LAUSR

ABSTRACT Sands have favourable physical properties for harvesting peanut, but improving S and water use efficiency on these soils remains a challenge. We studied partial S balance in irrigated peanut crops on sands of Central Vietnam to identify key factors of S fertiliser management affecting S inputs and outputs. Field trials were conducted in the spring seasons of 2015 and 2016 to determine the effects of S application rates (0, 15, 30, 45 kg ha−1) on peanut yield and partial S balance. Sulfur balances were negative (−28.3 to 5.6 kg S ha−1) at rates < 30 kg S ha−1, while at higher rates of S fertiliser application that produced maximum pod yield (30–45 kg S ha−1), three of four sites showed neutral to slightly positive S balance (1.5–5.6 kg S ha−1). The negative partial S balance decreased with increasing S rates but was mostly attributable to the large S removal in peanut shoots (9.7–22.3 kg S ha−1) which are used on farms for animal feed. The negative partial S balance results in depletion of soil S reserves and hence efficient recycling of S on farms is critical for sustainable crop production on sands of VN.