Abstract

A field experiment was conducted to study the effect of graded levels of N as urea alone and in combination with KCL, CaSO4 and ZnSO4 on rice yield, uptake of N. N use efficiency and N transformations in Madurai. The inorganic salts and graded levels of N addition positively influenced the inorganic fractions of N and available N in soil at all stages of crop growth. Increased grain production was noted for application of inorganic salts with urea. The increases was about 8% for KCL, 4% for CaSO4 and 3 per cent ZnSO4 over urea alone. The N uptake by rice increased with graded levels of N application. Addition of inorganic salts particularly KCL increased the N uptake followed by urea + CaSOs and urea +ZnSO4. The N uptake by the crop was found to be correlated with soil inorganic N fractions and available N at all stages of crop growth.

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