LAUSR

Sands pose major challenges for efficient water and nutrient management especially for irrigated crops in monsoonal climates. We studied partial K balance in irrigated peanut crops in sandy soils in the monsoonal climate of south-central Vietnam to identify key factors of K balance that need to be managed. Four field trials were conducted in spring seasons of 2015 and 2016 at Cat Hanh and Cat Hiep communes, Phu Cat district, Binh Dinh province, Central Vietnam to evaluate the effects of rates of K application (0, 50, 75 and 100 kg ha−1) on peanut yield and partial K balance. Highest yield of peanut (average of 3.0–3.5 t ha−1) was observed with application of 75–100 kg K ha−1, however, partial K balance was negative at all application rates (− 4.4 to − 93.1 kg K ha−1). The negative partial K balance decreased with increasing K rates but was mostly attributable to the large K removal in peanut shoots (70–143 kg K ha−1) which are used for animal feed. The negative partial K balance results in depletion of soil K reserves and hence requires efficient recycling of K from peanut shoots, irrigation and fertilizer practices that minimize K leaching and regular application of K fertilizers for sustainable production of irrigated crops on sands in the tropics.