Effect of continuous cropping and integrated nutrient management practices on soil properties and yield of rice (Oryza sativa)rice cropping system in acid soil

The long-term effects of inorganic alone and combine effect of inorganic as well as organic sources of nutrients on soil fertility and crop productivity were investigated in rice (Oryza sativa L.)rice cropping sequence in acid soils of north-east India from 1987 to 2014. The higher average grain (6.50 t/ha) and straw (8.25 t/ha) yields of the rice rice sequence were recorded in case of 75% recommended nitrogen, phosphorus, and potassium (NPK) through fertilizers along with 25%N through incorporation of crop stubbles in winter rice at the time of puddling and 75% recommended NPK through fertilizers in autumn rice. The higher available N, P and K status of soil were recorded when recommended 50% NPK through chemical fertilizers applied along with 50%N through Azolla in winter rice and 100% recommended dose of NPK through chemical fertilizers to autumn rice. However, uptake of NPK by ricerice sequence was higher when 75% recommended NPK dose was applied through chemical fertilizers to both winter and autumn rice along with 25%N through crop stubbles only in case of winter rice. Thus, integrated nutrient management involving organic and inorganic sources not only increases the availability and uptake of ma- jor nutrients but also helps in yield sustainability in ricerice cropping system under long run in acid soils.