Singh, R. C.Kumar, Murari2017-07-052017-07-052016http://krishikosh.egranth.ac.in/handle/1/5810024366The soil has its own inherent capacity to supply nutrient to the crops but due to intensive cultivation of high yielding varieties of crop with modern technologies, the nutrient supplying capacity of soil is gradually declining over time. Therefore an experiment was conducted from 2011 at the Bihar Agricultural College farm, Sabour, Bihar in a split plot design which include three main plots of different rice establishment techniques viz. zero tillage (ZT), permanent bed (PB), and conventional tillage (CT) and subplot treatments comprising rice crop of three different cropping systems viz. rice-wheat (R-W), rice-maize (R-M), and rice-lentil (R-L) which were evaluated for impact of conservation agriculture on potassium pool under rice crop. Under all tillage practices, different fractions were found in the order: Total K> Non Exch-K > Exch-K > Avail- K >Water soluble-K. Range of recorded Water soluble K was (12.24-19.83 ppm), Available K (144.80-196 ppm), Exchangeable K (632.46-862.46ppm), Non-exchangeable K (1357.87-2874.68ppm) and Total K (31137-55894.10 ppm). In all the treatments, Soil pH, Organic carbon, Saturation capacity and different fractions were found higher in surface layer compared to subsurface layer. Soil pH was significantly and positively correlated with OC (r=0.559**), WS-K (r=0.426**), Avail-K (r=0.730**), Exch-K (r=0.594**) and total K (r=0.412**). EC was found negatively and significantly correlated with soil saturation % (r= -0.445**) while OC was positively correlated with soil saturation % (r=0.584**), WS-K (r=0.593**) and Avail-K (r=0.727**). Saturation capacity was positively correlated with WS-K (r=0.562**), Avail-K (r=0.589**) and non-Exch K (r=0.103**). WS-K was found positively correlated with Avail-K (r=0.562*). Avail-K was positively correlated with Exch-K (r=0.45*) and Exch-K was positively correlated with non-Exch-K (r=0.494*) and total k (r=0.58). Similarly, Non Exch-K was found positively correlated with total-k (r=0.636*). MWD was found positively correlated with Non Exch-K and Total K. and negatively correlated with Avail-K and Exch-K. Multiple regression analysis indicates that that 77% of available Potassium is determined by pH, EC, OC, saturation capacity, and other forms of potassium whereas 60 % of MWD (aggregate index) was determined by water soluble, available, exchangeable and total pool of potassium. The highest grain and straw yield was recorded under conventional puddled method which was significantly higher to the grain yield obtained from permanent bed and statistically at par with zero tillage. The highest grain and straw yield was recorded in rice-lentil cropping system which was significantly higher than grain yield obtained from rice-wheat and rice-maize cropping system.ennullThesis