Effect of manuring and fertilizer on micronutrient uptake by rice under Rice-wheat system

The effects of conjunctive use of farm yard manure (FYM), green manure (GM), crop residues incorporation in the form of wheat cut straw (WCS) and inorganic fertilizers on the availability and uptake micronutrients in rice-wheat system were investigated in a long term experiment conducted at experimental farm of Punjab Agricultural University, Ludhiana. GM resulted in significantly higher Zn content of the soil (2.53–2.65 mg kg⁻¹) followed by FYM (2.24–2.59 mg kg⁻¹) and WCS (2.12–2.19 mg kg⁻¹), Whereas, Cu content increased significantly in the organic manured plots (1.35–1.66 mg kg⁻¹ soil). The maximum DTPA-extractable Fe content (23.19 mg kg⁻¹) was resulted with the application of 50 per cent of recommended N through FYM. The application of 100 per cent recommended N + 50% N through FYM application; 50 per cent recommended N + 50% N through FYM application and 75 per cent recommended N + 25% N through FYM application registered 27.4, 21.2 and 18.6 per cent higher DTPA-extractable Mn over the application of 100 per cent of the recommended NPK dose. The significantly highest uptake of Zn, Cu, Fe and Mn was recorded in treatments 75 per cent recommended N + 25% N through GM application (864.8 g ha⁻¹); 50 per cent recommended N + 50% N through GM application (153.9 g ha⁻¹); 100 per cent recommended N + 50% N through FYM application [(1319.1 g ha⁻¹ (Fe) and 1679.3 g ha⁻¹ (Mn)], respectively where nitrogen substitutions through FYM and GM were done. The substitution of 25 and 50 per cent N through GM along with chemical fertilizers gave 6.05 and 4.01 percent higher yield than recommended level of fertilizers (56.89 qha⁻¹).