Effects of Supplemental Irrigation on Crop Yields: Case Study Kales (Brassica Oleracea) Crop.

The aim of this study was to investigate the effects that supplemental irrigation (SI) has on the Kale (Brassica Oleracea) crop yields as compared to the wholly rain-fed crop. The experiments were conducted in Kieni, Central Kenya where the rainfall pattern was bimodal. The planting for rain-fed crops was done in three blocks, each measuring 10x1 m with a spacing of 30 cm between plants and 45 cm between the rows of plants; the procedure was repeated for the crops receiving SI. The average weekly yields were computed for both crops for each season comprised of 14 weeks. The average weekly yields were subjected to Analysis of Variance (ANOVA) to determine whether the average yields from the rain-fed and supplemental irrigated crops were statistically different. This was done with MS Excel 2016 spread sheets by setting a statistical level of significance of 5%. The F value was 17.94 higher than the critical value of 4.01 while the P-value of 9x10(-5) was lower than the 5% level of confidence meaning that there was a significant difference in the yield means of the rain-fed and SI crops. The total rain-fed crop yields for the period was 147.0 Kgs and that of the one under SI was 238 Kgs, an increase of about 62%. Therefore, supplemental irrigation can be adopted in the areas where rainfall trends are declining to increase the crop yields when all other factors remain constant for farmers - to increase resilience.