Microbial succession and changes in carbon and nitrogen during decomposition of leaf litters of Tephrosia candida (Roxb.) DC. and Oryza sativa L. under shifting cultivation in Mizoram, northeast India

Abstract

The present study aims to understand microbial succession and dynamics of dry matter, carbon and nitrogen during the decomposition of leaf litters of Tephrosia candida (Roxb.) DC. and Oryza sativa L. in two fallow lands (FL) of 3 years (FL-3) and 8 years (FL-8) following shifting cultivation in Mizoram. A total of 64 microorganisms were isolated from two leaf litters by serial dilution method, out of which 13 microbes were identified as decomposers as they exhibited a positive response towards the enzyme activity. Among these 13 microorganisms, 4 (SKT 02, SKT 05, SKT 09 and SKT 020) were bacteria (Streptobacillus sp. and Bacillus sp.), 5 (SKT 033, SKT 034, SKT 035, SKT 040 and SKT045) were fungi (Microsporum sp., Rhizopus sp. and Aspergillus sp.) and 4 (SKT 030, SKT 052, SKT 053 and SKT 060) were actinomycetes (Streptomycetes sp.). T. candida leaf litter possessed low initial Carbon/Nitrogen (8.77) and Lignin/Nitrogen ratio (2.29) and considered a high-quality resource exhibiting higher decomposition rate. Mass loss of carbon and nitrogen (~ 40-80%) was maximum during the initial two months, which slowed down in the later period of decomposition. It was concluded that the number of bacteria, fungi and actinomycetes regulate organic matter and nutrient dynamics in the soil through various enzymatic actions on high- and low-quality litters. The combination of O. sativa and T. candida litter is recommended to manage soil fertility in shifting cultivation of Mizoram,Northeast India.