![]() KeywordsĪndo K (2014) Dynamics of soil organic matter under slash-and-burn agriculture in a semiarid woodland of Zambia. Therefore, SOM will not decrease drastically under short cropping and short fallow rotation because recent decrease in emergent trees and increase in bush trees brought small loss of SOM during burning. However, in the semiarid region, the decrease in soil C and N stock during cropping was small with return of plant residue because long dry season constrains loss of SOM through leaching and decomposition and N 2 fixation by free-living N 2 fixation. In other regions such as Central Africa, Southeast Asia, and South America, soil C and N stock decreased rapidly even during short cropping, while grain yield was higher than this semiarid region. Thus, under rainfed agriculture without fertilizer in semiarid region, this type of slash and burn was relatively suitable to maintain grain yield and SOM contents although the yield and the SOM were low level compared to other regions where slash and burn is practiced. The C and N stock could not be fully recovered, especially burned spots. ![]() (3) Without burning, 2-year fallow after 3-year cropping is relatively useful management in terms of maintenance of POM, SOM, and grain yield, although woody biomass decreased compared to 2-year fallow after 1-year cropping. (2) At spots burned with emergent and bush trees, SOM decreased only by burning and could be restored during short cropping, although N contents of SOM and woody biomass were not restored even during fallow. The results of our field study indicated the following: (1) More than 10-year cropping exhausted SOM and woody biomass SOM and woody biomass were not restored during short fallow. It is, therefore, important to elucidate the effect of the conversion to cropland and shortened fallow period on SOM for evaluation and improvement of soil fertility. Soil organic matter (SOM) is important to sustain crop productivity for famers in semiarid tropics of Africa who use little fertilizer and rely on the nutrient released from SOM.
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