Interaction effect of sulphur and phosphorus on growth and nutrient content of black gram (Phaseolus mungo L.)

Sulphur-phosphorus interaction has been studied in field experiments on a soil, deficient in S and medium in P with black gram (Phaseolus mungo) as the test crop. The treatments were taken in factorial combination of three levels of S (0, 30, and 60 kg ha⁻¹) and four levels of P (0, 30, 60 and 90 kg ha⁻¹) applied through gypsum (CaSO₄.2H₂O) and triple superphosphate, respectively. A uniform dose of N was applied with the treatments. The grain, straw and total dry matter yield increased with the application of S and P individually, but decreased when S and P were applied in different combinations. Sulphur application increased S and P content in seed as well as in straw. Total P content increased with applied P and decreased with S application. Applied S increased and P decreased the protein content in grains. Changes in N:S ratio in grain were affected by S and P application. The antagonistic effect of S and P fertilizers on uptake and utilization of each other was more conspicuous when both were applied together.