Dynamics of Soil Nutrient and Macro-organism Population Following Land Conversion from Fallow to cultivated Farm

An assessment of soil physical and chemical features as well as the species richness of macro-organisms was carried out in a 2-year cultivated farm, 3-year fallow,8-year fallow and a 50 –year undisturbed relic forest all located within 1 km radius within Umudike. The 3-year cultivated plot had the lowest levels of N, P, k, Ca and organic matter which were 0.14%, 2.3, 0.012, 1.6 and 0.226, respectively. The percentage sand was highest in the 3-year cultivated plot while clay % was highest in the 50 year undisturbed vegetation. The difference in textural characteristics was more pronounced between 3-year cultivated soil and the 8 year fallow than between the 8 year fallow and the 50-year undisturbed relic forest, a condition attributable to the loosening of the soil and increased run-off occurring in the 3-year cultivated farm. The abundance of soil macro-organisms increased with advance in years of fallow and it was found to be associated with increased level of organic matter and species diversity of the vegetation cover. Only species in the annelida phyla occurred in all field conditions. Keywords: Fallow, Cultivation, Nutrient status and Soil macro-organism Journal of Agriculture and Food Sciences Vol. 4 (2) 2006: pp. 93-10