Effect of Burning and Cultivation on Soil Properties and Microbial Population of Four Different Land Use Systems in Abakaliki.

Measurement of the effect of burning and cultivation on soil prosperities and microbial population of four different land use systems - forest land, bush fallow systems, continuous cropping land and alley cropping system in Abakaliki was carried out in a complete randomized design (CRD). Burning improved soil pH from strongly acid to moderately acid in the bush fallow system and slightly acid (pH 6.1) in the alley cropping system but reduced organic C by 36% in the forest land, 44% in both the bush fallow and continuous copping land 34% in the alley cropping system. Also total soil N declined in all the land use systems. Available P, exchangeable Ca, Mg and K increased after burning. Cultivation inversely depleted nutrient level with the lowest soil nutrient content occurring in the continuous cropping land. Burning did not have lasting effect on the microbial populations. At 5 days post-burn, the population of micro organisms were very low compared to the pre-burn populations. But at 25 days post-burn there was a surge in microbial population. In the bush fallow and alley cropping systems, both bacteria and the cellulolytic groups increased in numbers but in the strongly acid forest and continuous cropping land the population of fungi dominated. Continuous cultivation led to a decrease in the population of bacteria, actinomycetes and algae. The general decline in the population of microorganisms under cultivation was associated with the over all fertility decline of cultivated soil.