Short-term effects of conservation agriculture practices on soil quality under rice-wheat cropping system
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Date
2021-02
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Sher-e-Kashmir University of Agricultural Sciences and Technology Jammu, J&K
Abstract
Intensive tillage, removal or burning of crop residues, limited organic manure use, declining irrigation water resources are the major causes of soil degradation and unsustainability of rice (Oryza sativa L.)-wheat (Triticum aestivum L.) system (RWS) in South Asia. Present investigation on “Short-term effects of conservation agriculture practices on soil quality under rice-wheat cropping system” was carried out at research farm, Chatha, SKAUST-Jammu. The objectives of the study were to evaluate the effect of CA on yield and soil quality with special reference to the carbon dynamics in soil. The experiment was established in 2015 in a factorial RBD plot design with three replications. The two factors under this experiment were conservation agriculture (CA) and weed management practices (WM). Under the CA, five levels were conventional agriculture (CTR-CTW), partial CA1 (CTR-ZTW-ZTG), partial CA2 (CTDSR-CTW-ZTG), full CA1 (ZTDSR-ZTW+R-ZTG) and full CA2 (ZTDSR+R-ZTW+R+ZTG). The three levels for weed management were chemical herbicide, integrated weed management and weedy check. The results showed that full CA2 treatment resulted in reduced subsurface compaction, increased hydraulic properties (saturated hydraulic conductivity and infiltration ) and improved soil aggregation ( MWD and GMD) as compared to conventional agriculture. Available nitrogen, phosphorus, potassium and DTPA-Zn in surface soil layer under full CA 2 were significantly higher by 13.5, 51.2, 55.6 and 14.4 per cent, respectively over that under conventional agriculture treatment at the end of four year of continuous crop cycles whereas, lower values DTPA-Zn and Mn were reported under CA treatments as compared to those in conventional agriculture. The biological indicators i.e. dehydrogenase, alkaline phosphatase, MBN and bacterial and fungal count under full CA2 were significantly higher by 104.3, 40.6, 32.1, 31.3 and 31.9 per cent, respectively over that under conventional agriculture treatment. As compared to conventional agriculture practice, adoption of full CA2 resulted in significantly higher carbon fractions such as KMNO4-C, MBC, POC and WSOC in the surface soil layer, however the effect of CA on total soil organic carbon was not significant. The carbon management index (CMI) of surface soil layer under full CA 2 treatment was 48.9, 25.3, 24.8 and 8.0 per cent higher than that under conventional agriculture, partial CA1, partial CA2 and full CA 1, respectively after 4 years of experiment. The highest rice grain yield (4.09 and 4.12 t ha-1 for 3rd and 4th year of experiment) was reported under conventional agriculture and highest wheat grain yield was observed under full CA2 treatment (4.27 and 4.26 t ha-1 for 3rd and 4th year). The impact of CA was significant and it was limited only to surface layer for most of the soil parameters, however, in subsurface layers CA practices did not significantly influenced soil properties. The weed management practices did not influenced the soil physical, chemical and biological properties. Overall, the adoption of CA practices improved the physical, chemical and biological health of soil. Principal component analysis (PCA) identified MBC, bulk density, pH and TOC as the most sensitive indicators for assessing soil quality. Highest SQI (0.91) was reported under full CA2, whereas conventional agriculture resulted in lowest SQI (0.68). The present study provided reliable physical, chemical and biological indicators to monitor soil quality changes in response to conservation agriculture practices in rice-wheat cropping system.
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preferred for your work_Singh, G. 2021. Short-Term Effects of Conservation agriculture practices on soil quality under rice-wheat cropping system. Ph. D. Thesis, Sher-e- Kashmir University of Agricultural Sciences and Technology of Jammu.