Agricultural water management

ELSEVIER Agricultural Water Management 25 (1994) 179-184

Effect of drip irrigation and mulching on tomato yield

P.K. Shrivastava*, M.M. Parikh, N.G. Sawani, S. Raman Water Management Project, Gujarat Agricultural University, Navsari Campus, Navsari-396 450, Gujarat, India

(Accepted 31 August 1993 )

Abstract

Experiments were conducted on the fine-textured heavy soils of Western India from 1989 to 1991. These sought to study the effect of drip, mulches and irrigation levels on tomato yield. The treatments comprised various combinations of two irrigation methods namely, drip and surface flood, with and without two mulches of either black plastic of sugarcane trash. For drip, three irrigation levels viz. 0.4, 0.6 and 0.8 fractions of pan evaporation (PE) were tried. In surface flood, the recommended irrigation schedule, i.e. 8 cm depth of irrigation at 100 mm cumulative pan evaporation (CPE), was followed. This study revealed that drip plus sugarcane trash mulch (STM) scheduled at 0.4 PE level was the best combination, which gave the highest fruit yield of about 51 metric tonne, ha- ~ with 44% water saving. The highest yield of 163 kg/ha/mm of water used was also maximum in this treatment. In areas of high weed intensity, drip at 0.4 PE along with plastic mulch (PM) could be adopted. This treatment resulted in 95 % reduction in weed infestation, 53% higher yield and 44% saving in irrigation water when compared with the surface flood without mulch treatment.

Key words: Drip irrigation; Mulching, organic, plastic; Tomato yield; Water economy

1. Introduction

Drip irrigation, with its ability of small, frequent irrigation applications, has created interest because of decreased water requirements and possible increased production. Small but frequent applications enable the plant to grow well without any ill efect of water-stress periods between consecutive irrigations. Large numbers of experiments have been con- ducted to study the response of various vegetable crops to drip irrigation and the response by tomato crop in terms of yield improvement was found to be different in different agro-

*Corresponding author.

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180 P.K. .'¢hrivastava cl ai ~t:rtc,ltura/ Pv#¢t~.r Man~ .c ,u ' , l 25 t 1994) 179 /,~4

climatic and soil conditions. About 30-50% higher tomato yields were obtained with drip irrigation in some studies (Bernstein and Francois, 1973: Torantino and Rubino, 1982), while in other studies the yields were reported to be slightly lower or equal to that of coventional surface flood irrigation (Doss et al., 1980; Bangal and Khaire, 1982; Pasternak et al., 1986: Singh et al., 1990). In the above-mentioned studies, the irrigation water requirements were reported to be reduced by 30-60%. Most of the results are from the agro- climatic conditions of arid zones and light-textured soils. The response of tomato to drip, mulches, and irrigation levels under sub-humid climatic and fine-textured heavy soil con- ditions, is not well known. Mulches also contribute to the crop production by way of influencing soil productivity, control of weed etc., depending upon the type of mulch (Sweeney et al., 1987; Asiegha, 1991 ). Very few workers studied the combined effect of drip with mulch on yield of tomato. Hence, this project was taken up to study the economic viability of drip irrigation in conjunction with mulch on tomato grown on the fine-textured heavy soils of Western India.

2. Materials and methods

In order to evaluate the drip irrigation along with mulches on tomato, experiments were conducted during the winter seasons of 1989, 1990 and 1991 at the Soil-Water Management Project Farm, Navsari, which is situated in South Gujarat, India, at 21 North latitude and 72 East longitude at an altitude of l0 m above mean sea level. The mean maximum and minimum temperature ranges from 26 to 36°C and 9.4 to 25.4°C respectively, with humidity ranging from 60 to 97% and 24 to 82%, respectively. The soil is clayey (63% clay), with density and basic infiltration rate as t .43 g c m 3 and 0.3 cm. h - 1, respectively. The available moisture content of the soil (AWC) is 15% by weight. The soil is classified as Vertic Ustrochrepts.

To achieve the objective of the experiment, 12 treatments were tried. There were nine treatments of drip in which all the combinations of three levels of moisture regimes viz. 0.4, 0.6 and 0.8 fractions of pan evaporations (PE) and three mulch treatments viz. no mulch, black plastic mulch (PM) and sugarcane trash mulch (STM) and three treatments of surface method viz. no mulch, black PM and STM at a fixed 0.8 irrigation depth to CPE ( IW/CPE) ratio. The depth of irrigation water was 8 cm. Parshall flume was used to measure the water. In drip, alternate day irrigations was followed and the quantity of total water applied was calculated over 2 days CPE values. The class A type USWE Pan Eva- porameter was used for finding the daily evaporation. The experiment was conducted on large-sized plots (60 m 2) and sample plot technique was used for statistical analysis. The sample size of each treatment was four. The plot size of individual treatment was 60 m 2 ( 15 X 4 m). The seedlings (Hybrid Tomato var. Rupali) were transplanted at a spacing of l × 0.5 m. A buffer strip of 1 m was left between two plots.

High density polythelene pipes of 5 cm diameter were used as main and sub-main lines and 1.3 cm diameter low density polythelene pipes as lateral. The lateral lines were laid parallel to crop rows. Each lateral was provided "On line" emitters of 1.11 × 1 0 - 6 m 3- s - 1 (4 l /h) capacity and spaced at l -m intervals. Each emitter was placed in such a way that it served two plants. The main line was directly connected to a 3 hp centrifugal pump installed

P.K. Shrivastava et al. /Agricultural Water Management 25 (1994) 179-184 181

to lift water from a water tank. The manifold unit consisted of a screen filter ( 140 mesh), pressure gauge and control valve. The system was operated at a constant pressure of 120 kPa (1.2 kg. cm -2 or 17.5 psi) which was maintained with the help of the control valve. Each lateral was provided with a 15 mm wheel valve in order to deliver the desired quantity of water to each treatment. The black plastic of 100/xm thickness ( 400 gauge) and sugarcane trash at the rate of 1 kg. m-2 was mulched in their respective plots with 10% soil surface area coverage.

In order to evaluate the relative effectiveness of each treatment, the data on yield, total water applied, and weed growth were collected. The total cost of production and the total income from the produce were considered to work out the net income. The effective cost per hectare for drip system and PM was worked out to be $665 and $485, respectively, which included depreciation, interest on investment and maintenance costs. The useful life of the drip system and PM was considered to be 8 and 4 years, respectively. The selling price of surface flood and drip irrigation tomato was $64.5 and $71 per metric tonne, respectively.

3. Results and discussion

The mean data on tomato yield, water applied, economic yield per unit water used, and weed growth as influenced by irrigation methods, levels and mulches are presented in Table 1.

Since this experiment was based on PE values, there was no difference in the water saving among drip and mulch with surface method when irrigation was done at the same ratio. The

Table 1 Tomato yield, water applied, economic yield per unit water used, and weed growth, as influenced by irrigation methods, levels and mulches (3 years' mean results)

Treatment* Tomato Water Yield per Weed yield applied unit water growth ( t .ha -1) (mm) used ( g . m -2)

( k g . h a - I m m -I )

Drip alone 0.4 1 0.6 2 0.8 3

Drip + PM 0.4 4 0.6 5 0.8 6

Drip + STM 0.4 7 0.6 8 0.8 9

Surface + PM 10 Surface + STM 11 Surface, No mulch 12

42 313 134 57 44 442 100 47 46 566 81 56 50 313 160 6 42 442 95 8 43 566 76 3 51 313 163 8 50 442 113 25 44 566 78 23 42 560 75 30 41 560 73 91 32 560 57 125

*Treatments are listed in the Materials and Methods.

182 17. K, Shrivasta va et al / A ~,ri~ultural Water Management 25 (1994) 179 /~4

Table 2

Economic analysis of various treatments for tomato crop ( US$ per ha)

Treatment Total cost Total Net income Extra

of production receipt income

l'Fo nl o v e r

produce treatment 12

P e r c e n t i n c r e a s e ill

net income over

treatment 12

I 1512 3(113 1501 403 37

2 1524 3124 1600 502 46

3 1537 3259 1722 624 57

4 1969 3526 1557 459 42

5 1918 3010 1092 - 6 -(}.5

6 1922 3047 1125 27 2

7 1579 3616 2037 939 89

8 1569 3520 1951 853 78

9 1531 3131 1600 502 46

10 1463 2702 1239 141 13

II 1059 2659 1600 502 46

12 990 2088 1098

mean water applied varied from 313 to 566 mm (Table 1, col. 3) in the different ratios of drip treatments. Thus, the water saving was nil in 0.8 PE fraction to 44% in 0.4 PE.

The mean yield (Table 1, col. 2) in different treatments varied from 32 tonne / ha (t. h a - ~ ) in surface with no mulch treatment to 51 t. h a - t in treatment of drip at 0.4 PE with surface trash as mulch. Both the mulch treatments (treatment no. 10 and 11) of surface flood method yielded significantly higher than no mulch (treatment t 2). All the drip treatment either alone or in combination with either of the mulches were found to yield significantly more than treatment 12. At lower ratios (i.e 0.4 and 0.6 PE) the tomato yields were significantly more due to mulching with drip over drip alone. It is interesting to observe that when drip was coupled with the increase in PE ratio, there was a decrease in the tomato yield. The effect was the reverse when drip alone was used. Further, it is seen that with the same quantity of water used as in the flood method without mulch, there was a 44% increase in the drip-alone treatment. On the other hand, in drip with either of the mulches, the yield at 0.4 ratio was more than 55% compared to the yield obtained at 0.8 ratio of surface method. The response of tomato crop to drip either alone or with mulch was reported by earlier investigators (Grimes et al., 1976; Sanders et al., 1988; Dell, 1983; Lin et al., 1983; Bhella, 1986; Hermus, 1986; Villassar, 1986; Jadhav et al., 1990) to be better in terms of yield and water savings over conventional surface flood methods.

The effect of different treatments of weed infestation which is depicted in Table 1, col. 5, has shown that at the same level of applied water, the growth could be reduced to the tune of 76% with plastic mulching, 55% with drip alone and 27% with STM. However, a combination of drip with mulch could control the weeds even better to as high as 98%.

In a similar study (Anonymous, 1989), it was reported that black PM and STM could reduce the weed growth to the tune of 91 and 87%, respectively.

The net returns from different treatments are shown in Table 2. It can be seen that almost all treatments resulted in higher net income as compared to treatment 12, which varied from

P.K. Shrivastava et al. /Agricultural Water Management 25 (1994) 179-184 183

$1092 in drip plus PM at 0.6 PE (treatment 5) to as high as $2037.ha -~ in drip plus sugarcane trash at 0.8 PE (treatment 6). Compared to surface flood without mulch, the percentage increase in net income varied from 37 to 57 in drip alone, - 0.5 to 42 in drip plus PM, and 45.7 to 85.5 in drip plus STM. The lower percentage in PM is due to the prevailing higher cost.

4. Conclusion

The use of drip, either alone or in combination with mulching, can increase the tomato yield substantially over the normal method of irrigation, with about 44% saving in irrigation water. In the absence of drip, even mulch alone could increase the yield by about 30%. The net income could be increased by about 86% over the normal method by adopting drip along with sugarcane trash as mulch. As high as 98% weed control could be affected by the use of drip with black plastic mulching.

5. Acknowledgement

Contribution from Soil-Water Management Project, Gujarat Agricultural University, Navsari, Gujarat, India.

6. References

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I g4 P. I'i. Shriva,~t~*va ~'t ~tl ,A.~,u'i,ultnral Wat~'r Mmutt,,etm'ttt 2.5 (19~4) 17c)-/,','4

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