Improving Irrigation, Potassium and Sulphur Use Efficiency of Peanut (Arachis hypogaea) in Tropical Sandy Soils

Increasing the productivity of irrigated crops on low fertility sands depends on jointly improving water and nutrient use efficiencies. The aim of this study was to investigate the hypothesis that improved water scheduling and delivery would increase K and S use efficiency of irrigated peanut crops on deep sands. Factorial experiments (irrigation management and K, S rates) were conducted on two deep sands in Binh Dinh province, South Central Coastal Vietnam (SCV). Peanut yield increased 17% in response to switching from the farmers' irrigation practice (FI) to sprinkler irrigation scheduled according to evaporation rates (ER), combined with increasing fertilizer K and S from 50 kg K ha(-1) + 20 kg S ha(-1) to 75 kg K ha(-1) + 30 kg S ha(-1). Nutrient loss with ER relative to FI decreased by 52-64% for K and by 20-24% for S. The irrigation water use efficiency of peanut (kg pod kL(-1) of water) increased by 44% under the ER approach. Integrated water and nutrient management practices substantially improved use efficiency of K and S fertiliser, achieved substantial irrigation water savings and increased profits for peanut on infertile deep sands.