Soil fertility and rice productivity in shifting cultivation: impact of fallow lengths and soil amendments in Lengpui, Mizoram northeast India

An exponential increase in the human population has drastically reduced the length of the fallow period (<5 years) in shifting cultivation. This has posed the problem of weed invasion and a decrease in soil fertility and crop productivity and raised the concern of food security for the local farming communities.  The present study was conducted in two jhum fallows (FL-10 and FL-15) to find out the response of fallow length, indigenous soil microbes, and rock phosphate on soil fertility and crop productivity. The results showed greater soil physicochemical properties in FL-15 compared to FL-10. Burning significantly increased the soil pH, avail P, avail N, however, soil C, MBC and SM decreased at both the sites. Among treatments, the combined dose of rock phosphate and microbial inocula showed greater improvement in soil biochemical properties, which showed a climactic increase in crop productivity, rice yield, and soil fertility over control in all sites. Maximum rice grain yield and productivity was recorded in FL-15 followed by FL-10.This study concludes that a mixture of rock phosphate and microbial inocula from the rhizosphere soil of early regenerating plant is effective in increasing the soil fertility and crop productivity, and can be used as an important tool to sustain crop productivity and food security in the region.