Effect of Irrigation with Waste Water on Soil Characteristics and Bean Yield: A Case Study of University of Eldoret Farm

Abstract

Experimental field treatments were set up at the University of Eldoret farm that is next to the wastewater treatment plant. The farm is located in Uasin Gishu County, Kenyan North Rift part. The field experiments were carried out between June and October 2018. The irrigation was supplemental to the reducing rainfall amounts. The key objective of the study was to evaluate the effect of wastewater irrigation on soil physical and chemical characteristics, and bean crop yield. The approach took a randomised complete block design (RCBD) where the treatments were replicated twice. For the treatments, wastewater with four levels of NPK% (0%, 25%, 50%, and 75%) and freshwater with five levels of NPK % (0%, 25%, 50%, 75%, and 100%) were applied to the plots. The freshwater at 100% NPK was considered as the control experiment. For all the plots, supplemental irrigation was carried out where equal amounts of water were applied based on crop water requirement and growth stages for the crop. CROPWAT and CLIMWAT were used as the models to simulate the correct crop water requirement and develop an irrigation schedule. Wastewater samples were collected from the tertiary pond and tested in the chemistry laboratory. Also, soil samples were collected before and after the planting period and tested in the soil science laboratory. Results showed that plots under 25% NPK and 50% NPK WW yielded more beans compared to fresh water. The soil physical structure improved while components like Nitrogen, Potassium, and Phosphorous increased with significant amounts. The use of wastewater for irrigation around the Eldoret area calls for these optimum conditions to guarantee the food sufficiency in the region and Kenya at large. The irrigation schedule can be used as a decision-making tool for the local farmers to achieve an optimum irrigation efficiency. More research and awareness is required for the cultural aspect that surrounds use of waste water irrigation in the local communities.