reduced tillage and residue management programs in

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Reduced tillage and residue management programsin sugarcane (Saccharum spp. hybrids)Wilson Elie JudiceLouisiana State University and Agricultural and Mechanical College, [email protected]

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REDUCED TILLAGE AND RESIDUE MANAGEMENTPROGRAMS IN SUGARCANE (SACCHARUM SPP. HYBRIDS)

A Thesis

Submitted to the Graduate Faculty of theLouisiana State University and

Agricultural and Mechanical Collegein partial fulfillment of the

requirements for the degree ofMaster of Science

in

The Department of Agronomy and Environmental Management

byWilson E. Judice

B.S., Louisiana State University, 2003August 2005

ii

ACKNOWLEDGEMENTS

First of all I would like to thank God for all he has done for me. Without his presence I

would truly be lost. You have carried me when I could not have continued on my own.

Secondly, I would like to thank my parents Robert and Carolyn Judice. You have always

supported me in everything I have done in more ways than I can count. Your influence in my

life is what has contributed to my success and all that I have accomplished. I hope that one

day my children will look up to me as much as I look up to both of you. You have both been

a great example to me not only as parents, but as Christians, community members, and as a

couple. Dad, you and Mom instilled in me the work ethic that has allowed me to be

successful as a student and as an employee. I would also like to thank my son Bennett. You

are the greatest joy of my life and you mean the world to me. Some days spending time with

you has been the only thing that has kept me going. To my siblings Robert, Margaret, Sandi,

and Sheri, you have been an inspiration to me and a shoulder to cry on through troubled times.

To my grandparents, Robert and Mattie Judice, your financial support, love, and dedication to

me has made my education possible, and the late Francis and Wilson Viator, your lives on

earth were and always will be an inspiration to me in every step of my life.

Thanks to Dr. Jim Griffin, the time I have spent in your program has been some of the

most valuable time throughout my education. I can truly say that I learned something every

day I have worked for you. You have been an inspiration not only as a scientist but also as a

person.

To my graduate committee, Dr. Jim Griffin, Dr. Eric Webster, Dr. Donnie Miller, Dr. Ben

Legendre, and Dr. Kenneth Gravois each of you have offered me guidance when it was

needed and I thank you for that.

iii

I would like to thank Dr. Kenneth Gravois and Dr. Keith Bischoff and all of the crew at St.

Gabriel for allowing me the opportunity to work in the sugarcane breeding program while an

undergraduate student. I learned so many valuable lessons during my time there and you

were a family to me away from home.

Dr. Freddie Martin, without your encouragement to pursue a degree in Agronomy I would

not be where I am today. The Agronomy and Environmental Management Department has

been a wonderful place to be a student, both undergraduate and graduate. Your door has

always been open for advice and you always make sure that the students in your department

are taken care of.

There are so many fellow students that I have been blessed to work with. I would like to

thank Jonathan Siebert for recruiting me to work in weed science. To Matt Griffin, Chris

Mudge, Chris Leon, Wei Zhang, Sunny Bottoms, and Justin Hensley, it has been great sharing

an office and getting to know each of you. To John Hebert and Matt Gravois, student workers

like you are priceless to a graduate student. I thank you for accomplishing any task I have

asked you to without complaint. To Joey Boudreaux, you are not only one of the brightest

and hardest working people I know, but you are one of my closest friends. I know that you

and Kelly will go far together. Thanks for everything you have done to help me in my

graduate studies especially being a friend. To Luke Etheredge and Curtis Jones, the two of

you have become like brothers to me. I know there have been times we wanted to kill each

other, but we survived some long hot days and were able to accomplish things as a team.

Luke, remember when you come to rate plots in St. Mary parish to stop by for lunch. Curtis, I

owe you a special thanks for all the assistance you have given me on my thesis, you have

saved both Dr. Griffin and myself plenty of time, effort, and heartache.

iv

I will always remember the time I have spent as a student in the weed science program, the

lessons learned are invaluable and have prepared me to take on anything that the future sends

my way. Thanks to everyone who has been a part of this tremendous learning experience.

v

TABLE OF CONTENTS

ACKNOWLEDGEMENTS ................................................................................................ii

ABSTRACT .......................................................................................................................vi

CHAPTER1 INTRODUCTION...................................................................................................1

RESIDUE MANAGEMENT ..................................................................................1SOIL PROPERTIES AND EROSION....................................................................2WEED CONTROL AND HERBICIDE ACTIVITY..............................................4LITERATURE CITED............................................................................................6

2 SUGARCANE (SACCHARUM SPP. HYBRIDS) PRODUCTION ANDECONOMICS USING REDUCED TILLAGE PROGRAMS..............................12INTRODUCTION.................................................................................................12MATERIALS AND METHODS ..........................................................................15RESULTS AND DISCUSSION............................................................................19LITERATURE CITED..........................................................................................34

3 SUGARCANE (SACCHARUM SPP. HYBRIDS) RESIDUE MANAGEMENTAND REDUCED TILLAGE PROGRAMS..........................................................38INTRODUCTION.................................................................................................38MATERIALS AND METHODS ..........................................................................40RESULTS AND DISCUSSION............................................................................44LITERATURE CITED..........................................................................................57

4 SUMMARY ..........................................................................................................60

APPENDIX: THREE WAY INTERACTION MEANS FOR TILLAGE STUDY 2.......66

VITA..................................................................................................................................69

vi

ABSTRACT

The effect of tillage andweed control programs on ‘LCP 85-384’ sugarcane (Saccharum

spp. hybrids) growth, yield, and economics was evaluated during the 2002 and 2003 growing

seasons. When row shoulders and middles were not tilled in March soil temperature in the

non-cultivated sugarcane drill early in the growing season was equal to that where March

tillage was performed. Sugarcane and sugar yield were each equivalent for the full season

tillage (off-bar tillage in March plus layby tillage in May) and the no-till program. Weeds

were effectively controlled with a March application of hexazinone at 0.59 kg ai/ha plus

diuron at 2.10 kg ai/ha. For the no-till program with herbicide banded in March compared

with full season tillage, net return was increased $32.56/ha. In a subsequent study conducted

at five locations sugar yield was increased 8.6% and net return was increased $152.68/ha

when sugarcane was not tilled in March. Sugar yield was increased 8.0% and net return was

increased $143.88/ha when layby tillage in May was eliminated. Mechanical removal of

crop residue remaining on the soil surface three weeks after harvest of LCP 85-384 with a

combine harvester was compared with burning. Tillage efficiency in March was not reduced

when the residue was mechanically removed from the row top and placed in the row middle.

Sugar yield was reduced an average of 7.9% when sugarcane residue was not removed

compared with mechanical removal or burning in December. Research was expanded to also

include mechanical removal of sugarcane residue in January, February, or March. For each

residue removal treatment off-bar tillage in March (with or without) was included. Allowing

crop residue to remain on the soil surface until March reduced both early season sugarcane

height and shoot population when compared with December residue removal. Sugar yield

was equivalent when crop residue was removed in December by burning or mechanically

vii

and averaged 8,670 kg/ha. Delaying mechanical removal of residue until February or March

decreased sugar yields an average of around 13% compared with December burn or

mechanical removal.

1

CHAPTER 1

INTRODUCTION

Conservation tillage practices can range from no-till to some level of reduced tillage. In

2001 in the U.S. reduced tillage was used on almost 42 million hectares representing 36.6% of

planted cropland (Anonymous 2002). Conservation tillage has become an integral component

of sustainable agriculture reducing both input costs and soil loss (Lal et al. 1990). Other

benefits include conservation of moisture and elimination of extensive land preparation prior

to planting. Reduced tillage and no-till systems are also means to conserve energy, reduce

soil erosion, reduce labor costs, improve soil productivity, and improve profitability without

sacrificing yield (Cavanaugh 1988; Coats and Thacker 1997; Coats 2001; Colwick and Barker

1975; Dick et al. 1991; Dick and VanDoren 1985; Kennedy and Hutchinson 2001; Triplett

and Van Doren 1977; Vetsch and Randall 2002; Vyn et al. 1998; Wagger and Denton 1992;

Wall and Stobbe, 1984). Australian sugarcane (Saccharum spp. hybrids) farmers have used

no-till to reduce tractor hours, fuel consumption, and maintenance costs without adversely

affecting productivity (Anonymous 1991). Researchers in Cuba reported no differences in

sugarcane yield between traditional cultivation and reduced tillage practices (Pear et al. 1992).

RESIDUE MANAGEMENT

In a conservation tillage program crop residue is an integral part of a management system.

In the mid 1990’s, Louisiana sugarcane growers began usingcombine harvesters instead of

the traditional soldier (whole stalk) harvesters. Since chopper harvesters give growers the

option to harvest the crop green, significant crop residue is deposited on the soil surface.

When feasible this residue is removed by burning, however, the environmental and social

implications of burning sugarcane residue make alternative removal methods desirable.

2

Residue can be beneficial in suppressing weeds, conserving moisture, and reducing soil loss.

Conservation tillage systems can also reduce fuel costs, soil water evaporation, and soil

temperature fluctuations (Dick et al. 1991; Triplett and Van Doren 1977; Wagger and Denton

1992; Wall and Stobbe 1984). Reductions in early season corn growth and, in some cases,

final grain yield have been reported and attributed to lower soil temperature under a no-till

system (Vyn and Raimbault 1993). Residue cover is a major factor in determining soil

temperature and availability of soil moisture (Beyaert et al. 2002). Viator et al. (2005)

reported that while sugarcane residue provided insulation during winter months it also

decreased soil temperature in the spring by 2 to 3 ºC. This reduction in soil temperature

combined with a 7 to 8% increase in soil moisture delayed emergence of the stubble

sugarcane crop. Azooz et al. (1995) reported that removing residues from a 30-cm-wide area

over the row at planting resulted in soil thermal and moisture conditions equivalent to a

conventional tillage system. Removal of residue from the area where the new crop will

emerge by way of strip tillage has enhanced corn (Zea mays L.) emergence (Fortin 1993;

Kaspar et al. 1990; Kaspar and Erbach 1998; Swan et al. 1994; Vetsch and Randal 2000;

Wolkowski 2000). In sugarcane, residue remaining in the field following a green harvest can

reduce crop emergence as well as growth and yield (Richard 1999). An alternative to

removing all the residue by burning may be to remove residue only from the area where the

new crop will emerge, which has been successful in other crops.

SOIL PROPERTIES AND EROSION

Residue remaining on the soil surface can stabilize soil and reduce erosion. Previous

research has shown that a minimum of 20% residue cover on the soil surface is necessary to

reduce soil erosion (Beyaert et al. 2002; Moldenhauer et al. 1983). Researchers in Australia

3

found that incorporating sugarcane residue decreased soil loss compared to tillage of bare soil

(Glanville et al. 1997). Improved soil physical properties associated with no-till planting have

been documented (Griffith et al. 1986). Research has shown that soil carbon and nitrogen

levels decline after years of cultivation (Hass et al. 1957; Tiessen et al. 1982; Young et al.

1960) and that this decline can be minimized or eliminated by conservation tillage practices

(Dick 1983; Lamb et al. 1985). Distribution of soil carbon and nitrogen in soils under no-till

management is affected because of residue accumulation on the soil surface and enhanced

microbial activity (Doran 1980). No-till conditions result in greater microbial biomass and

greater carbon and nitrogen mineralization potential (Doran 1980; Staley et al. 1988; Wood

1990). In India, sugarcane growth and yield was improved when residue remained in the field

and was attributed to residual nutrients in the soil released from decaying residue as well as a

reduced bulk density (Srivastava 2003). Soil strength in the upper 15 cm of the soil profile

was lower for no-till compared with conventional tillage (Kennedy and Hutchinson 2001).

No-till plots also had less soil impedance, indicating improved soil structure and the potential

for improved root growth. Colwick and Barker (1975) found that minimum tillage reduced

soil compaction. Soil compaction increases with increased wheel traffic and is considered

detrimental to crop production (Coats 2001).

Tillage systems also can impact soil moisture status because tillage influences infiltration,

runoff, evaporation, and soil water storage (Dao 1993; Unger and Cassel 1991; Unger and

Fulton 1989). Vetsch and Randall (2002) found that residue present using zone-till or strip-

till (tillage of an area only where the new crop will be planted) programs was as effective as

no-till in reducing soil erosion. Halvorson et al. (2002) found that as tillage intensity

decreased in an annual cropping system soil organic carbon sequestration, total soil nitrogen,

4

and total crop residue returned to the soil increased. The benefit of increasing soil organic

carbon not only improved soil structure and water-nutrient relationships, but also the ability to

store carbon in the soil to reduce atmospheric CO2, a greenhouse gas (Janzen et al. 1999; Lal

et al. 1998b, 1999). Reduced tillage has also resulted in lower pH, increased cation exchange

capacity, and increased calcium and magnesium availability (Hickman 2002). In a soil that

was normally poorly drained and where movement of nutrients was limited, no-till increased

macroporosity and water infiltration. In reduced–tillage and no-till fallow systems there can

be as much water stored in the soil by May as there is in a conventional tillage system three to

four months later (Farahani et al. 1998). Glanville et al. (1997) found that reduced tillage and

no-till greatly reduced soil erosion in Australian sugarcane fields, and that increased erosion

potential was due to the detachment of soil aggregates by tillage action.

WEED CONTROL AND HERBICIDE ACTIVITY

Weed control is a major concern for growers when switching to conservation tillage.

Conservation tillage and weed control are intimately linked and the ability to control weeds,

herbicide cost, and benefits of conservation tillage must all be considered when determining

the feasibility of a conservation tillage program (Koskinen and McWhorter 1986). The

sustainability of diverse reduced tillage systems is dependant on the development of

economical and effective weed management programs (Derksen et al. 2002). Reduced tillage

systems can influence the population dynamics of perennial and annual weed species

(Gebhardt et al. 1985). Perennial weeds are particularly troublesome after only two to three

years of conservation tillage (Witt 1984). Triplett et al. (1983) listed the following perennial

weeds as particularly problematic in reduced tillage systems: johnsongrass (Sorghum

halepense L. Pers.), bermudagrass (Cynodon dactylon L. Pers.), and purple nutsedge (Cyperus

5

rotundus L.). Primary and secondary tillage are generally effective in controlling weeds,

however, when converting to a conservation tillage system, herbicides and crop-management

strategies are the only means to control weeds (Gebhardt et al. 1985). The replacement of

tillage with herbicides for weed control has made it possible to develop reduced-tillage and

no-till production systems in winter wheat (Triticum aestivum L.) (Halvorson et al. 2002).

Increased surface residue in conservation tillage systems can affect herbicide activity by

influencing herbicide adsorption, movement, persistence, and efficacy. Surface residue can

also affect weed seed distribution, viability, and dormancy (Gebhardt et al. 1985). Crop

residue management can influence the level of weed control. Fisk et al. (2001) found that

when cover crop residue was left on the soil surface, density and dry weight of perennial

weeds were 35 and 75% lower, respectively, compared with no residue. Winter wheat residue

reduced weed seedling emergence in corn by 45% (Crutchfield et al. 1986) and weed biomass

by 60% (Wicks et al. 1994). The level of weed suppression is directly related to the amount

of residue on the soil surface (Crutchfield et al. 1986; Vander Vorst et al. 1983). Although

beneficial in respect to weed control, plant residue on the soil surface can be detrimental to

emergence and growth of the crop. Fisk et al. (2001) reported that density of annual weeds

was reduced as much as 78% and dry weight was reduced as much as 80% when corn was

planted following a cover crop compared with no cover crop, but crop yield was also reduced.

The effect of cover crop residue on both weeds and the crop are related to change in soil

temperature, increase in soil moisture, release of allelopathic chemicals, and physical

impediments (Facelli and Pickett 1991; Teasdale 1996; Teasdale and Mohler 1993). Teasdale

(1996) reported that cover crops may reduce herbicide inputs resulting in a shift toward use of

postemergence herbicides. Although cover crops reduced weed competition, chemical control

6

measures were still needed (Curran et al. 1994; Johnson et al. 1993; Teasdale 1996; Yenish et

al. 1996).

Herbicide persistence and efficacy in soil are controlled by various soil processes,

including adsorption, decomposition, and movement. These processes are directly or

indirectly affected by soil properties such as soil moisture, temperature, pH, organic matter,

and microbial populations (Guenzi 1974), all of which are affected by tillage systems (Blevins

et al. 1983). Increased soil moisture (up to field capacity) generally increases microbial

degradation of herbicides which would reduce their persistence and activity (Hurle and

Walker 1980). However reductions in temperature associated with conservation tillage may

reduce microbial activity and therefore increase herbicide persistence (Hurle and Walker

1980). Lack of tillage causes ammonium fertilizer to be nitrified near the soil surface

resulting in decreased pH. Soil pH can have varying effects on herbicide adsorption,

chemical and microbial decomposition, and movement in soil. The persistence and activity of

some herbicides can be reduced by increased adsorption or degradation due to low soil pH

(Koskinen and McWhorter 1986). In conservation tillage systems, organic matter in the upper

portion of the soil is increased; this increase in organic matter may also affect herbicide

persistence and activity. For a given amount of herbicide, increased organic matter content

reduces herbicide effectiveness by increasing adsorption of the herbicide in soil and

interception of herbicide by surface residue (Koskinen and McWhorter 1986).

LITERATURE CITED

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7

Azooz, R. H., B. Lowery, and T. C. Daniel. 1995. Tillage and residue management influenceon corn growth. Soil and Tillage Res. 33:215-227.

Beyaert, R. P., J. W. Schott, and P. H. White. 2002. Tillage effect on corn (Zea mays L.)production in a coarse-textured soil in southern Ontario. Agron. J. 94:767-774.

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Cavanaugh, P. 1988. Making minimum-till work in cotton. California-Arizona CottonJanuary:4-7.

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Triplett, G. B., J. R. Abernathy, C. R. Fenster, W. Flinchum, D. L. Linscott, E. L. Robinson,L. Standifer, and J. D. Walker. 1983. Weed control for reduced tillage systems (AD-FO-2279). Extension Service, U.S. Dept. Agr., Washington D.C. 8 pp.

Unger, P. W. and D. K. Cassel. 1991. Tillage implement disturbance effects on soil propertiesrelated to soil and water conservation: A literature review. Soil and Tillage Res. 19:363-382.

Unger, P. W. and L. J. Fulton. 1989. Conventional and no-tillage effects on upper root zonesoil conditions. Soil and Tillage Res. 16:337-344.

Vander Vorst, P. B., G. A. Wicks, and O. C. Burnside. 1983. Weed control in a winter wheat-corn-ecofarming rotation. Agron. J. 75:507-511.

Vetsch, J. A. and G. W. Randall. 2000. Enhancing no-tillage systems for corn with starterfertilizers, row cleaners, and nitrogen placement method. Agron. J. 92:309-315.

Vetsch, J. A. and G. W. Randall. 2002. Corn production as affected by tillage system andstarter fertilizer. Agron. J. 94:532-540.

Viator, R. P., R. M. Johnson, E. P. Richard, Jr. 2005. Management of the post-harvest residueblanket. The Sugar Bull. 83 (5):11-12.

Vyn, T. J. and B. A. Raimbault. 1993. Long-term effect of five tillage systems on cornresponse and soil structure. Agron. J. 85:1074-1079.

Vyn, T. J., G. Opoku, and C. J. Swanton. 1998. Residue management and minimum tillagesystems for soybeans following wheat. Agron. J. 90:131-138.

Wagger, M. G. and H. P. Denton. 1992. Crop and tillage rotations: Grain yield, residue coverand soil water. Soil Sci. Soc. Am. J. 56:1233-1237.

Wall, D. A. and E. H. Stobbe. 1984. The effect of tillage on soil temperature and corn (Zeamays L.) growth in Manitoba, Can. J. Plant Sci. 64:59-67.

11

Wicks, G. A., P. T. Nordquist, G. E. Hanson, and J. W. Schmidt. 1994. Influence of winterwheat (Triticum aestivum L.) cultivars on weed control in sorghum (Sorghum bicolor).Weed Sci. 42:27-34.

Witt, W. W. 1984. Response of weeds and herbicides under no-tillage conditions. In No-Tillage Agriculture: Principles and Practices. R. E. Phillips and S. H. Phillips, Editors. VanNostrand Reinhold, New York, 1984. pp. 152-170.

Wolkowski, R. P. 2000. Row-placed fertilizer for maize grown with an in-row crop residuemanagement system in southern Wisconsin. Soil and Tillage Res. 54:55-62.

Wood, C. W. 1990. Nitrogen and carbon cycling in no-till dryland agroecosystems. Ph.D.dissertation. Colorado State University, Fort Collins, CO.

Yenish, J. P., A. D. Worsham, and A. C York, 1996. Cover crops for herbicide replacement inno-tillage corn (Zea mays L.). Weed Technol. 10:815-821.

Young, R. A., J. C. Zubriski, and E. B. Norum. 1960. Influence of long time fertilitymanagement practices on chemical and physical properties of Fargo Clay. Soil Sci. Soc.Am. Proc. 24:124-128.

12

CHAPTER 2

SUGARCANE (SACCHARUM SPP. HYBRIDS) PRODUCTION AND ECONOMICSUSING REDUCED TILLAGE PROGRAMS

INTRODUCTION

Sugarcane (Saccharum spp. hybrids) is a perennial crop and in Louisiana four to six

harvests are made from a single planting. The first harvest year is the plant cane crop and

consecutive years are stubble crops. Throughout the crop cycle sugarcane row shoulders and

middles are intensively cultivated to promote crop growth, eliminate ruts, incorporate

fertilizer, and control weeds. In a typical sugarcane production system, three tillage

operations are performed during the growing season. The first operation in mid- to late-

March is known as off-bar tillage, the second tillage operation is conducted when fertilizer is

applied in mid-April, and the third tillage operation is at layby in mid- to late-May. In all

cases an area on the row top around 60 cm wide is not disturbed. Although, some form of

reduced tillage is used in most agronomic crops, sugarcane growers have been slow to adopt

reduced tillage practices because of concerns over the negative effect on crop growth and on

weed control.

Conservation tillage programs can range from no-till to some level of reduced tillage. In

2001 in the U.S., reduced tillage was used on almost 42 million hectares representing 36.6%

of planted cropland (Anonymous 2002). Conservation tillage has become an integral

component of sustainable agriculture reducing both input costs and soil loss (Lal et al. 1990).

Reduced tillage and no-till systems also are means to conserve energy, reduce soil erosion,

reduce labor costs, improve soil productivity, and improve profitability without sacrificing

yield (Coats and Thacker 1997; Dick and Van Doren 1985; Dick et al. 1991; Kennedy and

13

Hutchinson 2001; Triplett and Van Doren 1977; Vetsch and Randall 2002; Vyn et al. 1998;

Wagger and Denton 1992; Wall and Stobbe, 1984). Australian sugarcane farmers have used

no-till to reduce tractor hours, fuel consumption, and maintenance costs without adversely

affecting productivity (Anonymous 1991). In Cuba no differences in sugarcane yield between

traditionally cultivated plots and reduced tillage plots were observed (Pear et al. 1992).

Improved soil physical properties associated with no-tillage have been documented

(Griffith et al. 1986). Research has shown that soil carbon and nitrogen levels decline after

years of cultivation (Tiessen et al. 1982) and that this decline can be minimized or eliminated

by conservation practices (Dick 1983; Lamb et al. 1985). Distribution of soil carbon and

nitrogen in soils under no-till management is affected because of residue accumulation on the

soil surface and enhanced microbial activity (Doran 1980). Soil strength in the upper 15 cm

of the soil profile was lower for no-till compared with conventional tillage (Kennedy and

Hutchinson 2001). No-till plots also had less soil impedance, indicating improved soil

structure and the potential for improved root growth.

Tillage systems also can impact soil moisture status because tillage influences infiltration,

runoff, evaporation, and soil water storage (Dao 1993; Unger and Fulton 1989; Unger and

Cassel 1991). In reduced tillage and no-till fallow systems there can be as much water stored

in the soil by May as there is in a conventional tillage system three to four months later

(Farahani et al. 1998). Vetsch and Randall (2002) found that residue present in no-till and in

reduced tillage (zone-till and strip-till where only the area where the new crop will be planted

is cultivated) was sufficient to minimize erosion. Conservation tillage systems can reduce the

volume of soil loss by an average of about 25% (Baker and Johnson 1983). In Australia,

Glanville et al. (1997) found that reduced tillage and no-till greatly reduced soil erosion in

14

sugarcane fields, and that increased erosion potential was due to the detachment of soil

aggregates by tillage action.

Conservation tillage and weed control are intimately linked and the ability to control

weeds, herbicide cost, and the benefits of conservation tillage must all be considered when

determining the feasibility of a conservation tillage program (Koskinen and McWhorter

1986). The replacement of tillage with herbicides for weed control has made it possible to

develop reduced tillage and no-till winter wheat production systems (Halvorson et al. 2002).

Increased surface residue in conservation tillage systems can affect herbicide activity by

influencing herbicide adsorption, movement, persistence, and efficacy. These processes are

directly or indirectly affected by soil properties such as soil moisture, temperature, pH,

organic matter, and microbial populations (Guenzi 1974), all of which are affected by tillage

systems (Blevins et al. 1983).

Increased soil moisture (up to field capacity) generally increases microbial degradation of

herbicides which would reduce herbicide persistence and activity (Hurle and Walker 1980).

At typical seed placement depths, soil under conservation tillage can be 3 to 4º C cooler than

under conventional tillage (Blevins et al. 1983). Reduction in soil temperature associated

with conservation tillage may reduce microbial activity and therefore increase herbicide

persistence (Hurle and Walker 1980). In conservation tillage systems organic matter in the

upper portion of the soil profile is increased, and may affect herbicide persistence and

activity.

The objectives of this research were to evaluate no-tillage and reduced tillage programs in

sugarcane in regard to crop growth and yield and weed management and to compare

15

economics associated with use of reduced tillage programs compared with a full tillage

conventional program.

MATERIALS AND METHODS

Tillage Study 1. Reduced tillage experiments were conducted in 2002 and 2003 at the St.

Gabriel Research Station in St. Gabriel, LA. The soil type was a Commerce silt loam (fine-

silty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquept) with 1.01% organic

matter and pH of 5.9. The experimental design was a randomized complete block with a

three-factor factorial arrangement of treatments and four replications. Factor A represented

off-bar spring tillage March 25, 2002, and March 26, 2003 (with or without), and factor B

represented layby tillage May 17, 2002, and May 20, 2003 (with or without). For the tillage

operations the row shoulders and middles were mechanically worked using disk gang

cultivators but an area approximately 61 cm wide on the row top was not disturbed. This

operation is typical of sugarcane production in Louisiana. Factor C represented early season

herbicide application method (banded or broadcast). A premix of 0.59 kg ai/ha hexazinone

and 2.10 kg ai/ha diuron1 was applied March 25, 2002, and March 26, 2003, using a tractor

mounted compressed air sprayer calibrated to deliver 140 L/ha at 228 kPa. Banded

applications were made to a 91 cm area on the row top. Typically in Louisiana herbicide is

banded following off-bar spring tillage. The sugarcane variety used in these experiments was

‘LCP 85-384’. Plant cane (first production year) in 2002 and first stubble (second production

year) in 2003. In the stubble cane experiment, crop residue deposited on the field at harvest

had decomposed during the winter such that it was not a factor affecting spring growth of

sugarcane.

1 DuPont K4 ®, DuPont Crop Protection Walker’s Mill, Barley Mill Plaza Wilmington, Delaware 19880-0038.

16

Temperature probes connected to a data logger2 were placed in the center of the sugarcane

drill at a 5 cm depth and soil temperature was recorded from March 20 to May 30 in 2002 and

from March 26 to May 30, 2003. Data collected represent average daily soil temperature.

Sugarcane shoot population was determined in April and plant height, measured from the soil

surface to the top of the sugarcane canopy, was recorded in April and May (just prior to layby

cultivation). Sugarcane stalk population and height were also determined in August. Stalk

height was measured from the soil surface to the collar of the youngest leaf on five randomly

selected stalks. Plots were harvested on October 24, 2002, and November 21, 2003, using a

commercial single-row combine harvester and a dump wagon fitted with three weigh cells

capable of being tared between plots to determine total sugarcane yield. Before harvesting,

samples of 10 randomly selected stalks were hand harvested and weighed to determine

average stalk weight. Stalk samples were then crushed and the juice was extracted for

analysis of theoretical recoverable sugar using standard methodology (Chen and Chou 1993).

Sugar yield was calculated by multiplying theoretical recoverable sugar by sugarcane yield3.

Tillage Study 2. In 2004, research was expanded to include five locations throughout the

sugarcane growing region of Louisiana. The five locations were in Assumption, St. James, St.

Mary, St. Martin, and Iberia parishes. Specific information for the experimental sites to

include sugarcane variety and production year and soil type and classification, pH, and

organic matter is presented in Table 2.1. In the stubble cane experiments crop residue

deposited on the field at harvest had decomposed during the winter such that it was not a

factor affecting growth of sugarcane. The experimental design was a randomized complete

2 Hobo ® Data Logger, Onset Computer Corporation, P.O. Box 3450, Pocasset, MA 02559-345C.3 Sugar content of stalks derived from theoretical recoverable sugar expressed as kilograms of sugar per 1,000 kgof sugarcane.

17

Table 2.1. Location and soils information for Tillage Study 2.Parish Sugarcane variety Sugarcane crop (production year) Soil type Soil classification pH Organic matter (%)

Assumption HoCP 85-845 Second stubble (3) Commerce silt loam fine-silty, mixed, superactive,

nonacid, thermic

Fluvaquentic Endoaquepts

6.06 1.16

Iberia LCP 85-384 Plant cane (1) Patoutville silt loam fine-silty, mixed, superactive,

thermic Aeric Epiaqualfs

5.12 1.52

St. James LCP 85-384 Plant cane (1) Commerce silty clay loam fine-silty, mixed, superactive,

nonacid, thermic

Fluvaquentic Endoaquepts

6.75 1.66

St. Martin LCP 85-384 First stubble (2) Dundee very fine sandy loam fine-silty, mixed, active,

thermic Typic Endoaqualfs

6.24 0.91

St. Mary LCP 85-384 Plant cane (1) Buxin silty clay loam a very-fine, smectitic, thermic

Aquic Hapluderts

5.85 1.46

a Part of the Buxin-Portland-Perry soil complex. The Buxin series predominates and is therefore described.

18

block with a three factor factorial arrangement of treatments and two replications were

included at each site. Factor A represented off-bar spring tillage March 9 to 12, 2004 (with or

without), and factor B represented layby tillage May 17 to 27, 2004 (with or without). For the

tillage operations the row shoulders and middles were worked mechanically using disk gang

cultivators but an area approximately 61 cm wide on the row top was not disturbed. Factor C

represented the herbicide programs of pendimethalin at 2.77 kg ai/ha plus metribuzin at 1.26

kg ai/ha or a premix of hexazinone plus diuron at 0.59 kg/ha and 2.10 kg/ha and herbicides

were applied between March 9 and 12. Herbicides were applied broadcast using a tractor

mounted compressed air sprayer calibrated to deliver 140 L/ha at 207 kpa. Sugarcane

shoot/stalk population and shoot/stalk height were determined as previously described. Plots

were hand harvested in late September and ten randomly selected stalks were weighed to

determine average stalk weight. Sugarcane yield was estimated using stalk weight data and

stalk population data collected in August. Sugar yield was determined as described

previously.

In Tillage Study 1, significant differences in sugar yield among the various tillage

treatments were not observed; and, therefore, sugar yield data could not be used to calculate

gross return. The change in tillage cost (with or without) and herbicide cost (band vs.

broadcast) for the reduced tillage and no tillage treatments were compared with the full tillage

conventional treatment (with spring tillage and with layby tillage) and the change in net return

was calculated. Tillage cost was figured at $16.28 /ha total cost ($8.67 variable and $7.61

fixed) (Breaux and Salassi 2005). Herbicide cost differences were based on application

method (band vs. broadcast) of the premix of hexaxinone plus diuron at $13.60/kg. Spray

19

application cost was not considered since cost was the same whether herbicide was banded or

broadcast.

In Tillage Study 2, a significant interaction between spring tillage and layby tillage was not

observed for sugar yield. However, there were significant spring tillage and layby tillage

main effects. Using the sugar yield data for the spring tillage main effect (with or without

averaged across layby tillage) and for the layby tillage main effect (with or without averaged

across spring tillage) gross return was estimated at 50% (grower share) of yield times $0.44

/kg of sugar. The change in gross return/ha where one tillage operation was eliminated was

used to calculate the change in net return. Tillage cost was figured at $16.28 /ha total cost

($8.67 variable and $7.61 fixed) (Breaux and Salassi 2005).

Data for both tillage studies were subjected to the Mixed Procedure in SAS (SAS 2003).

Years or locations, replications (nested within years or location), and all interactions

containing either of these effects were considered random effects (Carmer et al. 1989). All

other variables (spring tillage, herbicide application method or program, and layby tillage)

were considered fixed effects. Considering year or location as environmental or random

effects permits inferences about treatments to be made over a range of environments (Carmer

et al. 1989; Hager et al. 2003). Type III statistics were used to test the fixed effects. Least

square means were used for mean separation at P≤ 0.05. Letter groupings were converted

using the PDMIX800 macro in SAS (Saxton 1998).

RESULTS AND DISCUSSION

Tillage Study 1. On March 1 of each year sugarcane was beginning to regrow after the

winter dormant period. Even though sugarcane is a tropical crop, in Louisiana winter freezes

are common and can occur as late as March. Average daily soil temperature measured at a 5.

20

10

15

20

25

30

35

3/20/02 3/30/02 4/9/02 4/19/02 4/29/02 5/9/02 5/19/02 5/29/02

Date

Soil

tem

pera

ture

(oC

)

Tillage March 25

No-tillage

10

15

20

25

30

03/26/03 04/05/03 04/15/03 04/25/03 05/05/03 05/15/03 05/25/03

Date

Soil

Tem

pera

ture

(oC

)

Tillage March 26

No-tillage

Figure 2.1. Effect of tillage of row shoulders and middles in late March in LCP 85-384sugarcane on average daily soil temperature in the sugarcane drill in 2002 and 2003 atSt. Gabriel, LA.

2003

2002

21

5

10

15

20

25

30

35

3/20/02 3/30/02 4/9/02 4/19/02 4/29/02 5/9/02 5/19/02 5/29/02

Date

Air

tem

pera

ture

(oC

)

Average daily

Maximum daily

5

10

15

20

25

30

35

03/26/03 04/05/03 04/15/03 04/25/03 05/05/03 05/15/03 05/25/03

Date

Air

Tem

pera

ture

(oC

)

Average daily

Maximum daily

Figure 2.2 Average daily ambient and maximum daily temperatures in 2002 and 2003at St. Gabriel, LA.

2002

2003

22

cm depth within the non cultivated sugarcane drill showed similar response across each

growing season whether sugarcane row middles and shoulders were tilled or not tilled (Figure

2.1). This indicates that contrary to what sugarcane growers may think, spring off-bar tillage

does not promote increased warming of sugarcane beds. The dips in soil temperature

observed early in the season were associated with dips in ambient temperatures (Figure 2.2).

Blevins et al. (1983) reported that under conservation tillage soil temperature can be 3 to 4 oC

cooler when compared with conventional tillage. The difference between this study and the

present study in regard to soil temperature is that in the sugarcane study an area around 60 cm

wide was not disturbed for both the tilled and no-till treatments. Rather, tillage was

performed only on the row shoulders and middles. With sugarcane being a perennial crop

reduced tillage programs would be very different from those implemented in annual crops

planted each year. In essence, in sugarcane, a conventional tillage program would represent

an inverse strip-till program where row sides and middles are tilled but the row top is not

disturbed.

Sugarcane height in April and May (Table 2.2) and sugarcane shoot population in April

(Table 2.3) averaged across years were reflective only of the presence or absence of spring

tillage since layby tillage had not been performed when data were collected. There were no

differences in sugarcane height in April or May or in sugarcane shoot population in April for

the various tillage programs whether hexazinone plus diuron was applied on a band or as a

broadcast treatment. The fact that early season sugarcane emergence and growth were not

hindered when spring off-bar tillage was eliminated further substantiates that spring tillage is

not a necessity. Weed control was excellent where hexaxinone plus diuron was used and

weeds were not a limiting factor in this study. Differences among the tillage treatments and

23

Table 2.2. Effect of banded and broadcast application of herbicide in late March and tillageprograms on sugarcane height across the growing season.

Spring herbicide program a

Hexazinone + diuron (banded) Hexazinone + diuron (broadcast)

Spring tillage/layby tillage b Spring tillage/layby tillage b

+/+ +/- -/+ -/- +/+ +/- -/+ -/-

_______________________________ Sugarcane height in April (cm) _______________________________

27.4 c 27.7 27.4 27.7 27.7 26.9 27.4 27.9

________________________________ Sugarcane height in May (cm) ________________________________

71.9 c 73.2 73.4 73.7 74.7 72.4 73.7 75.9

______________________________ Sugarcane height in August (cm) ______________________________

257.6 c 257.8 256.3 259.1 261.9 260.4 260.6 259.5

a Herbicide at 0.59 + 2.10 kg ai/ha applied in late March to a 91 cm band on a 183 cm row(banded) or broadcasted.

b Tillage programs consisted of spring tillage (late March with (+) or without (-)) and laybytillage (mid to late May with (+) or without (-)). Specific treatments included +/+ = withspring tillage and with layby tillage (full season conventional); +/- = with spring tillage andwithout layby tillage; -/+ = without spring tillage and with layby tillage, and; -/- = withoutspring tillage and without layby tillage (full season no-till).

c Data for each parameter represent an average across 2002 and 2003. For each parameterdifferences among the tillage treatments for the spring herbicide programs were not observed(P≤ 0.05).

24

Table 2.3. Effect of banded and broadcast application of herbicide in late March and tillageprograms on sugarcane shoot and stalk population across the growing season.




+/+ +/- -/+ -/- +/+ +/- -/+ -/-

______________________ Sugarcane shoot population in April (1,000/ha) ______________________

94.2 c 90.7 92.3 88.3 88.3 87.3 92.4 91.2

_____________________ Sugarcane stalk population in August (1,000/ha) _____________________

109.3 c 110.7 109.6 108.7 107.2 113.3 106.7 107.5




25

Table 2.4. Effect of banded and broadcast application of herbicide in late March and tillageprograms on sugarcane yield and sugar yield.




+/+ +/- -/+ -/- +/+ +/- -/+ -/-

____________________________________ Sugarcane yield (1,000 kg/ha) ____________________________________

77.6 c 71.7 72.0 75.6 72.9 67.5 74.4 67.7

___________________________________________ Sugar yield (kg/ha) __________________________________________

8,680 c 8,230 8,280 8,880 8,180 8,110 8,840 8,110




26

herbicide treatments for sugarcane height and stalk population in August were not observed

(Tables 2.2 and 2.3). This same response was also noted for sugarcane yield and sugar yield

(Table 2.4), clearly showing that a no-tillage program (- spring tillage/- layby tillage) was as

effective as a conventional tillage program (+ spring tillage/+ layby tillage). Sugar yield

ranged from 8,110 to 8,880 kg/ha and would be considered excellent. In Australia (Glanville

et al. 1997) and in Cuba (Pear et al. 1992), sugarcane yields were similar for cultivated and

reduced tillage programs. Previous research in Louisiana has shown that reducing tillage in

the plant cane crop had no effect on sugarcane yield, however yield reductions occurred in the

second ratoon crop when at least two tillage operations were not performed (Ricaud and

Arceneaux 1986).

Even though yields for the tillage programs were similar, the elimination of tillage would

reduce input costs and increased net return. The differences in net return were a function of

the difference in tillage costs and in herbicide cost due to application method (Table 2.5).

Compared with a conventional full season tillage program (+/+), tillage cost for a single

tillage operation was reduced $16.28/ha and cost was reduced $32.56/ha when both tillage

operations were eliminated. When herbicide was applied broadcast rather than banded,

herbicide cost increased by $30.49/ha. When either a spring or layby tillage was eliminated

and herbicide was banded net return increased by $16.28/ha. If both off-bar and layby tillage

were eliminated (no-till program) and spring herbicide was banded net return was increased

$32.56/ha. In contrast, when either a spring or layby tillage operation was eliminated and

herbicide was broadcast, net return would decrease $14.21/ha. If both tillage operations were

eliminated and herbicide was broadcast net return would increase only $2.07/ha.

27

Table 2.5. Effect of banded and broadcast application of herbicide in late March and tillage programs on sugar yield and net returnto the grower.



Spring tillage/layby tillage b Spring tillage/layby tillage

+/+ +/- -/+ -/- +/+ +/- -/+ -/-

___________________________________________________________________________ Sugar yield (kg/ha) ___________________________________________________________________________

8,680 c 8,230 8,280 8,880 8,180 8,110 8,840 8,110

______________________________________________ Change in tillage cost/ha. vs. conventional (+/+) treatment ($/ha) d ______________________________________________

- - ($16.28) ($16.28) ($32.56) - - ($16.28) ($16.28) ($32.56)

__________________________________________________ Change in herbicide cost/ha. vs. banded application ($/ha) e __________________________________________________

- - - - - - - - $30.49 $30.49 $30.49 $30.49

_____________________ Change in net return/ha vs. conventional (+/+) tillage treatment and banded herbicide application ($/ha) f _____________________

- - $16.28 $16.28 $32.56 ($30.49) ($14.21) ($14.21) $2.07

a Herbicide at 0.59 + 2.10 kg ai/ha applied in late March to a 91 cm band on a 183 cm row (banded) or broadcasted.b Tillage programs consisted of spring tillage (late March with (+) or without (-)) and layby tillage (mid to late May with (+) or

without (-)). Specific treatments included +/+ = with spring tillage and with layby tillage (full season conventional); +/- = withspring tillage and without layby tillage; -/+ = without spring tillage and with layby tillage, and; -/- = without spring tillage andwithout layby tillage (full season no-till).

c Data for each parameter represent an average across 2002 and 2003. For each parameter differences among the tillagetreatments for the spring herbicide programs were not observed (P≤ 0.05).

d Tillage cost at $16.28 /ha total cost ($8.67 variable and $7.61 fixed). Values in parentheses represent a loss.e Herbicide cost at $13.60/kg. Change in herbicide cost based on a 50% reduction when banded. Spray application cost was not

considered in economic analysis since application cost would be equivalent for both banded and broadcast applications.f Represents change in tillage costs plus change in herbicide cost. Values in parentheses represent a loss.

28

Economic analysis showed that eliminating tillage increase net return when hexazinone

plus diuron is banded, when yield was not affected. However, if herbicide must be applied

broadcast in March to control weeds then any savings due to reduced tillage would be offset

by increased herbicide cost. Use of a less expensive herbicide such as pendimethalin,

however, would make a broadcast application in March more feasible provided that

pendimethalin would reduce weed competition such that yield is not reduced.

Tillage Study 2. Experiments conducted in 2004 at the five locations included a late

March broadcast application of pendimethalin plus metribuzin or hexazinone plus diuron.

There were no differences between March herbicide programs for the parameters measured

and data were averaged across herbicide programs. Weed control was excellent in all

experiments regardless of herbicide program used. A significant interaction between spring

tillage and layby tillage programs was not observed for sugarcane height in April, June, or

August; sugarcane shoot population in April; stalk population in August; or sugarcane and

sugar yield (Tables 2.6, 2.7, and 2.8). There was, however, a significant main effect of spring

tillage on stalk population in August and a significant main effect of spring and layby tillage

on sugar yield. Sugarcane stalk population in August averaged 8.9% more when sugarcane

was not tilled in the spring compared with spring tillage (Table 2.7). Sugar yield averaged

8.6% higher when spring tillage was eliminated and 8.0% higher when layby tillage was

eliminated (Table 2.8). The lower sugarcane stalk population in August and sugar yield

associated with tillage could be attributed to stress due to root pruning and drying of the soil.

In 2004, rainfall was a limiting factor to sugarcane growth in Louisiana especially during the

later part of the growing season and yields throughout most of the industry were affected

29

Table 2.6. Effect of tillage programs on sugarcane height across the 2004 growing season. a

Spring tillage Layby tillage

Spring and layby tillage b Avg. c Avg. d

+/+ +/- -/+ -/- + - + -

___________________________________ Sugarcane height in April (cm) ___________________________________

40.6 e 38.1 39.1 40.9 39.4 40.1 39.9 39.6

___________________________________ Sugarcane height in June (cm) ___________________________________

176.3 e 178.1 178.6 179.8 177.0 179.1 177.3 179.1

__________________________________ Sugarcane height in August (cm) __________________________________

199.4 e 199.1 201.7 201.7 199.1 201.7 200.4 200.7

a Data averaged across spring herbicide programs (pendimethalin at 2.77 kg ai/ha plusmetribuzin at 1.26 kg ai/ha or a premix of hexazinone at 0.59 kg ai/ha plus diuron at 2.10 kgai/ha applied in late March).


c Spring tillage (+) averaged across +/+ with spring tillage and with layby tillage (fullseason conventional) and +/- with spring tillage and without layby tillage. Spring tillage (-)averaged across -/+ without spring tillage and with layby tillage and -/- without spring tillageand without layby tillage (full season no-till).

d Layby tillage (+) averaged across +/+ with spring tillage and with layby tillage (fullseason conventional) and -/+ without spring tillage and with layby tillage. Layby tillage (-)averaged across +/- with spring tillage and without layby tillage and -/- without spring tillageand without layby tillage (full season no-till).

e Data for each parameter averaged across five locations (Assumption, Iberia, St. James, St.Martin, and St. Mary parishes). For each parameter differences among spring and laybytillage means and between spring tillage average means or layby tillage average means werenot observed (P≤ 0.05).

30

Table 2.7. Effect of tillage programs on sugarcane shoot and stalk population across the 2004growing season. a

Spring tillage Layby tilage


+/+ +/- -/+ -/- + - + -

_________________________ Sugarcane shoot population in April (1,000/ha) _________________________

141.8 e 132.8 137.4 143.1 137.3 140.2 139.6 137.9

_________________________ Sugarcane stalk population in August (1,000/ha) ________________________

111.3 e 113.5 124.9 119.8 112.4 b f 122.4 a 118.1 116.7


b Tillage programs consisted of spring tillage (late March with (+) or without (-)) andlayby tillage (mid to late May with (+) or without (-)). Specific treatments included +/+ =with spring tillage and with layby tillage (full season conventional); +/- = with spring tillageand without layby tillage; -/+ = without spring tillage and with layby tillage, and; -/- = withoutspring tillage and without layby tillage (full season no-till).



e Data for each parameter averaged across five locations (Assumption, Iberia, St. James, St.Martin, and St. Mary parishes).

f Spring tillage average means are significantly different (P≤ 0.05).

31

Table 2.8. Effect of tillage programs on sugarcane yield and sugar yield. a

Spring tillage Layby tillage


+/+ +/- -/+ -/- + - + -

___________________________________ Sugarcane yield (1,000 kg/ha) ___________________________________

67.9 e 75.3 75.3 77.3 71.5 76.5 71.7 76.5

__________________________________________ Sugar yield (kg/ha) __________________________________________

6,790 e 7,670 7,710 8,000 7,230 b f 7,850 a 7,250 b f 7,830 a





e Data for each parameter averaged across five locations (Assumption, Iberia, St. James, St.Martin, and St. Mary parishes) for the 2004 growing season.

f Spring tillage average means and layby tillage average means are significantly different (P≤ 0.05).

32

Table 2.9. Effect of tillage programs on sugar yield and net returns to the grower. a

Spring tillage b Layby tillage c

+ - + -

__________________________________________ Sugar yield (kg/ha) __________________________________________

7,230 b d 7,850 a 7,250 b d 7,830 a

____________________________________ Change in sugar yield( kg/ha) ____________________________________

- - 620 - - 580

______________ Change in gross return/ha vs. conventional (+) treatment ($/ha) e ______________

- - $136.40 - - $127.60

______________________________ Average number of tillage operations f ______________________________

1.5 0.5 1.5 0.5

________________________________ Reduction in tillage cost/ha ($/ha) g ________________________________

- - ($16.28) - - ($16.28)

_____________________ Change in net return/ha vs. conventional (+) ($/ha) h _____________________

- - $152.68 - - $143.88

a Data averaged across spring herbicide program (pendimethalin at 2.80 kg ai/ha plusmetribuzin at 1.30 kg ai/ha or a premix of hexazinone at 0.59 kg ai/ha plus diuron at 2.10 kgai/ha applied in late March).

b Spring tillage (+) averaged across +/+ with spring tillage and with layby tillage and +/-with spring tillage and without layby tillage. Spring tillage (-) averaged across -/+ withoutspring tillage and with layby tillage and -/- without spring tillage and without layby tillage.

c Layby tillage (+) averaged across +/+ with spring tillage and with layby tillage (fullseason conventional) and -/+ without spring tillage and with layby tillage. Layby tillage (-)averaged across +/- with spring tillage and without layby tillage and -/- without spring tillageand without layby tillage (full season no-till).

d Data for each parameter averaged across five locations (Assumption, Iberia, St. James, St.Martin, and St. Mary parishes) for the 2004 growing season. Spring tillage average meansand layby tillage average means are significantly different (P≤ 0.05).

e Gross returns/ha estimated at 50% (grower share) of yield times $0.44/kg of sugar.f Calculated from average of spring tillage (late March with (+) or without (-)) and layby

tillage (mid to late May with (+) or without (-)).g Tillage cost at $16.28 /ha total cost ($8.67 variable and $7.61 fixed).h Calculated from change in gross return/ha plus change in tillage cost/ha.

33

(Anonymous 2005). Moisture conservation is a documented advantage of no-till programs

(Farahani et al. 1998).

The differences in net return for the tillage programs were a function of differences in

sugar yield and in tillage costs (Table 2.9). When spring tillage was eliminated sugar yield

was increased 620 kg/ha and net return was increased $152.68/ha. When layby tillage was

eliminated sugar yield was increased 580 kg/ha and net return was increased $143.88/ha.

Reduced tillage cost (an average of one less for both the spring tillage and layby tillage main

effects) accounted for only $16.28/ha of the increase in net returns, the remainder was due to

increased yield when tillage was eliminated. Reduced tillage can increase net return to the

grower but only if weeds can be managed such that yields are not decreased. In Australia, no-

till sugarcane production has also decreased input costs without adversely affecting crop yield

(Anonymous 1991).

In this research conducted at six locations and on soil types ranging from very fine sandy

loam to silty clay loam, elimination of spring tillage did not hinder the ability to apply

fertilizer when injected using knives or coulters. At the locations where sugarcane was in the

second or third production year crop residue from the previous year’s harvest had

decomposed such that it was not a factor affecting early season sugarcane growth (Richard

1999) or tillage operations. In the study where soil temperature was monitored, elimination of

spring tillage did not hinder warming of beds or emergence and growth of sugarcane.

Furthermore, elimination of all tillage operations (no-till program) did not negatively affect

sugarcane growth or yield and in one study elimination of spring tillage increased sugar yield.

In these studies weed control was excellent throughout the growing season regardless of

tillage or herbicide program. Elimination of spring tillage would prevent mechanical

34

destruction of weeds present on the row shoulders and in row middles and if herbicides are

not effective sugarcane growth and yield could be reduced. Caution should be used in

implementing full season no-till programs where perennial weeds such as bermudagrass

(Cynadon dactylon L. Pers.), johnsongrass (Sorghum halepense L. Pers.), or nutsedge

(Cyperus spp. L.) are problematic.

A reduced tillage program would be a viable option for sugarcane growers in plant cane

and in stubble fields that are not rutted during the previous harvest and when weeds can be

effectively controlled with herbicides. Even though yield increases may not accompany a

reduction in tillage operations in sugarcane, savings in fuel, equipment, and labor costs along

with a possible reduction in soil loss and an increase in soil moisture conservation will make

reduced tillage programs a viable economical option.

LITERATURE CITED

Anonymous. 1991. Minimum tillage. Power farming. Diverse Publishing Co. Pty. ltd. Box370, North Melborne 3051, Australia. 101:32.

Anonymous. 2002. CTIC National Crop Residue Management Survey; ConservationTechnology Information Center: West Lafayette, IN, http://www.ctic.purdue.edu/(accessed February 2004).

Anonymous. 2005. Louisiana Summary Agriculture and Natural Resources 2004.http://www.lsuagcenter.com/agsummary/ (accessed April 2005).

Baker, J.L. and H.P. Johnson. 1983. Evaluating the effectiveness of BMP’s from field studies. in F.W. Schaller and G.W. Baily, eds. Agricultural Management and Water Quality. IowaState University Press, Ames, Iowa.

Blevins, R.L., M.S. Smith, G.W. Thomas and W.W. Frye. 1983. Influence of conservationtillage on soil properties. J. Soil Water Conserv. 38:301-307.

Breaux, J.B. and M.E. Salassi. 2005. Projected Costs and Returns - Sugarcane, LouisianaA.E.A. Information Series No. 229. http://[email protected]/FarmManagement.htm.(accessed March 2005).

35

Carmer, S.G., W.E. Nyquist, and W.M. Walker. 1989. Least significant differences forcombined analyses of esperiments with two- and three- factor treatment designs. Agron. J.81:665-672.

Chen, J.C.P. and C. Chou. 1993. Cane Sugar Handbook. 12th ed. New York: J. Wiley. pp.852-867.

Coats, W. E. and G. Thacker. 1997. Reduced tillage systems for irrigated cotton: Energyrequirements and crop response. App. Engin. Agric. 13(1):31-34.

Dao, T.H. 1993. Tillage and winter wheat residue management effects on water infiltrationand storage. Soil Sci. Soc. Am. J. 57:1586-1595.

Dick, W.A. 1983. Organic carbon, nitrogen and phosphorous concentrations and pH in soilprofiles as affected by tillage intensity. Soil Sci. Soc. Am. J. 47:102-107.

Dick, W.A. and D.M. Van Doren, Jr. 1985. Continuous tillage and rotation combinationeffects on corn, soybean, and oat yield. Agron. J. 77:459-465.

Dick, W.A., E.L. McCoy, W.M. Edwards, and R. Lal. 1991. Continuous application of no-tillto Ohio soils. Agron. J. 83: 65-73.

Doran, J.W. 1980. Soil microbial and biochemical changes associated with reduced tillage.Soil Sci. Soc. Am. J. 44:765-771.

Farahani, H.J., G.A. Peterson, and D.G. Westfall. 1998. Dryland cropping intensification: Afundamental solution to efficient use of precipitation. Adv. Agron. 64:197-223.

Glanville, T.J., G. Titmarsh, M.M. Sallaway, and F. Mason. 1997. Soil erosion in canelandtillage systems. Proc. 1997 conf. Austr. Soc. Sugar Cane Technol. pp. 254-262.

Griffith, D.R., J.V. Mannering, and J.E. Box. 1986. Soil and moisture management withreduced tillage. p. 19-57. In M.A. Sprague and G.B. Triplett, ed. No-tillage and surfacetillage agriculture, the tillage revolution. John Wiley and Sons, New York. p. 19-57.

Guenzi, W.D., Editor. 1974. Pesticides in soil and water. Soil Sci. Soc. Am. Book Ser.,Madison, Wisconsin. 562 pp.

Hager, A. G., L. M. Wax, G. A. Bollero, and E. W. Stoller. 2003. Influence of diphenyletherherbicide application rate and timing on common waterhemp (Amaranthus rudis) controlin soybean (Glycine max). Weed Technol. 17:14–20.

Halvorson, A.D., G.A. Peterson, and C.A. Reule. 2002. Tillage system and crop rotationeffects on dryland crop yield and soil carbon in the central Great Plains. Agron. J. 94:1429-1436.

Hurle, K. and A. Walker. 1980. Persistence and its prediction. in R. J. Hance, ed. Interactionsbetween herbicides and the soil Academic Press, London, England. pp. 83-122.

36

Kennedy, C.W. and R.L. Hutchinson. 2001. Cotton growth and development under differenttillage systems. Crop Sci. 41:1162-1168.

Koskinen, W.C. and C.G. McWhorter. 1986. Weed control in conservation tillage. J. SoilWater Conserv. 41:365-370.

Lal, R., D.J. Eckert, N.R. Fausey, and W.M. Edwards. 1990. Conservation tillage insustainable agriculture. p. 203-225. In C.A. Edwards, eds. Sustainable agricultural systems.Soil and Water Conserv. Soc., Ankeny, IA.

Lamb, J.A., G.A. Peterson, and C.R. Fenster. 1985. Wheat-fallow tillage systems’ effect on a newly cultivated grassland soils’ nitrogen budget. Soil Sci.Soc. Am. J. 49:352 356.

Pear, E., H. Bounza, M. Morales, N. Lopez, S. Hernandez, and I. Martinez. 1992. Influence oftwo soil technologies on the nutrient absorption, radical development and sugarcane yield.Ciencias del Suelo, Riego Y Mechanizacion 2:25-35.

Ricaud, R., and A. Arceneaux. 1986. Some factors affecting ratoon cane longevity inLouisiana. Proc. Int. Soc. Sugar Cane Technol. 19th. Congr. 1:18-24.

Richard, E. P., Jr. 1999. Management of chopper harvester-generated green cane trashblankets: A new concern for Louisiana. Proc. Int. Soc. Sugar Cane Technol. 23(2):52-62.

SAS institute. 2003. SAS User’s Guide: Statistics. Version 8. SAS Institute. Cary, NC. pp.3809.

Saxton, A.M. 1998. A macro for converting mean separation output to letter groupings inProc. Mixed. In Proc. 23rd SAS Users Group Intl., SAS Institute, Cary, NC, pp.1243-1246.Nashville, TN, March 22-25.

Tiessen, H., J.W.B. Stewart, and J.R. Bettany. 1982. Cultivation effects on the amounts andconcentration of carbon, nitrogen, and phosphorous in grassland soils. Agron. J. 74:831-835.

Triplett, G.B. and D.M. Van Doren, Jr. 1977. Agriculture without tillage. Sci. Am. 236:28-33.

Unger, P.W. and L.J. Fulton. 1989. Conventional and no-tillage effects on upper root zonesoil conditions. Soil and Tillage Res. 16:337-344.

Unger, P.W. and D.K. Cassel. 1991. Tillage implement disturbance effects on soil propertiesrelated to soil and water conservation: A literature review. Soil and Tillage Res. 19:363-382.

Vetsch, J.A. and G.W. Randall. 2002. Corn production as affected by tillage system andstarter fertilizer. Agron. J. 94:532-540.

Vyn, T.J., G. Opoku, and C.J. Swanton. 1998. Residue management and minimum tillagesystems for soybeans following wheat. Agron. J. 90:131-138.

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Wagger, M.G. and H.P. Denton. 1992. Crop and tillage rotations: Grain yield, residue coverand soil water. Soil Sci. Soc. Am. J. 56:1233-1237.

Wall, D.A. and E.H. Stobbe. 1984. The effect of tillage on soil temperature and corn (Zeamays L.) growth in Manitoba. Can. J. Plant Sci. 64:59-67.

38

CHAPTER 3

SUGARCANE (SACCHARUM SPP. HYBRIDS) RESIDUE MANAGEMENT ANDREDUCED TILLAGE PROGRAMS

INTRODUCTION

Sugarcane (Saccharum spp. hybrids) is a perennial crop and in Louisiana four to six

harvests are made from a single planting. Although sugarcane is a tropical crop, under

Louisiana growing conditions sugarcane is dormant during the winter and new growth is

initiated usually in March. Throughout the crop cycle sugarcane row shoulders and middles

are tilled to promote crop growth, eliminate ruts, incorporate fertilizer, and control weeds. In

a typical sugarcane production system two to three tillage operations are performed during the

growing season. Although, some form of reduced tillage is used in most agronomic crops,

sugarcane growers have been slow to adopt reduced tillage practices because of concerns over

the negative effect on crop growth and weed control.

At one time the Louisiana sugarcane crop was harvested using soldier harvesters. Whole

stalks were harvested, piled in the field, and burned to remove leaves prior to transporting to

the mill. In the mid 1990’s growers shifted to using combine harvesters where stalks are cut

into billets, loaded directly into wagons, and transported to the mill. Using the combine

harvester, about 80% of the sugarcane in Louisiana is harvested green (without burning first)

and crop residue (tops and leaves) is deposited on the soil surface. When feasible, crop

residue remaining in the field is burned; however, environmental and social concerns related

to burning have encouraged evaluation of alternative residue removal methods. Although the

crop residue can provide suppression of weed competition, there is concern that the residue

may also reduce shoot emergence, early season growth, and yield of the ratoon sugarcane

39

crop (Richard 1999). Ideally it would be desirable to utilize the crop residue in a conservation

tillage program.

Residue cover affects soil temperature and the availability of soil moisture (Beyaert et al.

2002). Reductions in early season corn (Zea Mays L.) growth and, in some cases, grain yield

have been reported and attributed to lower soil temperature under a no-till system (Vyn and

Raimbault 1993). Viator et al. (2005) reported that residue remaining on fields following

harvest of the sugarcane crop decreased soil temperature 2 to 3 ºC in February and March and

increased soil moisture 7 to 8% resulting in delayed emergence of the stubble crop from the

winter dormant period. Azooz et al. (1995) reported that removing residue by cultivation

from a 30-cm wide area over the row at planting of corn (strip tillage) resulted in soil thermal

and moisture conditions similar to a conventional tillage system. Strip tillage also has

enhanced corn emergence (Fortin 1993; Kaspar et al. 1990; Kaspar and Erbach 1998; Swan et

al. 1994; Vetsch and Randall 2000; Wolkowski 2000).

Residue remaining on the soil surface can stabilize soil and a minimum of 20% residue

cover is necessary to reduce soil erosion (Beyaert et al. 2002; Moldenhauer et al. 1983).

Vetsch and Randall (2000) found that residue present in no-till and reduced tillage (zone-till

and strip-till) programs was sufficient to minimize soil erosion. Researchers in Australia

found that incorporating sugarcane residue reduced soil erosion when compared to tillage of

bare soil (Glanville et al. 1997). Distribution of soil carbon and nitrogen in soil under no-till

management is increased because of residue accumulation on the soil surface and enhanced

microbial activity (Doran 1980). In India, sugarcane growth and yield was improved when

residue remained in the field and was attributed to residual nutrients provided from

decomposition of residue as well as a reduced soil bulk density (Srivastava 2003).

40

Fisk et al. (2001) reported that cover crop residue on the soil surface decreased density and

dry weight of perennial weeds 35 and 75%, respectively, and of annual weeds around 80%

when compared with no residue. Winter wheat (Triticum aestivum L.) residue reduced weed

seedling emergence in corn by 45% (Crutchfield et al. 1986) and weed biomass in grain

sorghum (Sorghum bicolor L.) by 60% (Wicks et al. 1994). The level of weed suppression is

directly related to the amount of residue on the soil surface (Crutchfield et al. 1986; Vander

Vorst et al. 1983). Richard (1999) found that sugarcane residue remaining on the soil surface

through the winter period reduced emergence of cool- and warm-season weeds by at least

62%. Although cover crops can reduce weed competition, chemical control measures are still

needed (Curran et al. 1994; Johnson et al. 1993; Yenish et al. 1996).

The objectives of this research were to evaluate the interaction between sugarcane residue

removal (burning or mechanical) and reduced tillage and to evaluate timing of sugarcane

residue removal in respect to weed management and sugarcane growth and yield.

MATERIALS AND METHODS

Residue Management/Tillage Study. Experiments were conducted in 2003 and 2004 on

privately owned farms in St. Gabriel, Youngsville, and Franklin, LA. Cooperators included

Poche Farms, Lanie Farms, and Frank Martin Farms respectively. The experimental design at

each location was a randomized complete block with a three factor factorial treatment

arrangement and four replications. The first factor was residue management (burn,

mechanical removal, or no removal). Crop residue was removed on December 11, 2003, at

St. Gabriel, December 12, 2003, at Youngsville, and January 13, 2004, at Franklin. Crop

residue removal at the three locations was performed within three weeks after ‘LCP 85-384’

sugarcane was harvested using a combine harvester. Information for the three locations

41

concerning soil classification, pH, and organic matter, and crop residue present at the time

removal treatments were imposed is presented in Table 3.1. Crop residue was removed

mechanically with a Sunco Trash Tiger®4. This implement is pulled behind a tractor and is

equipped with concave shaped notched disks (four per row) that rake the residue off the row

top (approximately 76 cm wide) and into the row middles. The second and third factors were

off-bar spring tillage (with or without) and layby tillage (with or without). Off-bar and layby

tillage operations in 2004 were conducted on March 23 and May 25, at St. Gabriel; March 24

and May 27 at Youngsville; and March 16 and May 18 at Franklin.

Crop residue remaining on the soil surface in March just prior to sugarcane emergence was

determined visually as percent ground cover using a scale of 0 to 100% with 0 representing no

soil covered with residue and 100% where the entire soil surface was covered with residue.

Weed ground cover using the same rating scale was also determined in March to evaluate the

effect of sugarcane residue on winter weeds. Weeds were not separated by species but

included spiny sowthistle (Sonchus asper (L.) Hill), annual bluegrass (Poa annua L.), and

Italian ryegrass (Lolium multiflorum Lam.) Sugarcane shoot population was recorded in April

and plant height, measured from the soil surface to the top of the sugarcane canopy, was

recorded in April and June. Sugarcane stalk population and height were also determined in

August. Stalk height was measured from the soil surface to the collar of the youngest leaf on

five randomly selected stalks. Plots were hand harvested in late September and ten randomly

selected stalks were weighed to determine average stalk weight. Sugarcane yield was

calculated using stalk weight data and stalk population data collected in August. Stalk

4 Sunco Industries, 4320 Rodeo Rd., North Platte, NE 69101.

42

Table 3.1. Soil type, classification, pH, percent organic matter, and initial residue dry weight at the three locations used for theresidue management/tillage study in 2004.Variable St. Gabriel, LA Youngsville, LA Franklin, LA

Soil type Commerce silt loam Coteau silt loam Baldwin silt loam

Soil classification fine-silty, mixed, superactive,

nonacid, thermic Fluvaquentic

Endoaquepts

fine-silty, mixed, active,

hyperthermic Glossaquic

Hapludalfs

fine, smectitic, hyperthermic

Chromic Vertic Epiaqualfs

Soil pH 6.9 5.9 6.2

Soil organic matter (%) 2.11 1.32 1.35

Crop residue dry weight (kg/ha) a 13,740 19,420 10,310

a Crop residue was collected between December 11, 2003 and January 13, 2004 within three weeks after ‘LCP 85-384’ sugarcane was harvested with a combine harvester.

43

samples were then crushed and the juice was extracted for analysis of theoretical recoverable

sugar5 using standard methodology (Chen and Chou 1993). Sugar yield was calculated by

multiplying theoretical recoverable sugar by sugarcane yield.

Residue Removal Timing Study. An experiment was conducted in 2003 and 2004 at the

St. Gabriel Research Station, St. Gabriel, LA, in a field of LCP 85-384 sugarcane harvested

with a combine harvester on December 4, 2003. Crop residue on the soil surface on

December 8 when the first removal was initiated, was 6,920 kg/ha dry weight. The soil type

was a Commerce silt loam (fine-silty, mixed, superactive, nonacid, thermic Fluvaquentic

Endoaquept) with 1.01% organic matter and pH of 5.9. The experimental design was a

randomized complete block with a two factor factorial treatment arrangement and four

replications. The first factor was timing of residue removal on December 8, 2003, by burning

and on December 8, 2003, and January 14, February 12, or March 23, 2004 using a Trash

Tiger®. The December burn treatment represents the preferred grower practice. At the March

removal, sugarcane had begun to emerge from the winter dormant period and, therefore, this

treatment represented a worst cane scenario for the effect of residue on sugarcane emergence

and growth. The second factor consisted of spring tillage (with or without) on March 23,

2004.

Winter weed and crop residue ground cover were determined visually in February or

March as described previously. Winter weeds included annual bluegrass (Poa annua L.) and

Italian ryegrass (Lolium multiflorum Lam.) in February and spiny sowthistle (Sonchus asper

(L.) Hill), annual bluegrass (Poa annua L.), and Italian ryegrass in March. Sugarcane shoot

population in April and sugarcane height in April, June, and August were recorded as

5 Sugar content of stalks derived from theoretical recoverable sugar expressed as kilograms of sugar per 1,000 kgof sugarcane.

44

described previously. Plots were harvested in early October using a commercial single row

combine harvester and a weigh wagon fitted with three load cells capable of being tared

between plots to determine sugarcane yield. Before harvesting, samples of 10 randomly

selected stalks were hand harvested and weighed to determine average stalk weight.

Theoretical recoverable sugar analysis was consistent with the previous study. Sugar yield

was calculated by multiplying theoretical recoverable sugar by sugarcane yield.

Data for each study were subjected to the Mixed Procedure in SAS (SAS 2003). Locations,

replications (nested within location), and all interactions containing either of these effects

were considered random effects (Carmer et al.1989). All other dependant variables (residue

management, spring tillage, and layby tillage) were considered fixed effects. Considering

location as an environmental or random effect permits inferences about treatments to be made

over a range of environments (Carmer et al. 1989; Hager et al. 2003). Type III statistics were

used to test the fixed effects. Least square means were used for mean separation at P≤ 0.05.

Letter groupings were converted using the PDMIX800 macro in SAS (Saxton 1998).

RESULTS AND DISCUSSION

Residue Management/Tillage Study. Crop residue at the locations when the study was

initiated ranged from 10,310 to 19,420 kg/ha dry weight (Table 3.1). Data presented

represent an average across three locations. Additionally, there was not a significant

interaction between residue management and tillage program for any of the parameters.

There was, however, a significant effect for some of the variables attributed to residue

management.

Sugarcane residue remaining in March was consistent with residue management practices

imposed after harvest in December or January. When sugarcane residue was removed by

45

burning or mechanically, ground cover of crop residue in March averaged across locations

and tillage programs was no more than 14%, whereas, ground cover was 90% when residue

was not removed (Table 3.2). There was no difference in sugarcane residue ground cover

between the burning and mechanical removal treatments. Winter weed ground cover in

March averaged 14% for the burn treatment and 17% for the mechanical removal treatment

(Table 3.2). This compares with 7% winter weed ground cover where crop residue was not

removed. Even with 90% sugarcane residue on the soil surface, winter weeds were still a

problem and would need to be controlled with a late winter/early spring herbicide treatment.

Other research has shown that although residue on the soil surface can suppress weed

competition (Crutchfield et al. 1986; Vander Vorst et al. 1983), chemical control measures

would still be necessary (Curran et al. 1994; Johnson et al. 1993; Yenish et al. 1996).

Sugarcane height in April (Table 3.3) and sugarcane shoot population in April (Table 3.4)

were reflective only of the residue management and spring tillage treatments because layby

tillage had not been performed. Sugarcane height in April averaged across locations and

tillage programs was equal for the burn and no residue removal treatments and averaged 9.2%

greater than for mechanical removal. Differences among the residue management treatments

in sugarcane shoot population in April were not observed. The reduction in sugarcane height

in April when crop residue was removed mechanically compared with burning was not

detected in height data collected in June or August (Table 3.3). In June, sugarcane height was

equal for the burn and mechanical removal treatments and averaged 10.3 cm taller than for the

no removal treatment. By August, however, there were no differences in sugarcane stalk

46

Table 3.2. Effect of crop residue management and tillage programs on ground cover of sugarcane residue and winter weeds inMarch 2004.

Residue management a

Burn Mechanical removal No removal

Spring tillage/layby tillage b Spring tillage/layby tillage Spring tillage/layby tillage

+/+ +/- -/+ -/- Avg. d +/+ +/- -/+ -/- Avg. +/+ +/- -/+ -/- Avg.

_________________________________________________________ Sugarcane residue ground cover in March (%) _________________________________________________________

13 c 12 13 17 14 b 14 11 9 9 11 b 90 86 92 92 90 a

___________________________________________________________ Winter weed ground cover in March (%) e ___________________________________________________________

13 c 15 14 15 14 a 17 15 20 17 17 a 8 8 8 6 7 b

a At the three (locations St. Gabriel, Youngsville, and Franklin) crop residue was removed between December 11, 2003, andJanuary 13, 2004, by burning or mechanically using a Sunco Trash Tiger® which raked residue from row tops to row middles.Residue removal was performed within three weeks after sugarcane was harvested with a combine harvester.

b Tillage programs consisted of spring tillage (mid to late March) with (+) or without (-) and layby tillage (mid to late May) with(+) or without (-). Specific tillage treatments included +/+ = with spring tillage and with layby tillage (full season conventional);+/- = with spring tillage and without layby tillage; -/+ = without spring tillage and with layby tillage, and; -/- = without springtillage and without layby tillage (full season no-till).

c Data for each parameter represents an average across three locations. A significant residue management by tillage programinteraction was not observed.

d Residue management treatment means for each parameter without letters or followed by the same letter are not significantlydifferent (P≤ 0.05). Letter groupings were converted using the PDMIX800 macro in SAS (Saxton 1998).

e Winter weeds included spiny sowthistle (Sonchus asper (L.) Hill), annual bluegrass (Poa annua L.), and Italian ryegrass(Lolium multiflorum Lam.).

47

Table 3.3. Effect of crop residue management and tillage programs on sugarcane height across the 2004 growing season.Residue management a



+/+ +/- -/+ -/- Avg. d +/+ +/- -/+ -/- Avg. +/+ +/- -/+ -/- Avg.

_____________________________________________________________________________________________________ Sugarcane height in April (cm) _____________________________________________________________________________________________________

34.3 c 34.5 33.0 35.3 34.3 a 31.8 31.2 32.5 32.5 32.0 b 36.6 35.1 35.3 34.8 35.6 a

______________________________________________________________________________________________________ Sugarcane height in June (cm) ______________________________________________________________________________________________________

186.2 184.4 177.5 186.2 183.6 a 181.4 180.8 182.9 182.6 181.9 a 174.5 173.0 172.0 170.7 172.5 b

____________________________________________________________________________________________________ Sugarcane height in August (cm) ____________________________________________________________________________________________________

210.8 210.8 204.0 207.3 208.3 205.2 213.6 205.5 207.8 208.0 205.2 203.7 199.1 200.4 202.2

a At the three locations (St. Gabriel, Youngsville, and Franklin) crop residue was removed between December 11, 2003, andJanuary 13, 2004, by burning or mechanically using a Sunco Trash Tiger® which raked residue from row tops to row middles.Residue removal was performed within three weeks after sugarcane was harvested with a combine harvester.




48

Table 3.4. Effect of crop residue management and tillage programs on sugarcane shoot and stalk population across the 2004growing season.

Residue management a



+/+ +/- -/+ -/- Avg. d +/+ +/- -/+ -/- Avg. +/+ +/- -/+ -/- Avg.

_______________________________________________________________________ Sugarcane shoot population in April (1,000/ha) _______________________________________________________________________

104.4 c 106.7 94.3 99.2 101.1 89.1 102.8 100.1 105.0 99.2 95.7 94.1 95.1 91.9 94.2

_________________________________________________________________________ Sugarcane population in August (1,000/ha) _________________________________________________________________________

122.6 123.2 117.0 122.2 121.2 119.7 126.8 123.7 124.7 123.7 120.5 119.8 121.4 121.7 120.8

a At the three locations (St. Gabriel, Youngsville, and Franklin) crop residue was removed between December 11, 2003, andJanuary 13, 2004, by burning or mechanically using a Sunco Trash Tiger® which raked residue from row tops to row middles.Residue removal was performed within three weeks after sugarcane was harvested with a combine harvester.




49

height among the residue management treatments. Additionally, sugarcane stalk population

in August was equivalent regardless of residue management treatment (Table 3.4). When

differences in sugarcane stalk population and height among residue management treatments

are not observed in August it would be expected that sugarcane yield also would not be

affected, which was the case in this study (Table 3.5). However, sugar content of stalks

would affect sugar yield. Sugar yield averaged across locations and tillage programs was

equal for the burn and mechanical residue removal treatments (8,470 kg/ha) and averaged

8.6% greater than when residue was not removed (7,800 kg/ha).

Economic analysis was not conducted for this study. However, mechanical removal of

residue would cost considerably more than burning, although there would be some cost

associated with burning. This study shows that to maximize sugar yield, the residue from the

previous crop should be removed either by burning or mechanically. In this study, crop

residue was removed in December or January within 3 weeks after harvest. Results also show

that elimination of spring tillage and layby tillage did not hinder sugarcane growth or yield

when compared with a full season tillage program. These findings are supported by previous

research (Judice et al. 2005). Of interest in the present study is that neither tillage nor

fertilizer application was negatively affected when the Trash Tiger® was used and sugarcane

residue from the row top was placed into the row middles. When using the Trash Tiger®

some soil from the row top would be moved along with the crop residue. Although not

measured in this study it was felt that mixing of soil with residue may have enhanced

decomposition (Stinner et al. 1984).

Residue Removal Timing Study. The winter weed and sugarcane ground cover data

were collected before the March removal timing and before plots were tilled. Therefore, the

50

Table 3.5. Effect of crop residue management and tillage programs on sugarcane yield and sugar yield.Residue management a



+/+ +/- -/+ -/- Avg. d +/+ +/- -/+ -/- Avg. +/+ +/- -/+ -/- Avg.

___________________________________________________________________________________ Sugarcane yield (1,000 kg/ha) ___________________________________________________________________________________

80.9 c 82.7 74.0 77.1 78.7 75.6 81.4 80.5 78.7 78.9 77.3 74.0 75.6 72.9 74.9

__________________________________________________________________________________________ Sugar yield (kg/ha) ________________________________________________________________________________________

8,640 8,920 7,960 8,280 8,450 a 8,060 8,710 8,580 8,610 8,490 a 8,030 7,630 7,980 7,570 7,800 b

a At the three locations (St. Gabriel, Youngsville, and Franklin)crop residue was removed between December 11, 2003, andJanuary 13, 2004, by burning or mechanically using a Sunco Trash Tiger® which raked residue from row tops to row middles.Residue removal was performed within three weeks after sugarcane was harvested with a combine harvester.




51

mechanical March removal treatment would represent a no removal control. Results showed

that sugarcane residue can suppress weed emergence and growth. Winter weed ground cover

in February was 6% where crop residue was burned or removed mechanically in December

(Table 3.6). When residue had not been removed winter weed ground cover was 2%. In early

March, winter weed ground cover was 5% when crop residue had not been removed, but was

10 and 18% when crop residue was burned or removed mechanically, respectively, in

December (Table 3.6). The greater winter weed ground cover when sugarcane residue was

removed mechanically versus where it was removed by burning could be due to the slight

stirring of the soil with the Trash Tiger,® which may have stimulated weed seed germination.

Results showed that even though the crop residue provided some suppression of weeds, weeds

were still present and would need to be controlled to eliminate early season competition with

sugarcane as it emerges for the winter dormant period. Of equal concern is the amount of

crop residue on the soil surface in early March and how it might impact sugarcane emergence

and growth. Crop residue ground cover in early March was 74% when residue had not been

removed and had remained on the soil surface since harvest in early December (Table 3.6).

This is in contrast to 7 to 12% crop residue ground cover when residue was either burned in

December or removed mechanically in December, January, or February. An attempt to

quantify the amount of residue on the soil surface was not made. However, research by Selim

et al. (2004) has shown that with LCP 85-384 over the three year crop cycle half life for crop

residue decay ranged from 126 to 171 days.

For sugarcane height, population, and sugarcane and sugar yield a significant interaction

between residue removal timing and spring tillage was not observed. There was, however, a

52

Table 3.6. Effect of residue removal timing on ground cover of winter weeds and cropresidue.

Winter weeds Crop residue

Residue removal timing a 2/20/04 b 3/3/04 c 3/3/04

______________ Ground cover (%) ______________

Burn December 6 a f 10 b 8 b

Mechanical December d 6 a 18 a 7 b

Mechanical January 3 b 4 c 8 b

Mechanical February 2 b 4 c 12 b

Mechanical March e 2 b 5 c 74 a

a Crop residue removed December 8, 2003, January 14, 2004, February 12, 2004, or March23, 2004. Residue was deposited on the soil surface when sugarcane was harvested with acombine harvester December 4, 2003.

b Winter weeds included annual bluegrass (Poa annua L.) and Italian ryegrass (Loliummultiflorum Lam.).

c Winter weeds included spiny sowthistle (Sonchus asper (L.) Hill), annual bluegrass (Poaannua L.), and Italian ryegrass (Lolium multiflorum Lam.).

d Crop residue removed mechanically using the Sunco Trash Tiger® which rakedresiduefrom row tops to row middles.

e Residue had not been removed when data were collected.f Means within a column followed by the same letter are not significantly different (P≤

0.05). Letter groupings were converted using the PDMIX800 macro in SAS (Saxton 1998).

53

significant main effect for some of the variables attributed to timing of residue removal.

Sugarcane height in April and in June averaged across spring tillage was equal when crop

residue was removed in December by burning or mechanically (Table 3.7). Delaying

mechanical removal until January resulted in sugarcane height in April and June equal to that

of the March mechanical removal. Sugarcane height in August was equivalent when residue

was removed in December and in January either by burning or mechanically (Table 3.7).

Sugarcane height for these treatments averaged 7.4% more than when residue was removed in

March. There was no significant difference in sugarcane height in August between the

February and March mechanical removal treatments. Sugarcane shoot population in April

averaged across spring tillage was equivalent when residue was removed in December,

January, or February, but stalk population was reduced an average of 14.8% when residue

removal was delayed until March (Table 3.8).

Averaged across spring tillage, sugarcane yield was greater when residue was removed by

burning in December than when removed mechanically in February or March (Table 3.9).

Yields did not differ for the December burn compared with mechanical removal of crop

residue in December or January. Sugar yield averaged across spring tillage was equivalent

when crop residue was removed in December by burning or mechanically and averaged 8,670

kg/ha. Compared with December residue removal, delaying mechanical removal of residue

until February or March decreased yields an average of around 13%. Richard (1999) reported

early season growth reduction and reduced yield when residue from the previous sugarcane

crop was not removed. It is likely that yield reduction observed in this research is related to

increased moisture and decreased temperature early in the growing season when residue was

not removed from the row top (Viator et al. 2005).

54

Table 3.7. Effect of residue removal timing and spring tillage on sugarcane height across the 2004 growing season.April June August

Spring tillage b Spring tillage Spring tillage

Residue removal timing a + - Avg. c + - Avg. + - Avg.

____________________________________________________ Sugarcane height (cm) ____________________________________________________

Burn December 33.8 36.8 35.3 a e 172.2 165.1 168.7 a 204.5 197.6 200.9 a

Mechanical December d 34.3 34.3 34.3 ab 163.8 162.1 162.8 ab 199.4 191.8 195.6 ab

Mechanical January 31.8 31.2 31.5 c 159.5 155.7 157.5 bc 197.6 192.5 195.1 ab

Mechanical February 35.6 35.1 35.3 a 146.1 155.7 150.9 c 187.5 192.5 190.0 bc

Mechanical March 31.2 33.8 32.5 bc 153.2 146.1 149.6 c 186.2 181.1 183.6 c

a Crop residue removed December 8, 2003, January 14, 2004, February 12, 2004, or March 23, 2004. Residue was deposited onthe soil surface when sugarcane was harvested with a combine harvester December 4, 2003.

b Spring tillage with (+) or without (-) was conducted on March 23, 2004. A significant residue removal timing by spring tillageinteraction was not observed for any of the parameters.

c Averaged across spring tillage treatments (+ and -).d Crop residue removed mechanically using the Sunco Trash Tiger® which raked residue from row tops to row middles.e Means within a column followed by the same letter are not significantly different (P≤ 0.05). Letter groupings were converted


55

Table 3.8. Effect of residue removal timing and spring tillage on sugarcane shoot populationin April 2004.

Sugarcane shoot population

Spring tillage b

Residue removal timing a + - Avg. c

__________________ 1,000/ha __________________

Burn December 129.5 114.3 121.9 a e

Mechanical December d 120.0 121.1 120.7 a

Mechanical January 110.7 125.6 118.1 a

Mechanical February 122.0 113.0 117.5 a

Mechanical March 102.0 101.5 101.8 b

a Crop residue removed December 8, 2003, January 14, 2004, February 12, 2004, or March23, 2004. Residue was deposited on the soil surface when sugarcane was harvested with acombine harvester December 4, 2003.

b Spring tillage with (+) or without (-) was conducted on March 23, 2004. A significantresidue removal timing by spring tillage interaction was not observed.

c Averaged across spring tillage treatments (+ and -).d Crop residue removed mechanically using the Sunco Trash Tiger® which raked residue

from row tops to row middles.e Means within a column followed by the same letter are not significantly different (P≤

0.05). Letter groupings were converted using the PDMIX800 macro in SAS (Saxton 1998).

56

Table 3.9. Effect of residue removal timing and spring tillage on sugarcane and sugar yield in 2004.Sugarcane yield Sugar yield

Spring tillage b Spring tillage

Residue removal timing a + - Avg. c + - Avg.

___________ 1,000 kg/ha ___________ ___________________ kg/ha ___________________

Burn December 76.9 69.1 74.0 a e 9,030 8,450 8,730 a

Mechanical December d 76.0 74.4 73.1 ab 9,070 8,150 8,610 ab

Mechanical January 72.0 71.1 71.5 abc 8,000 7,990 7,990 bc

Mechanical February 66.6 64.6 67.3 bc 7,450 7,573 7,560 c

Mechanical March 68.6 66.1 65.5 c 7,820 8,290 7,500 c

a Crop residue removed December 8, 2003, January 14, 2004, February 12, 2004, or March 23, 2004. Residue was deposited onthe soil surface when sugarcane was harvested with a combine harvester December 4, 2003.

b Spring tillage with (+) or without (-) was conducted on March 23, 2004. A significant residue removal timing by spring tillageinteraction was not observed for any of the parameters.

c Averaged across spring tillage treatments (+ and -).d Crop residue removed mechanically using the Sunco Trash Tiger® which raked residue from row tops to row middles.e Means within a column followed by the same letter are not significantly different (P≤ 0.05). Letter groupings were converted


57

Research showed that sugarcane crop residue should be removed to maximize yield of the

ratoon crop. Preferably crop residue should be removed as soon after harvest as possible and

before the end of December. When sugarcane is not harvested until January residue should be

removed immediately after harvest. Results also showed that a reduced tillage program can

be successful both when crop residue is removed by burning or by mechanical means. The

Trash Tiger® did an excellent job of removing residue from the top of the sugarcane rows but

residue in the row middles was essentially doubled. As also noted in the previous study when

residue was removed mechanically, the normal spring off-bar tillage operation and fertilizer

application were not hindered. Mechanical removal of the crop residue in combination with a

reduced tillage program can decrease cost of production by eliminating tillage operations

without sacrificing yield and can help to reduce soil loss.

LITERATURE CITED

Azooz, R. H., B. Lowery, and T. C. Daniel. 1995. Tillage and residue management influenceon corn growth. Soil and Tillage Res. 33:215-227.

Beyaert, R. P., J. W. Schott, and P.H. White. 2002. Tillage effect on corn (Zea mays L.)production in a coarse-textured soil in southern Ontario. Agron. J. 94:767-774.

Carmer, S. G., W. E. Nyquist, and W. M. Walker. 1989. Least significant differences forcombined analyses of experiments with two- and three- factor treatment designs. Agron. J.81:665-672

Chen, J.C.P. and C. Chou. 1993. Cane Sugar Handbook. 12th ed. New York: J. Wiley. Pp.852-867.

Crutchfield, D. A., G. A. Wicks, and O. C. Burnside. 1986. Effect of winter wheat (Triticumaestivum L.) straw mulch level on weed control. Weed Sci. 34:110-114.

Curran, W. S., L. D. Hoffman, and E. L. Werner. 1994. The influence of a hairy vetch (Viciavillosa Roth.) cover crop on weed control and corn (Zea may L.) growth and yield. WeedTechnol. 8:777-784.

Doran, J. W. 1980. Soil microbial and biochemical changes associated with reduced tillage.Soil Sci. Soc. Am. J. 44:765-771.

58

Fisk, J. W., O. B. Hesterman, A. Shrestha, J. J. Kells, R. R. Harwood, J. M. Squire, and C. C.Sheaffer. 2001. Weed suppression by annual legume cover crops in no-till corn. Agron. J.93:319-235.

Fortin, M. C. 1993. Soil temperature, soil water, and no-till corn development following in-row residue removal. Agron. J. 85:571-576.

Glanville, T. J., G. Titmarsh, M. M. Sallaway, and F. Mason. 1997. Soil erosion in canelandtillage systems. Proc. Aust. Soc. Sugar Cane Technol. April 29-May, 1997 pp. 254-262.

Hager, A. G., L. M. Wax, G. A. Bollero, and E. W. Stoller. 2003. Influence of diphenyletherherbicide application rate and timing on common waterhemp (Amaranthus rudis) controlin soybean (Glycine max). Weed Technol. 17 14–20.

Johnson, G. A., M. S. Defelice, and Z. R. Helsel. 1993. Cover crop management and weedcontrol in corn (Zea mays). Weed Technol. 7:425-430.

Judice, W.E., J.L. Griffin, C. A. Jones, and L. M. Etheredge. 2005. Weed management inreduced tillage sugarcane. Proc. South. Weed. Sci. Soc. 58:(In Press).

Kasper, T. C., D. C. Erbach, and R. M. Cruse. 1990. Corn response to seed-row residueremoval. Soil Sci. Soc. of Am. J. 54:1112-1117.

Kaspar, T. C. and D. C. Erbach. 1998. Improving stand establishment in no-till with residue-clearing planter attachments. Trans. ASAE 41:301-306.

Moldenhauer, W. C., G. W. Langdale, W. Frye, D. K. McCool, R. I. Papendick, D. E. Smika,and D. W. Fryrear. 1983. Conservation tillage for erosion control. J. Soil Water Conserv.38:144-151.

Richard, E. P., Jr. 1999. Management of combine harvester-generated green cane trashblankets: A new concern for Louisiana. Proc. Int. Soc. Sugarcane Technol. 23(2):52-62.

SAS institute. 2003. SAS User’s Guide: Statistics. Version 8. SAS Institute. Cary, NC. pp.3809.

Saxton, A. M. 1998. A macro for converting mean separation output to letter groupings inProc Mixed. In Proc. 23rd SAS Users Group Intl., SAS Institute, Cary, NC, pp1243-1246.Nashville, TN, March 22-25.

Selim, H. M., B. J. Naquin, R. L. Bengston, H. Zhu, J. L. Griffin, and L. Zhou. 2004.Herbicide retention and runoff losses as affected by sugarcane mulch residue. Louis. Agric.Exp. Stn. Bull. 883. 43 pp.

Srivastava, A. C. 2003. Energy savings through reduced tillage and trash mulching inSugarcane production. App. Eng. Agric. 19(1):13-18.

59

Stinner, B. R., D. A. Crossley, Jr., E. P. Odum, and R. L. Todd. 1984. Nutrient budgets andinternal cycling of N,P,K, Ca, and Mg in conventional tillage, no-tillage, and old-fieldecosystems in the Georgia piedmont. Ecology. 65(2):354-369.

Swan, J. B., R. L. Higgs, T. B. Bailey, N. C. Wollwenhaupt, W. H. Paulson, and A. E.Peterson. 1994. Surface residue and in-row treatment effects on long-term no tillagecontinuous corn. Agron. J. 86:759-766.

Teasdale, J. R. 1996. Contributions of cover crops to weed management in sustainableagriculture systems. Prod. Agric. 9:475-479.

Vander Vorst, P. B., G. A. Wicks, and O. C. Burnside. 1983. Weed control in a winter wheat-corn-ecofarming rotation. Agron. J. 75:507-511.

Vetsch, J. A. and G. W. Randall. 2000. Enhancing no-tillage systems for corn with starterfertilizers, row cleaners, and nitrogen placement method. Agron. J. 92:309-315.

Viator, R. P., R. M. Johnson, E. P. Richard, Jr. 2005. Management of the post-harvest residueblanket. Sugar Bull. 83(5):11-12.

Vyn, T. J. and B. A. Raimbault. 1993. Long-term effect of five tillage systems on cornresponse and soil structure. Agron. J. 85:1074-1079.

Wicks, G. A., P. T. Nordquist, G. E. Hanson, and J. W. Schmidt. 1994. Influence of winterwheat (Triticum aestivum L.) cultivars on weed control in sorghum (Sorghum bicolor).Weed Sci. 42:27-34.

Wolkowski, R. P. 2000. Row-placed fertilizer for maize grown with an in-row crop residuemanagement system in southern Wisconsin. Soil and Tillage. Res. 54:55-62.

Yenish, J. P., A. D. Worsham, and A. C York. 1996. Cover crops for herbicide replacement inno-tillage corn (Zea mays L.). Weed Technol. 10:815-821.

60

CHAPTER 4

SUMMARY

Although sugarcane is a tropical crop, under Louisiana conditions sugarcane remains

dormant during the winter and new growth is initiated usually in March. Throughout the crop

cycle sugarcane row shoulders and middles are tilled to promote crop growth, eliminate ruts,

incorporate fertilizer, and control weeds. Typically three tillage operations are performed

during the growing season. The shift in recent years in Louisiana to use of combine

harvesters that harvest sugarcane green and deposit residue on the soil surface has presented

new challenges in how best to manage crop residue. Research was conducted from 2002 to

2004 to assess the potential of reduced tillage programs in sugarcane. The effect of tillage

programs on weed management, sugarcane growth and yield, and economics were

investigated. Additionally, alternative means to manage crop residue and how the residue

might impact reduced tillage programs were evaluated.

In the first tillage study conducted over two years residue from the previous crop was not

present. Tillage treatments included off-bar spring tillage in late March (with or without) and

layby tillage in mid-May (with or without). There were no differences in sugarcane height in

April or May or in sugarcane shoot population in April for the various tillage programs

whether hexazinone plus diuron was applied in March on a band or as a broadcast treatment.

The fact that early season sugarcane emergence and growth were not hindered when spring

off-bar tillage was eliminated indicates that spring tillage was not needed. Weed control was

excellent when hexaxinone plus diuron was used and weeds were not a limiting factor in this

study. Differences among the tillage treatments and herbicide treatments for sugarcane

growth parameters and for sugarcane yield and sugar yield were not observed, clearly

61

showing that a no-till program (without spring and layby tillage) was as effective as a

conventional tillage program (with spring and layby tillage). Economic analysis showed that

eliminating tillage will increase net return when hexazinone plus diuron is banded, if yield is

not affected. However, if herbicide must be applied broadcast to control weeds then any

savings due to reduced tillage would be offset by increased herbicide cost.

In a second study tillage treatments were the same as included in the first study and

experiments were conducted in 2004 at five locations. In addition, a late March broadcast

application of pendimethalin plus metribuzin was compared with hexazinone plus diuron.

Weed control was excellent regardless of herbicide program used. A significant interaction

between spring tillage and layby tillage programs was not observed for sugarcane height,

sugarcane shoot/stalk population, or sugarcane and sugar yield. There was, however, a

significant main effect of spring tillage on stalk population in August and a significant main

effect of spring and layby tillage on sugar yield. Sugarcane stalk population in August as well

as sugar yield were increased when either spring tillage or layby tillage were eliminated. The

lower sugarcane stalk population in August and sugar yield associated with tillage could be

attributed to stress due to root pruning and drying of the soil. Rainfall in 2004 was a limiting

factor to sugarcane growth especially during the later part of the growing season.

Reduced tillage programs can increase net return to the grower but only if weeds can be

managed such that yields are not decreased. At six locations where the tillage research was

conducted soil types ranged from very fine sandy loam to silty clay loam and elimination of

spring tillage did not hinder the ability to apply fertilizer when injected using knives or

coulters. It should be noted that in these studies residue from the previous crop was not a

factor affecting sugarcane growth or tillage operations. When soil temperature was monitored

62

at a 5 cm depth within the non cultivated sugarcane drill early in the growing season,

elimination of spring tillage did not slow warming of beds or emergence and growth of

sugarcane. Furthermore, elimination of all tillage operations (no-till program) did not

negatively affect sugarcane growth or yield and in one study elimination of spring tillage

increased sugar yield. In both tillage studies, weed control was excellent throughout the

growing season regardless of tillage or herbicide program. Elimination of spring tillage

would prevent mechanical destruction of weeds present on the row shoulders and middles and

if herbicides are not effective sugarcane growth and yield could be reduced. Caution should

be used in implementing full season no-till programs where perennial weeds such as

bermudagrass (Cynodon dactylon L. Pers.), johnsongrass (Sorghum halepense L.), or

nutsedge (Cyperus spp. L.) are problematic.

Since crop residue was not an issue in the previous studies, research was conducted in

2004 at three locations to evaluate the possible interaction between tillage programs (no-till,

conventional tillage, and reduced tillage) and sugarcane residue management (burn,

mechanical, or no removal). Mechanical removal was accomplished using a Sunco Trash

Tiger®. This implement is tractor pulled and equipped with concave-shaped notched disks

(four per row) that rake the residue off the row top and into the row middle. In respect to

weed control, sugarcane growth, and sugarcane and sugar yield a significant interaction

between tillage program and residue management was not detected. There was, however, a

significant effect for some of the variables attributed to residue management. Even with 90%

sugarcane residue on the soil surface, winter weeds were still a problem and would need to be

removed with a late winter/early spring herbicide treatment. Sugar yield averaged across

locations and tillage programs was equal for the burn and mechanical residue removal

63

treatments and averaged 8.6% greater than where residue was not removed (8,470 kg/ha vs.

7,800 kg/ha).

Although economic analysis was not conducted for this study, mechanical removal of

residue would cost considerably more than burning. To maximize sugar yield the residue

from the previous crop should be removed either by burning or by mechanical removal. In

this study crop residue was removed in December or January within three weeks after harvest.

Elimination of spring tillage and layby tillage did not hinder sugarcane growth or yield when

compared with a full season tillage program. Neither tillage nor fertilizer application was

negatively affected when the Trash Tiger® was used to mechanically remove crop residue

from the row top.

The residue management tillage research was expanded in 2004 to not only compare crop

residue removal by burning and with the Trash Tiger® (mechanical removal) in December,

but to also evaluate removal of crop residue with the Trash Tiger® in January, February, and

March. Additionally, superimposed on the residue management treatments was off-bar tillage

in March (with or without).

Winter weed ground cover was greater where sugarcane residue was removed

mechanically versus burning and could be due to the slight stirring of the soil on the row top

with the Trash Tiger®. Even though crop residue provided some suppression of weeds, weeds

were still present and would need to be controlled to eliminate early season competition with

sugarcane as it emerges from the winter dormant period. For sugarcane height, population,

and yield a significant interaction between residue removal timing and spring tillage was not

observed. Sugarcane height in April and in June averaged across spring tillage was equal

when crop residue was removed in December by burning or by mechanical removal.

64

Delaying mechanical removal until January resulted in sugarcane height in April and June

equal to that of the March mechanical removal. Sugarcane height in August was equivalent

when residue was removed in December or in January either by burning or mechanical and

there was no difference between the February and March mechanical removal treatments.

Sugarcane shoot population in April averaged across spring tillage was equivalent when

residue was removed in December, January, or February but population was reduced when

residue removal was delayed until March.

Averaged across spring tillage, sugarcane yield was greater when residue was removed by

burning in December than when removed mechanically in February or March. Yields did not

differ for the December burn compared with mechanical removal of crop residue in December

or January. Sugar yield averaged across spring tillage was equivalent when crop residue was

burned in December or removed mechanically. Compared with residue removal in

December, delaying mechanical removal of residue until February or March decreased yields

an average of around 13%.

Research showed that sugarcane crop residue remaining on the soil surface after harvest

should be removed to maximize yield of the ratoon crop. Preferably, crop residue should be

removed as soon as possible after harvest and before the end of December. If sugarcane

harvest is delayed until January, crop residue should be removed immediately after harvest.

Results also show that a reduced tillage program can be successful both when crop residue is

removed by burning or by mechanical means. The Trash Tiger® did an excellent job of

removing residue from the top of the sugarcane rows but residue in the row middles was

essentially doubled. As also noted previously when residue was removed mechanically, the

normal spring off-bar tillage operations and the fertilizer application were not hindered.

65

A reduced tillage program would be a viable option for sugarcane growers in plant cane

and in stubble fields when weeds can be controlled and in stubble fields not rutted during the

previous harvest and when residue from the previous crop can be managed. Timely

mechanical removal of crop residue with the Trash Tiger® can be as effective as burning.

Even though yield increases may not accompany a reduction in tillage operations in

sugarcane, savings in fuel, equipment, and labor costs along with a possible reduction in soil

loss and an increase in soil moisture conservation will make reduced tillage programs a viable

economical option.

66

APPENDIX: THREE WAY INTERACTION MEANS FOR TILLAGE STUDY 2

Table A.1. Three way interaction means for Tillage Study 2. Effect of spring herbicideprograms and tillage programs on sugarcane height throughout the growing season.


Pendamethalin + metribuzin Hexazinone + diuron


+/+ +/- -/+ -/- +/+ +/- -/+ -/-

___________________________________ Sugarcane height in April (cm) ____________________________________

42.4 c 37.8 39.9 40.4 38.9 38.1 38.1 41.7

___________________________________ Sugarcane height in June (cm) ____________________________________

174.8 180.1 178.3 180.8 177.5 176.0 178.6 178.8

__________________________________ Sugarcane height in August (cm) ___________________________________

200.2 200.4 204.0 203.2 198.6 197.9 199.6 200.2

a Herbicide treatments include pendimethalin at 2.77 kg ai/ha plus metribuzin at 1.26 kgai/ha or a premix of hexazinone at 0.59 kg ai/ha plus diuron at 2.10 kg ai/ha applied in lateMarch.


c Data for each parameter averaged across five locations (Assumption, Iberia, St. James, St.Martin, and St. Mary parishes) for the 2004 growing season. For each parameter interactionsbetween herbicide and tillage programs were not observed (P≤ 0.05).

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Table A.2. Three way interaction means for Tillage Study 2. Effect of spring herbicideprograms and tillage programs on sugarcane shoot and stalk population across the growingseason.




+/+ +/- -/+ -/- +/+ +/- -/+ -/-

_________________________ Sugarcane shoot population in April (1,000/ha) __________________________

130.2 c 136.5 139.7 146.4 153.3 129.0 135.1 139.7

_________________________ Sugarcane stalk population in August (1,000/ha) _________________________

111.8 116.7 124.9 124.9 110.9 110.2 125.0 114.7

a Herbicide treatments include of pendimethalin at 2.77 kg ai/ha plus metribuzin at 1.26 kgai/ha or a premix of hexazinone at 0.59 kg ai/ha plus diuron at 2.10 kg ai/ha applied in lateMarch.



68

Table A.3. Three way interaction means for Tillage Study 2. Effect of spring herbicideprograms and tillage programs on sugarcane yield and sugar yield.




+/+ +/- -/+ -/- +/+ +/- -/+ -/-

____________________________________ Sugarcane yield (1,000 kg/ha) ____________________________________

70.2 c 78.5 76.2 84.5 65.5 72.0 74.9 70.4

__________________________________________ Sugar yield (kg/ha) __________________________________________

7,060 7,940 7,640 8,830 6,510 7,400 7,780 7,160

a Herbicide treatments include of pendimethalin at 2.77 kg ai/ha plus metribuzin at 1.26 kgai/ha or a premix of hexazinone at 0.59 kg ai/ha plus diuron at 2.10 kg ai/ha applied in lateMarch.



69

VITA

Wilson Elie Judice is the youngest son of Carolyn and Robert Judice. Born on

February 14, 1980, he grew up in Franklin, Louisiana, and attended Hanson Memorial High

School. Wilson graduated from Louisiana State University with a Bachelor of Science degree

in plant and soil systems - agronomy in May 2003. He enrolled in the Department of

Agronomy and Environmental Management graduate program under the direction of Dr. Jim

Griffin in 2003 and is currently a candidate for the degree of Master of Science in agronomy

with an educational and research emphasis in weed science. Following graduation, Wilson

will return to the family farm in Franklin, Louisiana.

reduced tillage and residue management programs in

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