Enhancing soil nutrient dynamics and productivity of Basmati rice through residue incorporation and zinc fertilization

Field experiments were conducted to evaluate the effects of summer green manuring crops (SGMCs) and zinc (Zn) fertilization on soil biological properties, nutrient dynamics and productivity of Basmati rice, during summer-rainy (kharif, April-November) seasons of 2008 and 2009 at the research farm of the Indian Agricultural Research Institute, New Delhi. Among the SGMCs, Sesbania aculeata added the highest crop residue, i.e. 38.56 t ha(-1) leading to recycling of 180.5, 22.6 and 267.8 kg N, P, K ha(-1) (mean of 2 years). Incorporation of S. aculeata also led to a significant increase in the succeeding Basmati rice grain yield which was 2.38%, 4.14%, and 10.82% higher over cowpea, mungbean and summer fallow, respectively. Among the different sources, levels and methods of Zn application, application of 2.0% Zn-enriched urea (ZEU) as ZnSO4 center dot H2O was found to be best with respect to total uptake of N, P. K and Zn by rice and also soil biological properties, especially enhanced alkaline phosphatase, dehydrogenase, fluorescein diacetate activities and microbial biomass C. Application of 2.0% ZEU as ZnSO4 center dot H2O recorded the highest Basmati rice grain yield, i.e. 3.79 t ha(-1) and the increase was registered to the tune of 12.78%, 2.43%, 3.26%, 5.71%, 7.05% and 5.27% over control (only N), 2.0% ZEU as ZnO, 5 kg Zn ha(-1) as ZnSO4 center dot H2O, 5 kg Zn ha(-1) as ZnO, 0.5 kg Zn as ZnO slurry and 1.0 kg Zn through 0.2% foliar spray, respectively. Our results clearly indicated that incorporation of S. aculeata SGMC residue in conjunction with 2% ZEU as ZnSO4 center dot H2O significantly enhanced soil microbial activities, which are vital for the nutrient turnover and long-term productivity of soil, leading to enhanced productivity of Basmati rice. (C) 2012 Elsevier B.V. All rights reserved.