Precision fertigation management for cabbage (brassica oleracea var. capitata) under semi-arid tropics of maharashtra
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Date
2020-02-07
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Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani
Abstract
Water and nutrients are the basic needs of any crop. Cabbage, one of the most important vegetable crops, is very sensitive to moisture and nutrients stress. It requires comparatively more water and nutrients in precise quantity and at appropriate time. Nevertheless water scarcity and high input cost of fertilizer are the major constraints in increasing the area, production and productivity of cabbage. In order to get rid of these constraints irrigation with fertigation through drip is the most suitable option, which can save water and fertilizer in addition to increase in the area along with increasing productivity. Much of work has been done on growth and yield response of various vegetable crops under drip including scheduling. Most of the field studies were conducted with irrigation levels based on pan evaporation data. However the studies on irrigation schedule based on crop coefficient and real time evapotranspiration data and fertigation scheduling are limited. Similarly the work on vegetable crop growth simulation under various full and deficit water and fertilizer conditions are scanty. After calibration and validation, the crop growth simulation model can be used to predict the effects of drip irrigation and fertigation levels on the water requirement and the crop yield.
In view of the above points, the present experiment entitled “Precision fertigation management for cabbage (Brassica Oleracea var. Capitata) under semi-arid tropics of Maharashtra” was conducted during 2016-2017 and 2017-2018 to investigate the response of cabbage for varying irrigation schedules and fertigation levels during the winter season at AICRP on Water Management, VNMKV, Parbhani.
The experimental design was split plot with five irrigation schedules (0.4, 0.6, 0.8, 1.0 and 1.2 ETc) as main factor and and three fertigation levels (75, 100 and 125% RDF) as sub factors. Thus fifteen treatment combinations were replicated thrice.
Initially the seedlings were prepared and six weeks old seedlings were transplanted on the experimental plots. Each plot was of 7.2 x 7.5 m with the net plot size of 6.0 x 5.85 m. A buffer strip of 1 m and 2 m was kept between two adjacent plots and within replications. The plant to plant and row to row spacing of 45 and 50 cm respectively was maintained. Drip irrigation was scheduled with five irrigation viz., I1, I2, I3, I4 and I5 at an alternate day. Drip irrigation schedules were based on crop evapotranspiration which was estimated using crop coefficient and reference crop evapotranspiration estimated by FAO- 56 Penman Monteith equation. The recommended dose of fertilizer with N:P:K as 120:60:60 kg ha-1 was used for the irrigated cabbage. The fertilizers were applied in splits through irrigation water in drip irrigated plots using venturi.
The growth parameters of cabbage viz., plant height, plant spread, number of leaves, diameter of head, volume of head and leaf area index were significantly affected by individual effects of irrigation levels and fertigation levels. In all the cases, irrigation schedule I4 (drip irrigation with 100 % ETc) was significantly superior showing better cabbage growth characters among the different irrigation levels. It is also observed that I4 was comparable with irrigation schedule I3 (drip irrigation with 80 % ETc) during both seasons and in pooled analysis. In case of fertigation levels application of fertilizers at 125 % RDF(F3) showed significantly superior growth characters of cabbage which were comparable with the growth characters when fertilizers were applied with 100 % RDF(F2 ).
The interaction effects of irrigation and fertigation levels (I x F) on growth parameters of cabbage at all growth stages were not significant during both crop seasons.
The higher weight of curd (g plant-1) and total yield (q ha-1) of cabbage can be obtained if irrigation is scheduled at 1.0 ETc or even at lower level of 0.8 ETc with saving in irrigation water. The irrigation level above 1.0 ETc is found to decrease the curd yields.
The treatment combination of 1.0 ETc with 125% RDF, 1.0 ETc with 100% RDF and 0.8 ETc with 100% RDF give comparable and better cabbage yields. Hence the combination treatment of drip irrigation at 0.8 ETc and fertilizer level of 100% RDF may be adopted to obtain higher yields with net saving in water and fertilizers. The economic analysis of cabbage under drip fertigation also suggests that the drip irrigation at 0.8 ETc and fertilizer level of 100% RDF is more economical and feasible as compared to all other combinations.
The treatment combination of 1.0 ETc with 125% RDF, 1.0 ETc with 100% RDF and 0.8 ETc with 100% RDF give comparable and better cabbage yields. Hence the combination treatment of drip irrigation at 0.8 ETc and fertilizer level of 100% RDF may be adopted to obtain higher yields with net saving in water and fertilizers. The economic analysis of cabbage under drip fertigation also suggests that the drip irrigation at 0.8 ETc and fertilizer level of 100% RDF is more economical and feasible as compared to all other combinations. The soil moisture distribution indicates that the moisture content is higher in the upper 0-15 cm soil layer than the lower 15-30 cm layer. The soil moisture content decreases horizontally as it moves away from the emitter.
AquaCrop model can predict the temporal variation in soil moisture distribution and total water requirement of cabbage reasonably well. AquaCrop model can favourably simulate the effect of full water and deficit irrigation on cabbage crop growth parameters. The differences between observed and simulated yields are within the acceptable limits.