Quantifying water savings with greenhouse farming

Greenhouses can help farmers reduce spoilage and increase yields, and therefore improve their livelihoods. As compared to open air farming, greenhouse farming requires less water due to reduced evapotranspiration. Current estimates on water savings vary from 10 to 100% and fail to clearly specify relevant test parameters such as the irrigation method, size of the greenhouse, or climatic conditions at the time of the study. This article focuses on a study conducted to accurately quantify the water savings in small-scale greenhouses. The test methodology involves a simplified pan evaporation measurement used with the Penman-Monteith and Hargreaves equations. Data, including air temperature, relative humidity, wind speed, and water loss inside and outside the greenhouse, were collected from similar greenhouses in Kenya and Cameroon. Results indicate that the water savings within greenhouses are around 50-90%. This significant reduction in water consumption allows for agricultural intensification as well as horticultural production in arid and semi-arid regions that make up over 80% of the land in several African countries.