EFFECTS OF PENTAD DRY SPELLS ON THE YIELD OF SOME CROPS IN THE SEMI-ARID ECO-CLIMATIC REGION OF NORTHERN NIGERIA.

B.A.Sawa and A. A. Adebayo

This paper examines the impact of pentad dry spells on the yield of maize, millet, sorghum, groundnuts and cowpea in the semi arid region of northern Nigeria using daily rainfall data from 1960 to 2009 and crop yield per hectare for 4 synoptic stations. Bivariate Correlation Analysis was used to deduce the statistical relationship between occurrence of pentad dry spells and the yield of the crops. Stepwise Multiple Regression was used to isolate dry spell parameters that are critical to crop yield in the region. Results obtained show that occurrence of pentad dry spells in all the months and total dry spells have significant effect on the yield of sorghum and groundnuts. Maize yield showed a significant relationship with 1 and 2 pentads as well as total dry days. While only total dry spells show a significant relationship with the yield of millet. Maize shows more sensitivity to dry spells than the other crops and millet showed more resistance to dry spells than the other crops. Two dry spell parameters (10-day dry spells in August and total dry spells during the growing season) were identified as being critical to the yield of the crops in the area. These two factors jointly accounted for about 74.1%, 21.5%, 52.9%, 51.4% and 40.1% of the variations in the yields of the crops respectively in the region.

Key words: Bivariate Analysis, Coefficient of Determination, Drought, Dry Spells, Pentads, Stepwise Regression.