Economics of Weed Management Methods as Influenced by Row-Spacing in Cowpea

Weed management is an important factor that influences the economic importance of cowpea as a cheap source of food and income for many farmers. A study was conducted to evaluate economic benefits of weed management methods used singly or in an integrated approach, and to understand the influence of row-spacing on economic benefits of weed management methods. Total variable cost of cowpea cultivation was substantially influenced by cost of weed control. A single input of hand weeding resulted in higher cost of weed control than a single input of PRE-herbicide for weed control. Increase in weed control inputs or frequency did not guarantee an increase in economic benefits. For example, removing weeds three times with hand at 3, 6 and 9 weeks after planting (WAP) during the cowpea growing season did not necessarily result in the highest yield, but rather increased the variable cost of weed control. Integrating PRE-herbicide and hand weeding for weed management resulted in the highest yield and gross profit. The lowest cost of weed control provided by using PRE-herbicide gave the highest benefit-cost ratio. The differences in economic values of weed management methods were mostly not affected by cowpea row-spacing, but generally, economic benefits of management methods decreased with increase in row-spacing. Practically, this study suggests that minimizing the use of hand weeding by complementing with PRE-herbicide for weed management could help to optimize yield, and increase profitability, particularly under a narrow row-spacing in cowpea cultivation.