Europ. J. Agronomy 21 (2004) 117–127

Studies on NPK drip fertigation in field grown tomato(Lycopersicon esculentumMill.)

S.S. Hebbarb, B.K. Ramachandrappaa,∗, H.V. Nanjappaa, M. Prabhakarb

a Department of Agronomy, University of Agricultural Sciences, Bangalore 560065, Karnataka, Indiab Indian Institute of Horticultural Research, Bangalore, India

Received 12 August 2002; received in revised form 11 July 2003; accepted 11 July 2003

Abstract

A field experiment was conducted during the summer seasons of 1999–2000 and 2000–2001 at the Main Research Station,University of Agricultural Sciences, Hebbal, Bangalore to study the effect of fertigation with sources and levels of fertilizer andmethods of fertilizer application on growth, yield and fertilizer-use efficiency of hybrid tomato in red sandy loam soil. Therewere eight treatments including furrow-irrigated and drip-irrigated controls, which was replicated three times. The investigationsrevealed that the total dry matter (TDM) production and leaf area index (LAI) were significantly higher in drip irrigation (165.8 gand 3.12, respectively) over furrow irrigation (140.2 g and 2.25, respectively). Water-soluble fertilizer (WSF) fertigation recordedsignificantly higher total dry matter and LAI (181.9 g and 3.69, respectively) over drip irrigation. Chlorophyll concentration wassignificantly higher in fertigation treatments over soil applied treatments at 90 DAT. The fruit yield of tomato was 19.9%higher in drip irrigation (71.9 Mg ha−1) over furrow irrigation (59.50 Mg ha−1). Fertigation with 100% WSF increased the fruityield significantly (79.2 Mg ha−1) over furrow-irrigated control and drip irrigation. Subsurface drip fertigation (76.55 Mg ha−1),nitrogen–potassium fertigation (76.57 Mg ha−1) and 1/2 soil–1/2 fertigation (76.51 Mg ha−1) had given fruit yields similar to WSFfertigation. Significant yield reduction was recorded with 75% rate fertigation (72.7 Mg ha−1) and normal fertilizer fertigation(73.27 Mg ha−1) compared to WSF fertigation. WSF fertigation recorded significantly higher number of fruits per plant (56.9)and fertilizer-use efficiency (226.48 kg yield kg−1 NPK) compared to drip- and furrow-irrigated controls. Fertigation resulted inlesser leaching of NO3-N and K to deeper layer of soil. Subsurface drip fertigation caused higher assimilable P in deeper layer.Root growth and NPK uptake was increased by WSF fertigation.© 2003 Elsevier B.V. All rights reserved.

Keywords:Tomato; Fertigation; Subsurface fertigation; Nutrient distribution in soil; Root growth; NPK uptake

∗ Corresponding author. Tel.:+91-80-3330153x287;fax: +91-80-3330684.

E-mail address:bkr agron@yahoo.co.in(B.K. Ramachandrappa).

1. Introduction

Tomato is one of the most popular and widely grownvegetable crops in the world. It responds well to theapplication of fertilizers and is reported to be a heavyfeeder of NPK. Efficient use of fertilizer and wa-ter is highly critical to sustained agricultural produc-tion. Fertilizers applied under traditional methods are

1161-0301/$ – see front matter © 2003 Elsevier B.V. All rights reserved.doi:10.1016/S1161-0301(03)00091-1

118 S.S. Hebbar et al. / Europ. J. Agronomy 21 (2004) 117–127

generally not utilized efficiently by the crop. In ferti-gation, nutrients are applied through emitters directlyinto the zone of maximum root activity and conse-quently fertilizer-use efficiency can be improved overconventional method of fertilizer application. Gener-ally crop response to fertilizer application through dripirrigation has been excellent and frequent nutrient ap-plications have improved the fertilizer-use efficiency(Malik et al., 1994). Bar Yosef and Sagiv (1982)re-ported fertilizer saving and increase in tomato yielddue to fertigation. Not much information is availableon different aspects of fertigation on closely spacedcrops like tomato under semiarid tropics. Therefore,the present investigation was conducted to study the ef-fect of fertigation involving the source and rate of fer-tilizers, methods of fertilizer application like throughsoil, drip irrigation, subsurface irrigation, combinationof soil and irrigation water, and combination of nutri-ents for fertigation on yield and quality of tomato.

2. Materials and methods

The experiment was conducted at the Main Re-search Station, University of Agricultural Sciences,Hebbal, Bangalore, India, during the November–Marchseason (mild winter to early summer) of 1999–2000and 2000–2001. The soil of the experimental site wasred sandy loam in texture, medium in organic carbon(0.65%) with a neutral pH (6.78). The available N, as-similable P and exchangeable K were 262.2, 40.4 and90.5 kg ha−1, respectively before the initiaton of firstyear experiment. The field capacity values for 0–15and 15–30 and 30–60 cm depths were 13.28, 17.16and 18.50% respectively, and the permanent wiltingpoint values for the corresponding depths were 6.91,10.00 and 11.06% respectively. The weather waswarm and rainfall of 65.9 and 21.4 mm was receivedduring respective cropping season. This entire rain-fall was considered as effective rainfall. The meanmonthly evaporation ranged from 2.9 to 5.6 mm andfrom 3.5 to 6.6 mm in the respective cropping sea-son. The actual mean maximum temperature rangedfrom 25.6 to 29.4◦C and from 26.1 to 33.0◦C in theyears 1999–2000 and 2000–2001. The variations inmean minimum temperature in growing months were14.6–17.5◦C and 13.2–19.5◦C respectively, for the2 years. Twenty-eight-day-old seedlings of tomato

Table 1Treatment details

T1: control Normal fertilizers applied to soilwith furrow irrigation

T2: drip irrigation Normal fertilizers applied to soilwith drip irrigation

T3: WSF fertigation 100% water-soluble fertilizer(WSF) applied through dripirrigation

T4: NF fertigation Normal fertilizers (NF) appliedthrough drip irrigation

T5: 75% rate fertigation 75% of the recommended rateof fertilizer as WSF appliedthrough drip irrigation

T6: 1/2 soil–1/2 fertigation Half the quantity of fertilizerapplied to soil as NF, other halfas WSF through drip irrigation

T7: NK fertigation P as NF applied to soil and Nand K as WSF applied throughdrip irrigation

T8: subsurface dripfertigation

100% WSF applied to soilthrough sub surface dripirrigation

Rate of fertilizer (for all treatments except T5): 180 kg N ha−1,66 kg P ha−1 and 99.6 kg K ha−1.

hybrid Arka Abhijit were transplanted to the mainfield on 17th November during 1999–2000 and 22ndNovember during 2000–2001, with the spacing of90 cm between the rows and 30 cm between the plantsin a row. The experiment was laid out in a random-ized complete block design having eight treatmentsas shown inTable 1. The treatments were replicatedthree times in 5.4 m × 4.8 m plot. The second yearexperiment was superimposed on the first year’s ex-perimental plot. The crop took 116 and 119 days,respectively, in 2 years of study from transplanting tofinal picking. Tomato fruits at ‘color breaker stage’were harvested. Eleven harvest from a period of 49days were taken up in first year and 10 harvests in46 days were made in the second year. The nor-mal fertilizers (NFs) used in the experiment wereurea, single super phosphate and muriate of potash,whereas, monoammonium phosphate (12–26.84–0),potassium nitrate (13–0–38.18) and urea formed thesource of 100% water-soluble fertilizer. The levelof fertilizer adopted in the present study was 180 kgN ha−1, 66 kg P ha−1 and 99.6 kg K ha−1, which isthe rate recommended by the University for the cropof Tomato. Fertilizer was injected in weekly intervalsthrough the in-line drippers. Soil applied treatments

S.S. Hebbar et al. / Europ. J. Agronomy 21 (2004) 117–127 119

received entire P and K at transplanting and N intwo splits that is, at transplanting and 28 days aftertransplanting. The fertilizers were incorporated intothe soil at a depth of 10 cm. Irrigation to all the treat-ments was scheduled based on evaporation replenish-ment (0.75 class “A” pan evaporation). Irrigation todrip irrigation treatments (T2–T8) were given dailythrough in-line drippers, whereas for furrow irrigationtreatment (T1) irrigation was given at 6 days intervalcumulating the previous 6 days evaporation. Therewere 17 and 19 irrigations in 2 years of experiments,respectively. Soil moisture content was determinedgravimetrically. The quantity of water applied to fur-row irrigation was measured using Parshall Flumeand to drip irrigation by water meter. Fertilizers wereinjected through the non-electrical proportional injec-tor from Dosatron International at a weekly intervalstarting from 7 days after transplanting (DAT) andcontinued up to 84 DAT. In-line dripper laterals wereburied at a depth of 20 cm from the soil surface be-fore transplanting for subsurface drip fertigation. Thechlorophyll concentration of the leaves at 90 days af-ter transplanting was determined as given byHiscoxand Isrealstam (1979). Observations on growth, yieldparameter and yield were made. Fertilizer-use effi-ciency was worked out as a factor of total economicyield from all harvests by quantity of fertilizer ap-plied and expressed as %. The nitrogen (modifiedKjeldkal’s) phosphorus (molybdo-phosphoric acidyellow color in HNO3 system) and potassium concen-tration (diacid digested samples in flame photometer)in oven dried entire plant part was estimated. Fromthe concentration of NPK in stem, leaf and fruits at120 days after transplanting, NPK uptake was workedout by multiplying the NPK concentration in plantpart with the respective dry weight of plant part, fromwhich the uptake per hectare was derived based onplant population. Soils were analyzed for availableN (alkaline potassium permanganate method), assim-ilable P (Brays I), exchangeable K (neutral normalammonium acetate extraction) and NO3-N (alkalinepotassium permanganate method and two-stage dis-tillation with Devarda’s Alloy). Root studies werecarried out by exposing the network of roots by meansof opening the trench at a distance of 90 cm from theplant base and washing off the soil around the plantthrough jet of water. Soil moisture content was deter-mined gravimetrically. Fruit quality parameter such

as firmness (pocket penetrometer or fruit pressuretester, with a probe diameter of 0.8 cm and valuesexpressed in pounds), total soluble solids (hand heldBrix Meter), titrable acidity (titration method), andascorbic acid concentration (visual titration method)were determined using standard procedure.

3. Results and discussion

3.1. Growth

Economic yield is a part of the total biologicalyield of the crop and hence the dry matter productionis an important determinant of the economic yield.The total dry matter accumulation per plant at fi-nal harvest was significantly higher in drip irriga-tion (165.8 g) over furrow irrigation control (140.2 g)(Table 2). Further, significantly higher dry weight perplant was observed with WSF fertigation (181.9 g)over drip irrigation. However, the total dry weightper plant at harvest did not differ significantly amongWSF fertigation (181.9 g), sub surface drip fertigation(178.2 g), NK fertigation (181.1 g) and 1/2 soil–1/2fertigation (177.4 g). The difference in the dry mat-ter production due to different treatments can be as-cribed to the leaf area production. Leaf area index isthe measure of source size and significantly higher leafarea index was recorded with WSF fertigation (3.69)over furrow-irrigated control (2.25) and drip irrigation(3.12) NF fertigation (3.19), and 75% rate fertigation(3.19). Higher LAI contributed for more carbohydratesynthesis and better yield. The importance of canopystructure in light interception, crop growth and yieldhas been pointed out byDuncan (1971). Higher LAIwith drip irrigation than furrow irrigation has been re-ported byChawla and Narda (2000). Shoot length wassignificantly superior in all the drip and fertigationtreatment over soil applied furrow-irrigated control.

3.2. Chlorophyll concentration

Chlorophyll (a+ b) was significantly higher in allthe fertigation treatments (T3–T8) over the soil appliedtreatments namely, furrow-irrigated control (T1) anddrip irrigation (T2) at 90 DAT. This is the testimonyfor the longer source activity in fertigation where nu-trients were applied through 9–12 split doses to match

120 S.S. Hebbar et al. / Europ. J. Agronomy 21 (2004) 117–127

Table 2Growth parameters in tomato as influenced by fertigation with sources and levels of fertilizers and methods of fertilizer application (pooleddata of 2 years)

Treatments Plant height atfinal harvest (cm)

Leaf area index(LAI) at 90 DAT

Total dry weight at finalharvest (g per plant)

Chlorophyll (a+ b)concentration at 90 DAT(mg g−1 fresh weight)

T1: control 69.2 2.25 140.2 0.80T2: drip irrigation 80.8 3.12 165.8 0.88T3: WSF fertigation 82.3 3.69 181.9 1.44T4: NF fertigation 79.8 3.19 164.6 1.31T5: 75% rate fertigation 79.4 3.19 163.7 1.39T6: 1/2 soil–1/2 fertigation 81.6 3.48 177.4 1.33T7: NK fertigation 79.6 3.33 181.1 1.39T8: subsurface drip fertigation 81.1 3.39 178.2 1.41S.E.M. ±2.0 ±0.13 ±3.3 ±0.14C.D. (P = 0.05) 5.7 0.36 9.4 0.43

DAT: days after transplanting.

the uptake by crop. This enhanced the current photo-synthesis for developing fruit leading to the develop-ment of fruit to marketable size and producing morenumber of fruits per plant in fertigation treatmentscompared to soil application treatments (Table 2).

3.3. Yield and yield components

3.3.1. Furrow and drip irrigationDrip irrigation with soil application of fertilizer (T2:

71.92 Mg ha−1) registered significantly higher yield

Table 3Yield, yield components and fertilizer-use efficiency in tomato as influenced by fertigation with sources and levels of fertilizer and methodsof fertilizer application (pooled data of 2 years)

Treatments Number offlowers perplant at 60DAT

Number offruits per plant

Mean fruitweight (g)

Fruit yield(kg per plant)

Marketable fruityield (Mg ha−1)

Fertilizer useefficacy(kg yield kg−1

NPK)

T1: control 29.6 43.7 54.2 1.67 59.50 170.0T2: drip irrigation 36.1 50.4 54.7 2.12 71.92 205.5T3: WSF fertigation 38.3 56.9 56.7 2.35 79.27 226.5T4: NF fertigation 31.5 51.6 55.1 2.09 73.27 209.3T5: 75% rate

fertigation32.2 52.0 56.2 2.13 72.70 207.7

T6: 1/2 soil–1/2fertigation

33.0 55.1 55.6 2.27 76.51 218.6

T7: NK fertigation 35.3 55.4 55.6 2.29 76.57 218.8T8: subsurface

drip fertigation36.8 53.9 58.1 2.27 76.55 218.7

S.E.M. ±1.9 ±1.1 ±1.1 ±0.05 ±1.68 ±4.8C.D. (P = 0.05) 5.6 3.2 NS 0.15 4.85 13.9

DAT: days after transplanting; NS: non-significant.

over furrow irrigation with soil application of fertilizer(T1: 59.50 Mg ha−1) which amounted to 19.9% yieldincrease over control (T1) (Table 3). This yield in-crease can be attributed to significantly higher numberof flowers and fruits per plant and fruit yield per plantin drip irrigation over furrow irrigation. The betterperformance under drip was attributed to maintenanceof favorable soil water status in the root zone, whichin turn helped the plants to utilize moisture as well asnutrients more efficiently from the limited wetted area(Phene and Beale, 1976). The water quantity used

S.S. Hebbar et al. / Europ. J. Agronomy 21 (2004) 117–127 121

Table 4Percentage available water before an irrigation cycle in furrow anddrip irrigation

Treatments Percentage available water before anirrigation cycle

0–15a 15–30a 30–45a 45–60a

T1 40.6 (9.5) 43.3 (13.1) 45.5 (14.5) 64.5 (15.9)T2 95.4 (13.0) 76.7 (15.5) 72.7 (16.5) 78.1 (16.9)

Figures in parenthesis are the actual soil moisture % determinedgravimetrically.

a Sampling depth (cm).

was same for all the treatments including furrow irri-gation. It was 587.5 mm (90 mm as common surfaceirrigation, 65.9 mm as effective rainfall and remaining431.6 mm as irrigation water) in the year 1999–2000.The water use quantity for 2000–2001 were 90 mmas common surface irrigation to all the treatments,21.4 mm effective rainfall and remaining 522.7 mmas irrigation water applied through furrow/drip ir-rigation, summing up to 634.1 mm for the season.The % available water just before irrigation rangedfrom 40.6% in top 15 cm layer to 64.5% in 45–60 cmdepth in furrow irrigation (T1), whereas for drip ir-rigation (T2), the corresponding values were 95.4and 78.1% (Table 4). This shows the more favorablemoisture regime in drip irrigation compared to furrowirrigation.

3.3.2. Drip irrigation compared with drip fertigationThe distinctive yield advantage reflected in drip

irrigation over furrow irrigation is further amplifiedby the application of fertilizers through drip irriga-tion water. Fertigation treatments (T3–T8) resulted inhigher fruit yield (72.70–79.27 Mg ha−1) over drip ir-rigation. Significantly higher fruit yield in WSF fer-tigation (T3: 79.27 Mg ha−1) over drip irrigation wasobserved, which accounted for 10.2% yield increase.Significantly higher number of fruits per plant andfruit yield per plant was recorded with drip fertigationover drip irrigation. Similar results of improved yieldhave been reported byIbrahim (1992)andLara et al.(1996).

3.3.3. Levels of fertilizer for fertigationMarketable fruit yield per ha was significantly lower

in 75% rate fertigation (T5: 72.7 Mg ha−1) than WSF

fertigation, which accounted to 8% yield reduction.The soil of the experimental site was low in avail-able nitrogen (262.4 kg ha−1) and low in exchange-able potassium (90.5 kg ha−1). Besides, the high yieldpotential hybrid tried in the present study was ex-pected to respond better at still higher fertilizer rate.Because of these reasons, the yield was significantlylower with 75% rate fertigation over WSF fertigation.The reduction in yield with 75% rate fertigation is inagreement with the findings ofAramini et al. (1995).However, the yield in 75% rate treatment (T5) wason par with all other fertigation treatments and dripirrigation.

3.3.4. Source of fertilizer for fertigationFertigation with normal fertilizers (T4: 73.27 Mg

ha−1) gave significantly lower yield comparedto fertigation with water-soluble fertilizers (T3:79.27 Mg ha−1). This was attributed to complete sol-ubility and availability of the WSF as compared tonormal fertilizers. Water-soluble fertilizer fertiga-tion (T3) had higher concentration of available plantnutrients in top layer (Figs. 1–3) over normal fertil-izer (T4) thus increasing the marketable fruit yieldof tomato. However, yield under NF fertigation wasequal with all other treatments except furrow irri-gation. In fertigation, use of 100% water-solublefertilizer is recognized to safe guard the drip systemin a long run. The normal fertilizer generally tendsto clog the emitters and cause uneven distribution offertilizers. However, in the present study of 2 years,no clogging of emitters was observed.

3.3.5. NK fertigationNutrients such as N and K are commonly applied

through drip system, while P is more difficult to applyand to obtain proper distribution in soil. Because ofthe tendency of P to form insoluble precipitate with Caand Mg commonly found in irrigation water, the use oftraditional P fertilizer in drip irrigation is not very com-mon. In the present study, the fruit yield of tomato inNK fertigation (T7: 76.57 Mg ha−1) did not differ sig-nificantly from WSF fertigation (T3: 79.27 Mg ha−1).This suggests lesser response to P fertigation com-pared to NK fertigation. Since the requirements oftomato crop for N and K also is very high, fertigationof N and K produced similar yields as that of NPKfertigation.

122 S.S. Hebbar et al. / Europ. J. Agronomy 21 (2004) 117–127

0

20

40

60

80

100

120

0-15cm 15-30cm 30-45cm 45-60cm

Soil depths (cm)

Res

idua

l NO

3-N

(kg

ha-1

)

T1T2T3T4T5T6T7T8

T5

T1

T2

T3T4

T6

T7

T8

Fig. 1. Residual NO3-N at different soil depths as influenced by fertigation (pooled data of 2 years).

3.3.6. Methods of fertilizer applicationThe marketable fruit yield obtained under 1/2

soil–1/2 fertigation (T6: 76.51 Mg ha−1) was equalwith WSF fertigation (T3: 79.27 Mg ha−1), whichis in agreement with the findings ofLocascio et al.(1997). In another method of fertilizer applicationnamely through subsurface fertigation, the fruit yieldof tomato (76.55 Mg ha−1) recorded was equal to thatrecorded in WSF fertigation (T3: 79.27 Mg ha−1) andsignificantly superior to drip and furrow irrigation.This higher yield in subsurface drip fertigation overdrip and furrow irrigation was due to the supply ofnutrients and soil moisture at the center of active rootdevelopment. Comparable yields from subsurface dripfertigation to regular fertigation have been reportedby Hernandize et al. (1991).

Increase in fruit yield per plant could be related tosignificantly higher number of fruits per plant in dripirrigation (T2: 50.4) over furrow irrigation (T1: 43.7)and in WSF fertigation (T3: 56.9) over drip irrigation(T2) (Table 3). Mean fruit weight did not vary sig-

nificantly among the treatments. Significantly highernumber of flowers per plant was recorded at 60 DATin drip and fertigation treatments (T2–T8) over con-trol (T1). Fruit yield per plant was also significantlyhigher in WSF fertigation (T3: 2.35 kg per plant) com-pared to control (1.67 kg per plant) and drip irrigation(2.12 kg per plant).

3.4. Fertilizer-use efficiency (FUE)

Fertilizer-use efficiency was significantly superiorin all the treatments where either drip irrigation (T2)or fertigation (T3–T8) was followed over furrow ir-rigation (T1: 170 kg kg−1 NPK) (Table 3). This wasdue to better availability of moisture and nutrientsthroughout the growth stages in drip and fertigationsystem leading to better uptake of nutrients and pro-duction of tomato fruits. FUE was significantly higherin WSF fertigation (T3: 226.48 kg ha−1) compared todrip irrigation (T2: 205.47 kg), 75% rate fertigation(T5: 207.73 kg) and NF fertigation (T4: 209.34 kg).

S.S. Hebbar et al. / Europ. J. Agronomy 21 (2004) 117–127 123

0

20

40

60

80

100

120

0-15cm 15-30cm 30-45cm 45-60cm

Soil depths (cm)

Ass

imila

ble

P (

kg h

a-1)

T1

T2

T3

T4

T5

T6

T7

T8

T1T2

T3

T4 T5

T6

T7

T8

Fig. 2. Residual assimilable P at different depths of soil as influenced by fertigation (pooled data of 2 year).

3.5. Nutrient distribution in soil

Lower NO3-N was observed at 30–45 cm soillayer in fertigation treatments such as WSF ferti-gation (55 kg ha−1), NF fertigation (54 kg ha−1) andNK fertigation (53 kg ha−1) compared to entirely soilapplied treatments such as control (65 kg ha−1) anddrip irrigation (66 kg ha−1) (Fig. 1). Similar trend ofNO3-N distribution was recorded in 45–60 cm layer,which was due to higher amount of leaching fractionof fertilizer applied.Alva and Mozzafari (1995)alsoreported that fertigation treatments maintained highconcentration of NO3-N at shallow depth than deeperlayer.

Assimilable P distribution in soil at all layerswas at a higher levels (>24.2 kg ha−1) except at adeeper depth of 45–60 cm (Fig. 2). The accumulationof assimilable P at 0–15 and 15–30 cm was signif-icantly higher in WSF fertigation (111.4 kg ha−1)

because of complete solubility of mono ammo-nium phosphate and frequent and small applicationrates compared to soil application (92.8 kg ha−1),drip irrigation (95.2 kg ha−1) and NK fertigation(97.3 kg ha−1). The level of assimilable P was signif-icantly higher in 15–30 cm (62.0 kg ha−1), 30–45 cm(35.6 kg ha−1) and 45–60 cm (22.4 kg ha−1) depthsin subsurface drip irrigation compared to other treat-ment because P fertilizer was delivered 20 cm belowthe surface by means buried laterals. P fertilizers aremore prone to fixation at the point of application.Since the point of application was deeper by 20 cm,more concentration of P was observed at deeperdepths.

Exchangeable K accumulation was higher at deeperlayers (45–60 cm) in furrow (92.9 kg ha−1) and dripirrigation (95.4 kg ha−1) where entire K fertilizer wasone time soil applied, indicating potential leachingrisk (Fig. 3). The leaching aspect under one time soil

124 S.S. Hebbar et al. / Europ. J. Agronomy 21 (2004) 117–127

70

75

80

85

90

95

100

105

0-15cm 15-30cm 30-45cm 45-60cm

Soil depths (cm)

Res

idua

l K (

kg h

a-1)

T1

T2

T3

T4

T5

T6

T7

T8

T1

T2

T3

T4T5

T6

T7

T8

Fig. 3. Residual exchangeable K in different soil depths as influenced by fertigation in tomato (pooled data of 2 years).

application followed by irrigation can be related tothe study ofPapadopoulos (1988).

3.6. Root characteristics

Optimum root growth and distribution is needed forproper shoot anchorage, water and nutrient uptake andcrop yield. Majority of the roots were between 0 and25 cm, and below this depth, only a few roots wereobserved. This is the major cause for variation in yieldamong the treatments. Further, we have also observeda hard soil layer at 35–45 cm depth, which could bethe reason for poor root proliferation at deeper layer.Although tomato is deep-rooted crop and can stretchup to 120 cm depth, as observed in literature, thiswas not observed in the present study. Therefore theamount of nutrient present in top 30 cm soil layerinfluenced the yield in different treatments. Frequentsupplementation of nutrients with irrigation water in-

creased the availability of N, P and K in the crop rootzone and which in turn influenced the root growth.This is also evidenced by the significantly highernumber of primary roots (13.8–15.3), fibrous rootsarising from stem base (30.3–34.0), maximum rootlength (82.8–91.2 cm) and average length of primaryroots (44.2–50.3 cm) in fertigation treatments (T3–T8)compared to soil applied treatment (T1) (12.0, 14.3,61.7 and 27.7 cm, respectively) (Table 5). Root dryweight was significantly higher (13.9–16.2 g per plant)in fertigation treatments compared to soil applicationtreatments (10.2–10.7 g) (Table 5). These results arein line with the findings ofZang et al. (1996).

3.7. Uptake of NPK

WSF fertigation had significantly higher N, P andK uptake over drip irrigation and control (Table 5).Uptake of nitrogen in subsurface drip fertigation, NK

S.S

.H

eb

ba

re

ta

l./

Eu

rop

.J.Ag

ron

om

y2

1(2

00

4)

11

7–

12

7125

Table 5Root characteristics and NPK uptake at final harvest in tomato as influenced by fertigation with sources and levels of fertilizer and methods of fertilizer application (pooleddata of 2 years)

Treatments Maximumlinear rootlength (cm)

Mean lengthof primaryroots (cm)

Number ofprimaryroots

Number offibrous rootsarising fromstem base

Root dryweight (gper plant)

Max. depth ofpenetration(cm)

Nutrient up take(kg ha−1)

N P K

T1: control 61.7 27.7 12.0 14.3 10.2 36.2 109.3 9.5 69.1T2: drip irrigation 79.5 46.5 13.7 26.8 10.7 49.0 142.1 13.3 94.3T3: WSF fertigation 91.2 50.3 15.3 34.0 16.2 48.0 165.7 16.5 113.5T4: NF fertigation 86.8 46.8 14.0 31.0 14.2 51.3 144.1 12.8 100.7T5: 75% rate fertigation 82.8 44.5 13.8 31.0 13.9 49.2 140.5 12.9 92.3T6: 1/2 soil–1/2 fertigation 87.3 44.2 15.2 33.7 15.8 55.5 161.9 15.3 105.2T7: NK fertigation 88.7 48.5 15.0 30.3 15.8 48.7 163.4 14.4 109.9T8: subsurface drip fertigation 85.5 48.7 15.7 33.8 15.1 52.0 161.3 15.4 110.6S.E.M. ±2.7 ±1.6 ±0.6 ±1.2 ±0.9 ±1.9 ±3.3 ±0.5 ±3.1C.D. (P = 0.05) 7.8 4.6 1.7 3.4 2.7 5.6 9.6 1.3 8.8

126 S.S. Hebbar et al. / Europ. J. Agronomy 21 (2004) 117–127

Table 6NPK concentration (mg g−1 dry matter) in stem, leaf and fruits at final harvesting stage in tomato as influenced by fertigation and irrigationmethods (pooled data of 2 years)

Treatments Stem Leaf Fruit

N P K N P K N P K

T1 0.129 0.013 0.093 0.158 0.031 0.065 0.333 0.018 0.225T2 0.122 0.018 0.109 0.161 0.032 0.065 0.375 0.022 0.262T3 0.142 0.022 0.113 0.168 0.035 0.069 0.390 0.024 0.288T4 0.118 0.019 0.110 0.166 0.029 0.069 0.381 0.022 0.288T5 0.130 0.019 0.096 0.159 0.029 0.068 0.368 0.022 0.258T6 0.138 0.023 0.111 0.169 0.033 0.067 0.396 0.023 0.276T7 0.133 0.019 0.115 0.170 0.031 0.067 0.398 0.022 0.286T8 0.138 0.024 0.109 0.168 0.033 0.072 0.394 0.023 0.291S.E.M. ±0.004 ±0.001 ±0.005 ±0.004 ±0.001 ±0.005 ±0.008 ±0.001 ±0.007C.D. at 5% 0.011 0.004 0.014 NS NS NS 0.023 0.003 0.021

fertigation and 1/2 soil–1/2 fertigation remained closeto WSF fertigation. Similar trend in the uptake of Pand K was noticed. The higher uptake was the result ofsignificantly higher dry matter production at 120 DAT(Table 2). Secondly, there was no dilution of NPK asdry matter production per plant increased in differentplant parts and concentration of the nutrients in plantparts also followed the trend of total uptake (Table 6).Also, fertilizer application through fertigation had animpact on the K concentrations in stem, leaves andfruits (Table 6). This increase in uptake per plant wasdue to the better availability of nutrients in root zoneas a result of frequent application of nutrients coupledwith better root activity. Further, it was also due to thereduced loss of nutrients primarily because of leachingin fertigation compared to soil application of fertilizer.Similar observations of increased uptake as a result of

Table 7Total soluble solids (Brix), fruit firmness, titrable acidity and ascorbic acid concentration in tomato as influenced by fertigation and irrigation

Treatments TSS (Brix) Fruit Firmness (lbs) Titrable acidity (% citric acid) Ascorbic acid (mg 100 g−1 fresh weight)

T1 3.95 7.35 0.40 16.00T2 4.12 7.43 0.41 16.67T3 4.22 8.39 0.46 19.33T4 4.15 7.98 0.43 17.33T5 4.03 8.27 0.42 17.67T6 4.13 8.68 0.45 19.00T7 4.25 8.68 0.44 17.33T8 4.28 8.23 0.46 18.00S.E.M. ±0.16 ±0.47 ±0.01 ±0.39C.D at 5% NS NS 0.04 1.17

TSS: total soluble solids; NS: non-significant.

fertigation have been reported earlier byVasane et al.(1996).

3.8. Quality parameters

This study revealed significant difference in titra-ble acidity and ascorbic acid concentration whileother quality parameters remained equal with eachother. Ascorbic acid concentration was significantlyhigher in WSF fertigation (T3: 19.33 mg 100 g−1 freshweight) compared to furrow irrigation (T1: 16.00 mg)and drip irrigation (T2: 16.67 mg) (Table 7). Fertilizerapplication method and also type of K fertilizer ap-plied had a positive impact on ascorbic acid concen-tration in fruits (Table 7) due to the better availabilityof K to the plant. This is consistent with the researchfindings ofAnac and Colcoglu (1995)who found that

S.S. Hebbar et al. / Europ. J. Agronomy 21 (2004) 117–127 127

K increased the ascorbic acid concentration in tomatofruits. Similar trend was observed with respect totitrable acidity. Therefore, it can be said that avail-ability of nutrients evenly with WSF fertigation (T3)was responsible for the improvement of ascorbic acidand titrable acidity.

4. Conclusion

This study has shown that fertigation with 100%water-soluble fertilizer increased the fruit yield oftomato significantly over furrow irrigation and dripirrigation. This accounted for 33 and 10% increase infruit yield, respectively. Subsurface drip fertigation,NK fertigation and 1/2 soil–1/2 fertigation was alsofound equally promising to WSF fertigation. Higherfruit yield in fertigation was brought about by thehigher leaf area index, total dry matter production,number of fruits per plant and higher fertilizer-useefficiency. Fertigation resulted in lesser leaching ofNO3-N and K to deeper layer of soil. Subsurface dripfertigation caused significantly higher assimilable Pat deeper depths. Phosphorus is prone to fixation atthe point of application and subsurface placement oflaterals at 20 cm depth resulted in more assimilableP at deeper depth compared to surface P appliedtreatments. Root growth and NPK uptake was higherwith WSF fertigation. Even availability of nutrientswith WSF fertigation resulted in the improvement ofascorbic acid concentration and titrable acidity.

References

Alva, A.K., Mozzafari, M., 1995. Nitrate leaching in a deepsandy soils as influenced by dry broadcast of fertigation ofnitrogen for citrus production. In: International Symposium OnFertigation Technology, Israel, 26–31 March 1995, pp. 67–77.

Anac, D., Colcoglu, H., 1995. Response of some major crops to Kfertilization. In: Mengel, K., Krauss, A. (Eds.), K Availabilityof Soils in West Asia and North Africa-Status and Perspectives.International Potash Institute, pp. 235–247.

Aramini, G., Catania, F., Colloca, L., Oppedisano, R., Paone,R., 1995. Fertilizer trial on tomatoes for fresh consumption.Colture-Protette 24 (5), 83–86.

Bar Yosef, B., Sagiv, B., 1982. Response of tomatoes to N andwater applied via trickle irrigation system. I. Nitrogen. Agron.J. 74, 633–637.

Chawla, J.K., Narda, N.K., 2000. Growth parameters of tricklefertigated potato. Indian J. Agric. Sci. 70 (11), 747–752.

Duncan, W.G., 1971. Leaf angle, leaf area and canopyphotosynthesis. Crop. Sci. 11, 482–485.

Hernandize, J.J.M., Bar-Yosef, B., Kafkafi, U., 1991. Effect ofsurface and subsurface drip fertigation on sweet corn rooting,uptake, dry matter production and yield. Irrig. Sci. 12, 153–159.

Hiscox, J.D., Isrealstam, G.F., 1979. A method for the extractionof chlorophyll from leaf tissues without maceration. Can. J.Bot. 57, 1332–1334.

Ibrahim, A., 1992. Fertilization and irrigation management fortomato production under arid conditions. Egyptian J. Soil Sci.32 (1), 81–96.

Lara, D., Adjanohoun, A., Ruiz, J., 1996. Response of tomatoessown in the non-optimal season to fertigation on a compactedred ferralitic soil. Cultivar Tropicales 17 (1), 8–9.

Locascio, S.J., Hochmuth, C.J., Olson, S.M., Hochmuth, R.C.,Csizinszky, A.A., Shuler, K.D., 1997. Potassium source andrate for polyethylene mulched tomatoes. Hort. Sci. 32 (7),1204–1207.

Malik, R.S., Kumar, K., Bhandari, A.R., 1994. Effect of ureaapplication through drip irrigation system on nitrate distributionin loamy sand soils and pea yield. J. Indian Soc. Soil Sci.42 (1), 6–10.

Papadopoulos, I., 1988. Nitrogen fertigation of trickle irrigatedpotato. Fertil. Res. 16 (2), 157–167.

Phene, C.J., Beale, D.W., 1976. High-frequency irrigation for waternutrient management in humid regions. Soil Sci. Soc. Am. J.40, 430–436.

Vasane, S.R., Bhoi, P.G., Patil, A.S., Tumbare, A.D., 1996. Effectof liquid fertilizer through drip irrigation on yield and NPKuptake of tomato. J. Maharashtra Agric. Univ. 21 (3), 488–489.

Zang, M., Alva, A.K., Calvert, D.V., 1996. Root distribution ofgrape fruit trees under dry granula broadcast vs. fertigationmethod. Plant Soil 183 (1), 79–84.