Effects of the Timing and the Number of Sprays on Cotton Yields in Sind: An Exploratory Analysis

Abstract

Plant protection measures for a weather-sensitive crop like cotton can make a difference between its actual and normal yields. Since in the cotton-growing areas of Pakistan, small variations are observed in the use of complementary inputs like fertilizer, seeds, irrigation and cultural practices, the timing of application and the quality and amount of pesticides assume crucial importance in determining cotton yields, In Pakistan, quality data relating to pesticide use are almost non-existent because of the absence of organized and coordinated research on pest management. As a result, it is very difficult, if not impossible, to test models of pest-crop environment and to derive optimal pesticide dosage response, incorporating pest damage and pest kill functions. Furthermore, a survey of literature available in Pakistan reveals that whereas studies under controlled experiments on the biological aspects of the use of pesticide have been frequent [I; 2; 3; 4}, few studies exist on the economics of pesticide applications as observed from the farmer's land. This paper, therefore, adopts an exploratory method for assessing the usefulness of the application of pesticide to cotton crop in Sind.• By applying simple statistical techniques to farm level data, we try to answer some key questions. Is the timing or number of sprays more important in explaining the variation in yields? Is the interaction of these two factors a significant source of explained variation?