Effect of dates and methods of winter rice (Oryza sativa L.) transplanting on relayed niger (Guizotia abyssinica) and soil health

A field experiment was conducted to study the effect of dates of transplanting under different methods of cultivation on productivity of winter rice (Oryza sativa L.) and their effect on rice-niger (Guizotia abyssinica) relay system at Regional Agricultural Research Station, Shillongani Nagaon, Assam during kharif-rabi seasons in the year 2014-15 and 2015-16.  Rice transplanted on 20 June recorded significantly higher yield attributes and grain yield of rice (59.19 q/ha) as compared to the later dates of transplanting, and it was followed by 5 July- transplanted rice. Transplanting on 20 June resulted in higher values in respect of yield attributes, yield of relayed niger, rice equivalent yield (REY) of rice- niger relay system (75.68 q/ha), NPK uptake by rice and niger as well as soil fungal and bacterial population after harvest of rice and niger. System of Rice Intensification (SRI) recorded significantly higher value of yield attributes and grain yield of rice (60.34q/ha) as compared to conventional method. In case of relayed niger, yield attributes, seed yield and REY were found higher under SRI method of rice cultivation. Under SRI method, higher uptake of NPK by rice and niger and higher soil fungal and bacterial populations after harvest of rice and niger were observed as compared to conventional method. However, conventional method of rice cultivation recorded significantly higher values of soil available N, P₂O₅ and K₂O content at the end of two year-crop cycle over that of SRI.