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

The objective of the present study was to evaluate the effects of crop residue covers (0.0; 4.5; 9.0; 13.5 t ha(-1) millet dry matter) on water use and production of onion cultivated in no-tillage planting system (NT) as compared to conventional tillage system (CT). The study was carried out at Embrapa Hortalicas, Brazil, under the typical Savanna biome. Irrigations were performed using a sprinkle irrigation system when soil-water tension reached between 25 and 30 kPa. The experimental design was randomized blocks with three replications. Total net water depth applied to NT treatment was 19% smaller than the CT treatment, however, water savings increased to 30% for the first 30 days following seedlings transplant. Crop biomass, bulb size and yield, and rate of rotten bulbs were not significantly affected by treatments. The water productivity index increased linearly with increasing crop residue in NT conditions. Water productivity index of NT treatments with crop residue was on average 30% higher than that in the CT system (8.13 kg m(-3)).