Cost-Benefit Implications of Conservation Agriculture with Trees in the Dry Lands of Machakos County, Kenya

The adoption of conservation agriculture and agroforestry has been cited as the solution to the degradation and low profitability challenges in the drylands. The two systems have been known to result in high profitability through the improvement of yields and lowering of crop production costs. The study was carried out as part of ongoing experimentation established in the short rains (SR) season of 2012 by the World Agroforestry Centre in an on-station site at the Agricultural Training Centre (ATC) in Machakos County, Kenya. The trials were based on a split plot arranged in a randomised complete block design with two farming systems (conventional and conservation agriculture) serving as the main blocks, 10 treatments and three replicates, summing to a total of 60 plots. In the fields, three shrub species (Calliandra calothyrsus Meissn., Cajanas cajan (Pigeon pea), and Gliricidia sepium Jacq.) were planted in three different spacing (1.5 x 1 m, 3 x 1 m, 4.5 x 1 m) for maize-legume intercrops. The costs of production were recorded consistently in each season (LR 13, SR 13, and LR14). The maize and legume yields were valued at the market selling price from the local market, and a cost-benefit analysis was done through the calculation of benefit-cost ratios (BCR). The data was statistically analysed using ANOVA and means were separated using LSD at p <0.05. Results showed significantly high BCR under conservation agriculture (p <0.0001) in all seasons with sole CA having the highest BCR of 9.9 in LR 2014. The BCRs were lower in the first season due to high initial production costs, but this increased steadily in the succeeding seasons. The study concludes that conservation agriculture both with trees and as the sole is beneficial to the farmer, with higher net benefits compared to conventional tillage