Assessing soil biological properties and nutrient availability after long term crop residue management in rice-wheat cropping system
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Date
2019
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Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur
Abstract
Organic sources for crop production hold a great promise due to their local availability, as it can improve physical, chemical and biological parameters of soil. Hence in a long-term experiment with crop residue managements and Zn applications in rice-wheat cropping system the objectives were to study: changes in biological properties of the soil during rice growth period, nutrient availabilities of soil, and rice yield, growth attributes and nutrient uptake. During kharif, 1994 in a Zn-deficient calcareous soil at Dr. Rajendra Prasad Central Agricultural University, Pusa farm in split-plot design with four crop residue levels in main plots and four Zn levels in sub-plots under rice-wheat cropping system. As per treatments crop residues of previous crops were incorporated in each season whereas Zn was applied at the time of start of the experiment as starter dose and again applied after 25 years. Among the different treatment combinations, soil organic carbon varied between 5.10 mg kg-1 in the crop residue and Zn control to 7.19 mg kg-1 in crop residue management at 100% and Zn level of 10 kg ha-1 plot. Crop residue management at 25, 50 and 100% levels has significantly improved soil organic carbon, and decreased soil bulk density, free CaCO3 and penetration resistance. Soil active carbon, respiration microbial biomass
carbon and autoclave citrate extractable protein are significantly influenced by all the levels of crop residue. Soil active carbon, microbial biomass carbon and autoclave citrate extractable are highest at 60 days after transplanting of rice whereas the concentration of soil respiration was highest at 90 DAT. Among the soil biological properties highest increase was found in soil respiration followed by autoclave citrate extractable protein during rice growth period. Crop residue at 50 and 100% influences soil available Zn, Fe, Mn, N and K and their uptake by rice. Crop residue at different levels influenced all the yield and growth parameters whereas Zn application at 7.5 and 10 kg ha-1 rates also had significant increase in rice grain yield as compared to Zn control plot.