Optimizing tillage and irrigation for sunflower cultivation in rice fallow alfisols of semiarid tropics

Abstract

SUMMARY Studies were conducted on sandy clay loam soil (Typic Haplustalf) to evaluate the effect of five different tillage practices versus four irrigation regimes, 60 mm irrigation at IW/CPE=0.6, 0.8, 1.0 and 1.2, and their interaction on soil physical changes and performance of sunflower (Helianthus annuus L.) under rice fallow condition. Tillage in general had more positive effect on seedling emergence, growth and yield of sunflower than zero tillage in puddle rice fallows. Deep primary tillage with tractor-drawn disc plow or MB plow produced significantly larger heads with higher test weight, however, secondary tillage with rotavator, either power-tiller- or tractor-drawn, made finer tilth and recorded significantly higher seedling emergence (80.7%). Tillage with tractor-drawn disc plow + rotavator (deep-fine tillage) gave significantly higher mean seed yield (1311 kg ha -1 ) over tractor-drawn MB plow + tractor-drawn cultivator - deep tillage (1172 kg ha -1 ), ox-drawn desi plow + power-tiller-operated rotavator – shallow fine tillage (1054 kg ha -1 ) and ox-drawn desi plow + ox-drawn cultivator - shallow tillage (931 kg ha -1 ). The irrigation regime at IW/ CPE=1.2 recorded higher seed yield than IW/CPE=0.6, 0.8 and 1.0. Water use (ETa) by sunflower increased with increase in intensity of tillage and irrigation. WUE was higher in deep tillage practices and in irrigation regime of IW/ CPE=0.8. Deep tillage, besides saving 18% of irrigation water, resulted in about 24% higher sunflower seed yield compared with shallow tillage. Interaction effects revealed that significantly higher sunflower growth and yields (both seed and oil) was realized when tillage was done with tractor-drawn disc plow + rotovator coupled with scheduling irrigations at IW/CPE=1.0 or 1.2. Tillage with two passages of country plow + once with power-tiller-operated rotavator and scheduling irrigation at IW/CPE=1.2 produced significantly superior yields of sunflower than farmers’ practice.