 262.72 267.11 271.49
U2 219.76 219.76 219.76 221.96 222.59 223.21 226.35 228.23 231.37 235.75 241.40 249.55 255.82 262.09
U3 219.76 222.59 225.09 228.86 234.50 241.39 247.67 255.82 263.03 269.30 274.31 269.30 260.21 252.68
U4 221.33 223.84 226.97 230.74 238.57 246.41 256.13 266.79 273.37 266.79 259.58 252.99 243.91 238.89
SEM 0.30 0.24 0.56 0.65 0.44 0.68 0.71 0.62 0.53 0.60 0.61 0.49 0.40 0.44
CD 1.28 1.02 2.41 2.82 1.92 2.92 3.05 2.68 2.28 2.59 2.65 2.12 1.71 1.91
U0 = Urea supergranules Initial nitrogen content in soil = 175 kg ha-1
U1 = Polymer coated urea (single layer) N applied by fertilizer = 102 kg ha-1
U2 = Polymer coated urea (double layer) DAA = Days after application
U3 = Neem coated urea
U4= Sulphur coated urea
Fig. 4.1: Effect of different treatments on nitrogen content in soil at 3 days intervals
200
210
220
230
240
250
260
270
280
2 5 8 11 14 17 20 23 26 29 32 35 38 41
U0 (Urea supergranules) U1 PCU (single layer) U2 PCU (double layer)
U3 (Neem coated urea) U4 (Sulphur coated urea)
N c
on
ten
t in
so
il(k
g h
a-1)
Days after application
Table 4.2: Effect of different treatments on plant height
Treatments Plant height (cm)
30 DAT 60 DAT Harvesting
Urea supergranules (U0) 48.82 73.41 74.97
Polymer coated urea (single layer) U1 51.24 77.82 79.48
Polymer coated urea (double layer) U2 52.93 79.89 81.35
Neem coated urea (U3) 50.93 76.21 78.28
Sulphur coated urea (U4) 50.23 75.69 78.36
SEm± 0.34 0.34 0.26
CD (P=0.05) 1.45 1.45 1.10
Fig. 4.2: Effect of different treatments on plant height
0
10
20
30
40
50
60
70
80
90
U0 (Ureasupergranules)
U1 PCU (singlelayered)
U2 PCU (doublelayered)
U3 (Neemcoated urea)
U4 (Sulphurcoated urea)
30 DAT 60 DAT Harvesting
Pla
nt
hei
ght
(cm
)
U0 (Urea U1 PCU (single U2 PCU (double U3 (Neem U4 (Sulphur supergranules) layer) layer) coated urea) coated urea)
Table 4.3: Effect of different treatments on number of tillers
Treatments Tillers hill-1
30 DAT 60 DAT Harvesting
Urea supergranules (U0) 16.47 19.11 16.89
Polymer coated urea (single layer) U1 18.50 21.69 19.25
Polymer coated urea (double layer) U2 19.81 23.17 21.00
Neem coated urea (U3) 18.35 20.97 18.10
Sulphur coated urea (U4) 18.28 20.33 18.03
SEm± 0.23 0.22 0.32
CD (P=0.05) 0.98 0.94 1.39
Fig. 4.3: Effect of different treatments on number of tillers
0
5
10
15
20
25
U0 (Urea supergranules)
U1 PCU (singlelayered)
U2 PCU (doublelayered)
U3 (Neemcoated urea)
U4 (Sulphurcoated urea)
30 DAT 60 DAT Harvesting
Tille
rs h
ill-1
U0 (Urea U1 PCU (single U2 PCU (double U3 (Neem U4 (Sulphur supergranules) layer) layer) coated urea) coated urea)
Table 4.4: Effect of coated urea on number of leaves
Treatments Leaves hill-1
30 DAT 60 DAT Harvesting
Urea supergranules (U0) 80.50 85.50 50.35
Polymer coated urea (single layer) U1 91.25 97.50 60.44
Polymer coated urea (double layer) U2 95.00 102.00 64.29
Neem coated urea (U3) 87.50 93.00 59.15
Sulphur coated urea (U4) 85.25 92.50 53.42
SEm± 0.72 0.95 0.60
CD (P=0.05) 3.11 4.12 2.60
Fig. 4.4: Effect of different treatments on chlorophyll content (SPAD)
0
5
10
15
20
25
30
35
40
45
50
U0 (Ureasupergranules)
U1 PCU (singlelayered)
U2 PCU (doublelayered)
U3 (Neemcoated urea)
U4 (Sulphurcoated urea)
30 DAT 60 DAT Harvesting
Ch
loro
ph
yll c
on
ten
t (S
PA
D)
U0 (Urea U1 PCU (single U2 PCU (double U3 (Neem U4 (Sulphur supergranules) layer) layer) coated urea) coated urea)
Table 4.5: Effect of different treatments on chlorophyll content (SPAD)
Treatments Chlorophyll content (SPAD)
30 DAT 60 DAT Harvesting
Urea supergranules (U0) 42.88 38.23 28.70
Polymer coated urea (single layer) U1 43.10 40.25 31.45
Polymer coated urea (double layer) U2 44.05 41.38 34.05
Neem coated urea (U3) 43.03 40.01 31.13
Sulphur coated urea (U4) 42.10 39.98 29.85
SEm± 0.68 0.30 0.24
CD (P=0.05) NS 1.30 1.02
Fig. 4.5: Effect of different treatment on grain, straw, total biological yield
0
20
40
60
80
100
120
140
U0 (Urea supergranules)
U1 PCU (singlelayered)
U2 PCU(doublelayered)
U3 (Neemcoated urea)
U4 (Sulphurcoated urea)
grain yield straw yield Total biological yield
Yie
ld (
g h
ill-1
)
U0 (Urea U1 PCU (single U2 PCU (double U3 (Neem U4 (Sulphur supergranules) layer) layer) coated urea) coated urea)
Table 4.6: Effect of different treatments on fresh and dry weight per hill at
harvest.
Treatments Fresh weight
(g hill-1)
Dry weight(g
hill-1)
Urea supergranules (U0) 121.21 93.89
Polymer coated urea (single layer) U1 143.96 112.90
Polymer coated urea (double layer) U2 157.50 124.32
Neem coated urea (U3) 138.36 105.21
Sulphur coated urea (U4) 133.32 102.71
SEm± 1.23 1.43
CD (P=0.05) 5.30 6.20
Table 4.7: Effect of different treatments on length and weight of panicle,
number of grain per panicle and test weight
Treatments
Panicle
length
(cm)
Weight
panicle-1 (g)
Grains
panicle-1
Test
weight
(g)
Urea supergranules (U0) 18.26 2.31 93.38 21.66
Polymer coated urea (single layer) U1 19.61 2.56 102.14 22.28
Polymer coated urea (double layer) U2 20.14 2.61 108.39 22.73
Neem coated urea (U3) 19.26 2.50 100.49 22.11
Sulphur coated urea (U4) 18.52 2.42 99.13 21.94
SEm± 0.22 0.02 0.75 0.20
CD (P=0.05) 0.93 0.07 3.23 NS
Table 4.8: Effect of different treatment on grain, straw, total biological yield and harvest
index
Treatments
Grain
yield
(g hill-1)
Straw
yield
(g hill-1)
Total
biological
yield (g hill-1)
Harvest
Index
(%)
Urea supergranules (U0) 39.43 54.46 93.89 42.00
Polymer coated urea (single layer) U1 48.85 64.04 112.90 43.25
Polymer coated urea (double layer) U2 54.39 69.93 124.32 43.75
Neem coated urea (U3) 45.16 60.06 105.21 42.92
Sulphur coated urea (U4) 43.60 59.11 102.71 42.41
SEm± 0.83 0.74 1.43 0.35
CD (P=0.05) 3.60 3.21 6.20 NS
Table 4.9: Effect of coated urea on nitrogen, phosphorus and potassium content in
grain
Treatments
Nutrient content in grain (%)
Nitrogen Phosphorus Potassium
Urea supergranules (U0) 1.07 0.20 0.10
Polymer coated urea (single layer) U1 1.12 0.23 0.11
Polymer coated urea (double layer) U2 1.13 0.25 0.11
Neem coated urea (U3) 1.10 0.22 0.11
Sulphur coated urea (U4) 1.10 0.21 0.10
SEm± 0.003 0.01 0.002
CD (P=0.05) 0.01 0.02 0.01
Table 4.10: Effect of coated urea on nitrogen, phosphorus and potassium
content in straw
Treatments
Nutrient content in straw (%)
Nitrogen Phosphorus Potassium
Urea supergranules (U0) 0.88 0.06 0.46
Polymer coated urea (single layer) U1 0.97 0.09 0.46
Polymer coated urea (double layer) U2 1.02 0.09 0.47
Neem coated urea (U3) 0.95 0.09 0.43
Sulphur coated urea (U4) 0.88 0.08 0.41
SEm± 0.01 0.005 0.005
CD (P=0.05) 0.05 0.02 0.02
Table 4.11: Effect of different treatment on nutrient uptake by hill
Treatments Nutrient uptake (g hill-1)
Nitrogen Phosphorus Potassium
Urea supergranules (U0) 0.90 0.11 0.29
Polymer coated urea (single layer) U1 1.18 0.17 0.35
Polymer coated urea (double layer) U2 1.33 0.20 0.39
Neem coated urea (U3) 1.05 0.15 0.30
Sulphur coated urea (U4) 1.00 0.14 0.29
SEm± 0.02 0.005 0.005
CD (P=0.05) 0.08 0.02 0.02
Table 4.12: Effect of coated urea on protein content in grain.
Treatments Protein content in grain (%)
Urea supergranules (U0) 6.70
Polymer coated urea (single layer) U1 7.00
Polymer coated urea (double layer) U2 7.03
Neem coated urea (U3) 6.84
Sulphur coated urea (U4) 6.83
SEm± 0.02
CD (P=0.05) 0.07
Chapter V
DISCUSSION
Rice (Oryza sativa L.) is the most important cereal crop of world both in
respect to area and production. India ranks first in area and second in production after
china in the world. The scope for increasing the production by cultivating more land,
particularly in developing countries like India is limited and hence, the other
alternative lies in increasing the production per unit area. To exploit the yield
potential of a variety, the inputs which can bring about a massive increase in
production are fertilizers and irrigation.
Among the various production inputs fertilizer nutrient is the most limiting
factor in agricultural land. By judicious use of these inputs, the same land can yield
many times more per hectare than is not only essential to maximize the production per
unit area and per unit time, but also to improve the productivity of every unit of other
costly inputs like water, labour, seed etc.
The present investigation entitled “Effect of polymer coated urea on plant
growth and yield of rice (Oryza sativa L.)” was conducted at the Agriculture
Research Farm, Institute of Agriculture Sciences, Banaras Hindu University, Varanasi
(U.P.) during the kharif season of 2014.
The findings of the experiment reported in the previous chapter have been
discussed and illustrated in this text with the help of suitable reasoning in the light of
literature available on the subject and principles of crop production.
5.1 Effect of weather on crop
Results of field investigations are affected by weather conditions. The effect of
weather during the crop season is one of the most important factors which determine
the extent of crop growth, development and overall performance. Every crop has its
own cardinal temperature, humidity, rainfall, sunshine duration and other weather
condition for higher yields. But, these optimal conditions seldom prevail. A slight
alteration in weather condition may adversely affect overall growth and development.
Discussion
~48~
Rice is basically a crop of warm regions of the tropics and sub tropics.
Summerfield et al. (1974) showed that temperature during cropping season have
significant influence on vegetative and reproductive phases. The mean maximum
temperature ranging from 23.60C to 43.40C and minimum temperature between
24.20C to 28.70C during the cropping period provide average condition for crop
growth.
The meteorological data (Table 3.1 and depicted in Fig. 3.1) during the course
of experimentation showed that in general weather conditions were congenial for
normal growth of rice crops.
5.2 Effect of weather on polymer coated urea (PCU)
The soil N analyses at 3 days interval after the deep placement of coated urea
envisage that N released from coated urea was influenced by weather elements
specially temperature and soil moisture content.
There was no marked difference in temperature during the experimentation
and therefore no fluctuation was noticed in release rate of nitrogen with respect to
temperature, but slight decline was noticed during 21-26 days after application (DAA)
due to decrease in temperature; after which sharp increase in N content of soil and
release rate found in the observations taken at 26, 29, 32 and 35 DAA due to higher
soil temperature in respective week. Wang et al. (2011) reported that at 250C lower
temperature small portion of N released from coated particle as compared to higher
temperature 1000 C when 100 % N release within some hours.
Moisture is another factor that affects the rate, pattern and duration of release
of nitrogen from coated urea (Fujinuma et al., 2009; Shaviv, 2005). However, since
the trail was conducted under irrigated condition, the effect of moisture remained
neutral for all the treatments.
5.3 Effect of polymer coated urea (PCU) on crop growth
Crop growth is the product of interaction of environmental factors, genetic
constituents and agronomic measures for providing suitable environmental condition
to ensure optimum plant growth.
Discussion
~49~
Nitrogen is a component of many important organic compounds ranging
from protein to nucleic acids. It is an integral part of chlorophyll, which is the primary
absorber of light energy needed for photosynthesis. Plant growth is adversely affected
due to deficiency of nitrogen as it is a constituent of proteins, chlorophyll and
vitamins. Deficiency of N causes stunted growth, chlorosis of lower leaves and less
tillering in cereals.
Results of experiment showed that polymer coated urea had significant effect
on plant growth and yield (Table 4.2-4.8). Better growth and higher grain and straw
yield were obtained in polymer coated urea compared to urea supergranules. Plant
height, tiller number, dry matter production, grains per panicle and grain yield
increased by use of polymer coated urea over uncoated urea i.e. 8.51%, 24.33%,
32.41%, 16.07% and 23-37% respectively. Nutrient uptake by plant and N recovery
was noticed higher with coated urea compared to uncoated urea. The reason behind
this was the slow release pattern of nitrogen from PCU (polymer coated urea) which
synchronized with N release to plant nutrient demand for better plant growth and crop
yield by reducing nitrogen losses and environmental pollution (Kanno, 2008).
5.3.1 Growth characters
Growth parameters which include plant height, number of tillers per plant and
dry matter accumulation were significantly influenced by different sources of N. In
the investigation, it was observed that polymer coated urea caused significant effect
on all the growth parameters viz. plant height, tiller production, leaf number and dry
matter accumulation at all the growth stages (Table 4.2-4.6).
Maximum plant height was recorded with application of double layer polymer
coated urea, which was at par with single polymer coated urea (U1) at 30 DAS &
harvest. It was significantly superior to rest of treatments. Similar results were
recorded by Nash et al. (2013); Pinpeangchan and Wanapu (2015). Nitrogen released
from polymer coated urea granules matching to plant nutrient demand improved plant
height and induce better plant growth.
The number of tillers were found maximum in deep-placed polymer coated
urea (double layer), which remained at par with PCU (single layer). The increase in
Discussion
~50~
number of tillers under PCU (double layer) was observed because of increasing
availability of nitrogen till the maturity of crop.
Polymer coated urea controls the release of N from coated particles and
delays the availability of nitrogen to the crop and continuously produces number of
green leaves upto maturity. Higher number of green leaves and maximum chlorophyll
content were observed with polymer coated urea (double layer) at the later stages of
crop growth. Hatfield and Parkin (2014) observed increased greenness as well as
duration of green leaf area in the corn crop upto grain-filling stage with the use of
fertilizers like PCU, stabilized fertilizers and nitrification inhibitors.
Dry matter production differed significantly due to different sources of N at
all the growth stages. Polymer coated urea (double layer) was significantly superior to
rest of treatments, whereas neem coated urea was found statistically at par with
sulphur coated urea at harvest. Lowest dry matter production was recorded with
uncoated urea (urea supergranule). Several researchers (Singh et al., 2004; Pack et al.,
2007; Sahota et al., 2010) also reported marked increase in dry matter accumulation
with polymer coated urea in different crops.
Increase in plant height, tillers per plant, leaf greenness, leaf weight, LAI and
plant dry weight with the application of PCU was also reported by Nash et al. (2013);
Strey and Christians (2013); Hatfield and Parkin (2014).
5.3.2 Yield attributes
Yield attributes, which determine yield, is the resultant effect of the
vegetative development of the plant. All the attributes of yield including effective
tillers per hill, panicle length, panicle weight, grain panicle-1 were significantly
influenced by sources of N (Table 4.7).
All the coated urea treatments significantly influenced the yield attributes as
compared to uncoated control. Maximum number of effective tillers was counted in
deep placed polymer coated urea (double layer) due to availability of N for longer
period of time. About 14-24% increase in number of panicle was noticed with
polymer coated urea at harvest. The number of effective tillers per hill was increased
Discussion
~51~
because of increase in availability of N to the crop during tillering to reproductive
stage.
With the application of PCU (double layer) higher panicle length and weight,
grains per panicle and test weight were recorded. The result indicated that increase in
yield contributing characters of plants treated with PCU was due to availability of
adequate amount of N during reproductive and grain filling stages. Significant
increase in number of grains per panicle in PCU over conventional urea was also
reported by Patil et al. (2010). Singh et al. (2004) also found similar results with the
use of polyolefin resin coating slow release Fe fertilizers.
5.3.3 Yield
Yield is the result of coordinated interplay of various growth characters
(Ramamoorthy et al., 1998). Grain and straw yield in terms of g hill-1 were
significantly influenced by different coated urea fertilizers (Table 4.8). The treatments
with higher yield attributing characters produced higher grain and straw yields.
Polymer coated urea fertilizers (both single layer and double layer) showed
greater efficacy in increasing the grain and straw yield in comparison to other
treatments. However all coated urea had significant effect in increasing grain and
straw yields due to availability of nitrogen in adequate amount for longer duration.
Ma et al. (2012) also reported 10.4-16.5% increase in grain yield with sulphur and
polymer coated urea over traditional urea.
The grain and straw yields in term of q ha-1 were found to be the highest
(24.17 and 31.08 q ha-1 respectively) under polymer coated urea (double layer) as
compared to urea supergranules with 17.52 and 24.02 q ha-1. Carreres et al. (2003),
Slaton et al. (2009) and Golden et al. (2009) observed significant increase in grain
yield with PCU than conventional urea. The results of experiments conducted on
potato revealed an increase in tuber yield with PCU over control/conventional N
fertilizers like urea, ammonium sulfate [AS] & ammonium nitrate [AN] (Zvomuya
et al., 2003 and Pack et al., 2007).
Discussion
~52~
5.3.4 Nutrient uptake by plant
In general N content in plant tissue ranges from 1-4% with average 1.5%
total nutrient content. Nitrogen is an essential nutrient which directly affects plant
growth and plant nutrient uptake. The nitrogen uptake by plant and its accumulation
in grain and straw are therefore affected by availability of N in later growth stage
(Carreres et al., 2003).
The nutrient uptake (N, P and K) by plant (grain and straw) varied
significantly with the application of different sources of N (Table 4.9-4.11). Highest
N, P and K content in grain as well as maximum nutrient uptake by plant was
recorded in polymer coated urea (double layer), while neem coated urea remained at
par with sulphur coated urea. The maximum uptake of nitrogen by the plants is
induced by synchronized release of nitrogen from coated urea (Kaneta et al., 1994).
PCU application in saturated paddy field enhances fertilizer use efficiency,
NUE as well as nitrogen recovery percentage by ensuring better uptake and
translocation of nitrogen released from polymer coated urea (Kanno et al., 2000;
Kanno, 2008). Higher nitrogen use efficiency in PCU may be related to release of N
in the soil-plant system according to plant demand and consequently higher
utilization. Fageria (2011) reported 25% higher NUE at polymer coated urea
compared to conventional urea.
Reviews related to PCU fertilizers confirm it as best fertilizer in lowland
paddy. PCU (32% and 40% N) and isobutylidenediurea (IBDU) application shortly
before flooding improved total N uptake and recovery efficiency compared to the
conventional fertilizer application (Carreres et al., 2003).
5.3.5 Protein content
N is an important component for most of the amino acids (Swan, 1971a).
The protein content of grain is therefore affected by availability of nitrogen during
grain formation. The quality of grain like protein and starch are also affected by
polymer coated urea. Greater protein content of grain obtained from the application of
polymer coated urea (Farmaha and Sims, 2013).
Discussion
~53~
The result of the research on protein content of grain (Table 4.12) showed that
higher % of protein could be obtained by polymer coated urea (both single and double
layer). Minimum protein content noticed in urea supergranules, was perhaps due to
unavailability of N during grain formation and grain-filling period. Ma et al. (2012)
also reported 5.8-18.9% and 0.3-1.4% increase in protein and starch content of grain
in wheat with the application of polymer coated urea over traditional urea.
Chapter VI
SUMMARY AND CONCLUSION
In this chapter an attempt has been made to summarize the results and draw a
valid conclusion based on the significant findings of the present investigation entitled
“Effect of polymer coated urea on the growth and yield of rice (Oryza sativa L.)”.
The investigation was conducted during the Kharif season of 2014 at Research Farm,
Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh
(India) with the following objectives:
1. To find out N content in soil at 3 days interval upto 41 days after application
with deep placement of different coated urea like polymer coated urea, neem
coated urea, sulphur coated urea and urea supergranules.
2. To find out their effect on plant growth, yield and nutrient uptake by rice.
To fulfill the above objectives, field experiment was laid out in randomized
complete block design (RCBD) with five treatments replicated four times. Paddy
variety NDR-97 was grown as test crop by adopting a spacing of 15×15 cm2. The soil
of the experimental field was Gangetic alluvial and sandy clay loam in texture with
pH 7.4, 0.38% organic carbon, 175 kg, 18 kg and 199.6 kg ha-1 of available nitrogen,
phosphorus and potassium respectively. A uniform fertilizer dose of 102-60-60 kg N,
P2O5, K2O ha-1 was applied by basal application and deep placement of 2g coated urea
a week after transplanting.
Observations were recorded on N content of soil at 3 days interval after deep
placement and on crop attributes viz. plant height, tiller number, functional leaves,
chlorophyll content, yield attributes of rice and yield and nutrient content and uptake
by crop.
The salient results of the present study are summarized below:
The negligible or small change in soil N content just after application of
polymer coated urea was noticed. However, N content in soil (rate of release)
Summary and Conclusion
~55~
gradually increased with the passage of time and the most delayed release was
found with polymer coated urea.
The growth parameters viz. plant height, number of tillers hill-1 and dry matter
accumulation of rice were maximum with the deep placed PCU (double layer).
Higher chlorophyll content was observed with polymer coated urea than other
treatments at all the stages of growth.
Significantly improved yield attributes like number of panicles per hill, weight
of panicle, grains per panicle and test weight were found with double layer
polymer coated urea compare to uncoated urea granule.
Grain, straw and total biological yield were found maximum with polymer
coated urea (double layer).
The maximum uptake of N, P and K by crop was recorded with PCU (double
layer) followed by PCU (single layer) and minimum with urea supergranules.
CONCLUSION
On the basis of results summarized above, it can be concluded that the release
rate of nitrogen and soil nitrogen content gradually increased upto 41 days with the
application of polymer coated urea. It also has significant effect on growth,
development and production on rice crop under puddled condition.
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Baligar, V.C., (2015) Nitrogen use efficiency in plant: An overview. In: Rakshit,
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