Dynamics of soil nutrients and microbial biomass during first year cropping in an 8-year jhum cycle
2002
Arunachalam, A.
The soil nutrient status and microbial biomass at three stages of first year cropping in an 8-year jhum (slash-and-burn agriculture) cycle system were determined and compared to an adjacent humid tropical forest in Arunachal Pradesh, north-eastern India. Soil pH increased after burning and decreased as the cultivation progressed in the jhum field. Soil organic carbon, available-P,total Kjeldahl nitrogen, ammonium-N and nitrate-N decreased as the duration of cultivation increased. Microbial biomass C, N, and P were high in the forest stand. Microbial biomass C increased gradually as cultivation progressed, while microbial biomass N and P showed a post-burn decreasing trend. Bacterial and fungal populations were drastically reduced following slash burning. The study indicates that first-year cropping may result in temporary pattern homogenization of soil nutrient cycling, but can have drastic effects with continued slashing and burning for long-term agriculture.
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