Sharma, SandeepSwarnjeet Singh2018-09-182018-09-182018http://krishikosh.egranth.ac.in/handle/1/5810073717The sustainability of rice-wheat system (RWS) is at threat due to the deterioration of soil health and emerging of new challenges of climate change caused by continuous burning of huge amounts of crop residue. The current study evaluated the effect of N application and rice straw incorporation after 7 year (2010-17) on soil enzyme activities, labile carbon pools and chemical properties in rhizosphere and bulk soils at maximum tillering (MT) and flowering (FL) stage of wheat under RWS. Four main-plot treatments of N application were 0, 90, 120 and 150 kg N ha-1 and four sub-plot treatments of rice straw incorporation were 0, 5, 7.5 and 10 t ha-1. The results showed that 120 kg N ha-1 and rice straw incorporation (7.5 and 10 t ha-1) significantly increased all the soil biochemical properties (enzyme activities, labile carbon pools and chemical properties) except pH and EC. Maximum wheat grain yield observed with application of 120 kg N ha-1 and 7.5 t ha-1 rice straw incorporation. The majority of soil enzyme activities and labile carbon pools were higher in rhizosphere than bulk soil. The enzymatic activities and quantity of carbon pools were 5% and 15% higher at MT as compared to FL stage of wheat. Soil enzyme activities were positively and significantly correlated with labile carbon pools. Principal component analysis (PCs) identified β-glucosidase, L-asparaginase, total carbohydrate carbon and total polysaccharide carbon as most sensitive indicators for assessing soil quality under rice straw incorporated RWS.ennullThesis