Response of irrigated maize to urea-ammonium nitrate and ammonium thiosulphate solutions on a sulphur deficient soil

Ammonium thiosulphate solution, (ATS, (NH₄)₂S₂O₃, 12% NH₄-N and 26% S), is a nitrogen-sulphur fertiliser which can also inhibit nitrification, inhibit area hydrolysis and also solubilize micronutrients in alkaline soils. A three year field study was conducted in northeastern Italy to compare the growth, yield, and nutrient uptake of irrigated maize (Zea mays L.) fertilised with 250 kg N ha^-1 urea-ammonium nitrate solution (UAN, 30-0-0) or UAN plus ATS. Dry matter (DM) yield, sulphur (S) and nitrogen (N) uptake were measured at several growth stages. Grain was measured and analyzed at maturity. Maize grain yield and N uptake were increased respectively 30.6% and 42.2% in the first year by adding ATS to UAN. Adding 10% by weight ATS to UAN (22.8 kg S ha^-1) increased grain yields by 1.9, 1.7 and 1.6t ha^-1 for the three years of the study. To distinguish whether the response was due to S or other ATS attributes, ATS was compared to an equivalent amount of S from single superphosphate (SSP). Plots fertilised with ATS gave grain yields 0.5 and 1.2 t ha^-1 greater than plots fertilised with equal rates of S from SSP in the last two years of the study. This added yield from ATS over SSP may have been due to beneficial effects of ATS on N or micronutrient availability or to the split application of the S from ATS.