water use and onion crop production in no-tillage and conventional

7/28/2019 Water Use and Onion Crop Production in No-tillage and Conventional

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19Hortic. bras., v. 28, n. 1, jan.- mar. 2010

The onion (Allium cepa L.) is thethird vegetable crop of economicalimportance in Brazil with a totalharvested area of 62,750 hectares anda total production of 1.3 million tons(Embrapa Hortalias, 2008). Generally

speaking, the use of conventional tillagesystem (CT) for onion productionpredominates in Brazil, however, due toits benets the no-tillage system (NT) has

been adopted in some production areasof Brazil, mainly, in Santa Catarina, SoPaulo, Minas Gerais and Gois States(Madeira & Oliveira, 2005).

According to Gilley et al. (1990) andDerpsch et al. (1991), the advantages ofNT include reduced machinery trafc,

soil structure improvement, increasinginfiltration and soil-water retention,

MAROUELLI WA; ABDALLA RP; MADEIRA NR; SILVA HR; OLIVEIRA AS. 2010. Water use and onion crop production in no-tillage and conventionalcropping systems.Horticultura Brasileira28: 19-22.

Water use and onion crop production in no-tillage and conventional

cropping systems

Waldir Aparecido Marouelli1; Rmulo P Abdalla2; Nuno R Madeira1; Henoque R da Silva1; Aureo S de

Oliveira31Embrapa Hortalias, C. Postal 218, 70351-970 Braslia-DF; 2Faculdade da Terra de Braslia, Quadra 203, rea Especial, Lote 32, 72610-300 Recanto das Emas-DF; 3Universidade Federal do Recncavo da Bahia - Ncleo de Engenharia de gua e Solo, C. Postal 28, 44380-000 Cruz das Almas-BA; [email protected]; [email protected]; [email protected]; [email protected];[email protected]

ABSTRACT

The objective of the present study was to evaluate the effects ofcrop residue covers (0.0; 4.5; 9.0; 13.5 t ha -1 millet dry matter) onwater use and production of onion cultivated in no-tillage plantingsystem (NT) as compared to conventional tillage system (CT). Thestudy was carried out at Embrapa Hortalias, Brazil, under the typicalSavanna biome. Irrigations were performed using a sprinkle irrigationsystem when soil-water tension reached between 25 and 30 kPa. Theexperimental design was randomized blocks with three replications.Total net water depth applied to NT treatment was 19% smaller thanthe CT treatment, however, water savings increased to 30% for therst 30 days following seedlings transplant. Crop biomass, bulb size

and yield, and rate of rotten bulbs were not signicantly affected

by treatments. The water productivity index increased linearly withincreasing crop residue in NT conditions. Water productivity indexof NT treatments with crop residue was on average 30% higher thanthat in the CT system (8.13 kg m-3).

Keywords:Allium cepa L., reduced tillage, water use efciency,irrigation, Savannah.

RESUMO

Uso de gua e produo de cebola em sistemas de plantio

direto e convencional

O objetivo do presente estudo foi avaliar o efeito do nvel depalhada no solo (0,0; 4,5; 9,0; 13,5 t ha-1 de matria seca de milheto)em sistema de plantio direto (PD) sobre o uso de gua e produo decebola, tendo como controle o sistema de plantio convencional (PC).

O ensaio foi conduzido na Embrapa Hortalias, em regio tpica dobioma Cerrado. As irrigaes foram realizadas por asperso a todo omomento que a tenso de gua no solo atingiu entre 25 e 30 kPa. Odelineamento experimental foi blocos ao acaso com trs repeties.A lmina de gua aplicada em PD foi de at 19% menor que no trata-mento PC durante o ciclo da cultura, sendo que durante os primeiros30 dias do ciclo aps o transplante das mudas a economia chegou a30%. O desenvolvimento de plantas, o tamanho e o rendimento de

bulbos, e a taxa de bulbos podres no foram afetados signicativa-mente pelos tratamentos. O ndice de produtividade da gua no PDaumentou linearmente com o aumento do nvel de palhada, sendo queo ndice nos tratamentos PD com palhada foi em mdia 30% maiorque em PC (8,13 kg m-3).

Palavras-chave:Allium cepa L., cultivo mnimo, ecincia do uso

de gua, irrigao, Cerrado.

(Recebido para publicao em 23 de outubro de 2008; aceito em 11 de fevereiro de 2010)

(Received on October 23, 2008; accepted on February 11, 2010)

water loss reduction by evaporationand runoff, superior crop root systemdevelopment, improved control ofweeds, erosion processes reduction, andincreased water use efciency.

Field research on the use of NT

systems for vegetable production isscarce and management practices thatinclude irrigation frequency and amountof applied water are, in general, the sameas recommended for CT. As a result ofthe inadequate crop water managementit is common to notice higher intensityof diseases in NT which reduces cropyield and harvest quality affecting farmrevenue reducing loss of the knownbenefits obtained with this plantingsystem.

Water conservation with the NT

systems mainly occurs due to the cropresidues left on soil surface whichact as a physical barrier against waterevaporation (Derpsch et al., 1991).

During the early development stage,onion plants only cover a fractionof the soil surface, therefore, soilevaporation accounts for most of thecrop evapotranspiration. Then, plantwater use during this stage is less mainlyfor crops with lower capability of soilcoverage (Stone & Moreira, 2000).On the other hand, the transpirationprocess becomes predominant as plantsgrow and cover larger fractions ofsoil surface. According to Allen et al.(1998), crop evapotranspiration canbe reduced in as much as 25% duringthe early stage and between 5 and 10%


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20 Hortic. bras., v. 28, n. 1, jan.- mar. 2010

during the maximum development stagefor a condition of 50% of surface soilcoverage with crop residues. Landers(1995) reported water conservation inNT varying between 10 and 20% inoxysols of the Central Brazil.

The objective of the present studywas to quantify both irrigation water useand production of onion when cultivatedin NT systems with different levels ofcrop residue covers as compared to CT,in a typical condition of climate and soilin the Brazilian Savannahs.

MATERIAL AND METHODS

Field plots were set up in the EmbrapaHortalias experimental station,Braslia, Brazil, during the dry season

of 2007 in the area for the managementof NT. The soil was a typical dystrophicRed Oxysol of Savannah with claytexture and water retention of 1.2 mmcm-1 (Embrapa, 2006). According to theKppen classication, the climate is a

Cwa, i.e., temperate humid with drywinter and hot summer.

The experimental design wasrandomized blocks with ve treatments

and three replications. The treatmentsconsisted of four rates of millet crop

residue covering the soil (0.0; 4.5; 9.0;13.5 t ha-1 of dry mass) in NT and onecontrol treatment without millet residue(CT). In order to build up the soilcover, the millet crop was cultivated atdifferent sowing densities in the plots.At harvest and following millet drymass plots sampling a nal adjustment

was done by adding or subtracting cropresidue to match each treatment levelbefore transplanting of onion seedlings.In all NT

0.0t/haplots the millet crop was

not cultivated, however, a minimum ofnatural vegetation was kept while milletwas grown in the other plots. Relativelyspeaking, the NT crop residue ratesproportionated a soil cover of about 0,30, 60 and 90%, respectively, accordingto visual evaluation by three judges.

A population of onion-type BaiaPeriforme (CNPH 6400) was cultivated,belonging to the Breeding Program ofEmbrapa, which is ending development.Seedlings were grown in soil bedsinside a greenhouse and transplantedto plots by middle June in a 0.25-m x

0.07-m spacing, providing a stand of 476thousand plants per hectare. The totalarea of each plot was 38.4 m2 (6.4 x 6.0m) from which 12.8 m2 were harvestedfor evaluation of production variables.

In all NT plots the seedlings weretransplanted in small furrows (0.05 mwide, and 0.08 m deep) mechanicallyopened. On the other hand, the CTtreatment consisted of the mechanicaloperations of plowing, grading,furrowing, fertilization and transplant.To avoid soil compaction in NT plots, a4.0-m buffer surrounding CT plot wasleft. Preplanting fertilization was doneaccording to soil chemical analysiswith application of 1,000 kg ha-1 of theformula 04-30-16, and for side dressingfertilization 600 kg ha-1 of the formula20-0-20 split in three applications of 200

kg ha-1 at 20, 40, and 60 days followingseedlings transplant was applied. Theremaining cultural practices followedthe recommendations by Oliveira &Boiteux (2008).

A microsprinkler irrigation systemwas used in order to decrease plot size.The emitters were set up at a 2.0-m x2.0-m spacing with the application rateof 16.3 mm h-1 which resulted in fullsurface wetting cover. The Christiansencoefcient ranged between 80% and

90% as a function of wind conditions.Irrigation events followed a schedule

based on soil-water tension between 25and 30 kPa at crop 50% effective rootingdepth (Marouelli et al., 2005), i.e., 0.08m from transplant to beginning of bulbforming, and 0.15 m afterward. Thesoil water tension was measured usingtensiometers installed one per plot. Thedepth of applied water in each irrigationevent was sufcient to bring soil moisture

content to eld capacity (6 kPa) at the

onion effective rooting profile. Theeffective root depth was considered asthe prole depth with 80% of onion

roots concentration. The effective rootdepth was visually evaluated by openinga trench perpendicular to crop rows,in the buffer surrounding of CT plots.The crop irrigation events ceased whenabout 50% of leaves senesced and thetops have fallen naturally (Marouelli etal., 2005).

The crop was harvested 111 daysfrom seedlings transplant. The following

crop variables were evaluated: numberand average weight of non-marketablebulbs (90 mm); and canopy biomass (13% wetbasis). The crop production variables

were evaluated after bulb curing 30 daysafter harvest. To access post-harvestconservation of bulbs, the percentageof number of rotten bulbs caused bybacteria and fungus at 30 and 60 daysafter harvest were evaluated.

The water productivity index wasderived from bulb yield and totaldepth of applied water which is givenby the ratio of marketable bulb yieldto the volume of water effectivelyapplied through irrigation per unit area

(Jensen, 2007). The water applied wasdetermined based on the average depthfrom four pluviometers diagonallyinstalled above the crop canopy in oneplot at each treatment.

The ANOVA was applied to thedata and the variables affected by thedifferent crop residue covers in NT werefurther analyzed by a linear regressionusing orthogonal polynomials. Themultiple comparison Dunnett t testwas used to confront CT to NT treatmentaverages at 5% maximum level ofsignicance.

RESULTS AND DISCUSSION

The total rainfall occurred during thetest period was 4 mm, which probablyhad no effect on the results. Throughoutthe entire crop cycle irrigation eventsvaried between 31 and 39 for NT, andfor CT totaled 39 events (Table 1).Correspondently, the total depth ofwater applied during crop cycle rangedbetween 525 and 625 mm for NT, andtotaled 646 mm for CT (Table 1). Hence,compared to CT the water savings withNT were as much as 19%. Stone &Moreira (2000) and Marouelli et al.(2006) also veried signicant water

savings in studies with soil surfacecoverage with crop residues. Landers(1995) and Allen et al. (1998) reportedreduction in the average water use of15% in NT systems of different crops.

The current reduction in water

WA Marouelli et al.


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applied with the NT system was twicehigher than that observed in studies byMarouelli et al. (2006) with processingtomatoes under similar soil and climateconditions. Considering both cropsoil coverage capabilities, the waterlosses by evaporation of onion in CTare proportionally higher than that ofprocessing tomatoes cultivated in NT(Allen et al., 1998).

The water savings in NT are due toeffect of the soil coverage which worksas a barrier preventing water evaporationfrom soil surface. According to Stone& Moreira (2000), the crop residuecover initially acts in the soil-waterevaporation process by reducing the

daily evaporation rate due to higher solarradiation reection, and consequently,

the crop evapotranspiration.

If considered only the rst 30 days

after seedling transplant, the depth ofwater required for NT treatments withresidue covers was reduced between20 and 30% as compared to CT. Onthe other hand, water savings in NTtreatments were smaller for the last 30days of irrigation ranging between 5 and10% as compared to CT (Table 1). Themost water savings in NT treatmentsduring the onion initial developmentstage were due to the small fractionof soil covered by plants and to thefact surface evaporation accounts for

the most part of irrigation demand.At the end of crop cycle, when theplants cover most of the soil surface,transpiration becomes the major processin transferring water; hence, watersaving is attenuated (Derpsch et al.,1991; Stone & Moreira, 2000).

Ne ithe r NT nor CT tr ea tmen tsaffected signicantly (p>0.05) the crop

biomass production (in average 2.14t ha-1), total number of bulbs per unitarea (in average 44.3 bulbs m-2), and theweight of marketable bulbs (in average137.4 g). Consequently, bulb yields ofclass 2 (in average 2.4 t ha-1), class 3(in average 33.7 t ha-1), and class 4 (inaverage 20.1 t ha-1), and marketablebulbs (in average 56.2 t ha-1) were notaffected by the treatments. The bulbyield of class 5 was very small.

Apparently, the results of bulbyields reported above differ fromthose reported by Madeira & Oliveira(2005), who showed significantdifferences in onion bulb yield forboth NT and CT. The possible lack ofyield differences between both NT andCT treatments under the current studywas due to individualized irrigationwater management by treatment, withirrigations carried out at the right time(soil-water tension 25-30 kPa) and inadequate amount to meet the crop waterneeds, i.e., no excess or shortage. On theother hand, Madeira & Oliveira (2005)applied uniform irrigation events forboth NT and CT planting systems, whichmay have promoted conditions of excessor shortage of water for either system,hence affecting bulb yield.

Table 1. Number of irrigations and water depth effectively applied to onion cultivated in no-tillage (NT), with levels of crop residue coverup to 13.5 t ha-1, and conventional tillage systems (CT) during the rst 30 days after seedlings transplant, throughout crop cycle, and duringthe last 30 days of irrigation, and water savings in NT treatments compared to CT (quantidade total de irrigaes e lmina de gua efeti-vamente aplicada na cultura de cebola em sistemas de plantio direto (NT), com nveis de palhada at 13,5 t ha-1, e de plantio convencional(CT) durante os primeiros 30 dias aps o transplante de mudas, ao longo do ciclo e durante os ltimos 30 dias de irrigao, e economia douso de gua nos tratamentos NT em relao ao CT). Braslia, Embrapa Hortalias, 2007.

TreatmentNo. of

irrigations

First 30 days Last 30 days Entire cycle (111 days)

Waterdepth (mm)

Waterdepth (mm)

Watersavings (%)

Watersavings (%)

Waterdepth (mm)

Watersavings (%)

NT0.0 t/ha

39 117 305 2 3 625 3

NT4.5 t/ha

35 97 295 5 20 564 13

NT9.0 t/ha

33 91 289 7 25 540 16

NT13.5 t/ha

31 85 281 10 30 525 19

CT 39 121 312 -- -- 646 --

iWP = 9.45 + 0.1084X

R = 0.71

9,0

9,5

10,0

10,5

11,0

0,0 4,5 9,0 13,5

iW

P(kgm-3)

Cover crop residue (t ha-1)

Figure 1. Water productivity index (iWP) for onion crop according to the amount of crop

residue covering the soil in no-tillage system (funo de resposta para ndice de produtivi-

dade da gua (iWP) para a cultura de cebola, conforme a quantidade de palhada em sistema

de plantio direto). Braslia, Embrapa Hortalias, 2007.

Water use and onion crop production in no-tillage and conventional cropping systems

Cover crop residue (t ha-1)

iWP(kg

m-3)


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22 Hortic. bras., v. 28, n. 1, jan.- mar. 2010

Similarly to the yield componentvariables, NT and CT treatments didnot signicantly affect the postharvest

conservation of bulbs as evaluated bythe number of rotten bulbs at 30 days(in average 3.4%) and 60 days (inaverage 12.4%) of storage. According toMarouelliet al. (2005), excess irrigation

affects onion bulb storage conservation,in special during maturation cropdevelopment stage. In the present study,however, despite of the total depth ofirrigation water have varied betweentreatments, the conditions of soilmoisture that the plants were submittedin all treatments were similar. Therefore,no onion bulb storage conservationvariation was expected as a function oftreatments.

The water productivity index was

significantly affected by treatments(p

water use and onion crop production in no-tillage and conventional

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