Study of Nitrate-Sulphate Interaction on the Growth and Nutrient Uptake by Maize Using ³⁵S

In a pot culture experiment, application of N or S alone increased dry matter production, N and S content in plant and their total removal per pot. A positive significant interaction was found between N and S; with increase in level of S from 0 to 20 ppm in presence of various N levels, total removal of N and S, utilization of fertilizer S and fraction of S in the plant derived from the fertilizer increased, and a combined application of 90 ppm N and 20 ppm S produced the maximum effect. In presence of S, increasing level of N from 0 to 30 ppm enhanced the fraction of S in the plant from soil native source and this effect was lost with 60 and 90 ppm N. The critical limit of N:S ratio in leaves and stem for yield response was 16:1 or below.