An Analysis of the Impacts of Rainfall Variability and Crop Zones Classification for the Federal Capital Territory, Nigeria

Abstract

This study aims at analysing agro-climatological parameters and establishing a link between certain selected agro-climatological indices and the sustainability of agricultural production in the Federal Capital Territory (FCT). Two sets of data, climatic and crop yield data were collected and subjected to various agro-climatological analyses. Agro-climatological analyses include the derivation of onset, cessation and Length of rainy season (LRS), seasonality index, drought index and precipitation periodicity index. The statistical analyses include monthly and annual means, and deviation from the mean trend line. The result of moisture index in line with crops optimum moisture requirement was used to classify the territory into agro-climatic zones for crop production. The result of the climatic indices revealed that although rainfall has declined throughout the study period, the results from other derived rainfall parameters showed that the region has done well in terms of crop yield. Temperature and humidity levels have increased during the study period owing not just to global warming alone but also to some anthropogenic activities, particularly deforestation through the activities of using wood as a fuel and the charcoal business within the territory. The uniqueness of the rainfall pattern was very clear (increasing from south to north). Another important feature is the division of the region into two climatic zones by the PP Index. The result in the characterisation of the territory into crop-ecological zones revealed three ecological zones whose rainfall is zonal in orientation: (1) the southern humid zone, (2) the mid-central sub humid zone, and (3) the north-eastern humid zone. It is therefore recommended that further studies be carried out on trends of agro-climatic conditions in the study area.