The Cowpea production function in Uganda: A Cobb-Douglas approach

Abstract

Cowpea (Vigna unguiculata)is one of the important legume crops grown in Uganda, especially in the northern and castern parts of the country. Using farm data collected through a detailed diagnostic survey in four major cowpea producing districts of Uganda, a Cobb-Douglas model was used to estimate the cowpea production function, using ordinary least squares regression techniques. The returns to scale of cowpea production, marginal productivities and elasticities of the inputs used in cowpea production were estimated from the production function. From the estimated cowpea production function, land, labour and pesticides were the most significant production inputs in that order. The returns to scale of cowpea production were 1.6, 1.7,2.2 and 1.5 for Arua, Lira, Soroti and Pallisa districts respectively and were significantly different (P = 0.01). The returns to scale showed increasing returns in all cases, significant at 1% probability level of significance. The value marginal produtivities of land and capital were greater than the unit costs of these inputs. The value marginal productivities of inputs used for pest control and labour were, however, lower than the unit costs of these inputs. The findings of this study therefore indicate that, increase in cowpea production, in the short run, will generally be achieved by bringing more land under cowpea production, and in the long run, by the use of labour saving technologies such as ox-cultivation and by improving productivity, through better agronomic practices, and better technologies of pest control. Estimation of the cowpea production function at the farm level gave an insight of the most critical factors to consider in increasing cowpea production. The estimation of the returns to scale enables the analysis of the relationship between the size of the cowpea enterprise and profitability, given the available farming technology. The policy recommendations on the improvement of cowpea production given in this paper are based on the above two concepts.