Author(s):

RK Naresh, PC Jat, Vineet Kumar, SP Singh and Yogesh Kumar

Abstract: Soil organic carbon plays the crucial role in maintaining soil quality. The impact carbon and nitrogen dynamics and rate of SOC sequestration in tillage and crop residue application is still in investigation in this environment. A field experiment was initiated in 2009-10 and continued up to 2015-16 to compare the organic carbon build up in the soil due to tillage and crop residue application. The soil organic carbon data represents the cumulative after five crop cycle. About 5 t ha^-1 of standing rice and wheat crop was retained for succeeding crop in retained treatments. Result showed that, soil organic carbon build up was affected significantly by tillage and residue level in upper depth of 0-15 cm but not in lower depth of 15-30 cm. Higher SOC content of 19.44 g kg^-1 of soil was found in zero tilled residue retained plots followed by 18.53 g kg^-1 in permanently raised bed with residue retained plots. Whereas, the lowest level of SOC content of 15.86 g kg^-1 of soil were found in puddled transplanted rice followed by wheat planted under conventionally tilled plots. Zero tilled residue retained plots sequestrated 0.91gkg^-1yr^-1 SOC in the year 2015-16 which was 22.63% higher over the conventionally tilled residue removed plots after seven seasons of experimentation. The zero tilled soil had values of dehydrogenase, urease, phosphatase and β-glucosidase activities, and water aggregate stability higher than conventional tilled soils but lowers than the soil under permanent raised beds with residue retention. The enzyme activities and water aggregate stability reflected early changes in soil the profile to a greater extent than did physical-chemical and chemical properties. Similarly, treatments that included organic manure had significantly higher SOC concentrations and stocks than mineral or unfertilized treatments. The organic manure treatments also had higher concentrations of non-labile but at the same time a higher proportion of labile C than the mineral or unfertilized treatments. This was confirmed by the carbon management index (CMI) which was significantly increased by organic manure addition. This study demonstrates that fertilization strategies that include organic manure can increase the pool of stable C in the surface soil layer, while at the same time increasing concentrations and proportions of labile C.Therefore, CA in rice-wheat system can help directly in building–up of soil organic carbon and improve the fertility status of soil.

Pages: 723-740  |  1471 Views  392 Downloads

Download (1263KB)