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

Abstract

An exponential increase in the human population has drastically reduced the length of fallow period (<5 years) in widely spread shifting cultivation (Jhum). This has increased the invasion of weeds and decreased soil fertility and crop productivity, and consequently raised concern of food security for the local farming communities. The present study was conducted in two jhum fallows (FL-10 and FL-15) to understand the response of fallow length and applications of indigenous soil microbes and rock phosphate on the levels of soil fertility and crop productivity. The results showed greater soil physicochemical properties in FL-15 compared to FL-10. Burning significantly increased the levels of soil pH, avail P, avail N in the soil, whereas, the same decreased the levels of soil C, MBC and SM in both the sites. Among treatments, the synergistic effect of rock phosphate and microbial inocula showed greater improvement in soil biochemical properties, and showed a climactic increase over control in crop productivity and rice yield 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 soil fertility and crop productivity, and can be used as an important tool to sustain crop productivity and food security in the region.