Crop Evapotranspiration, Irrigation Water Requirement and Irrigation Scheduling of Soybeans under Sprinkler Irrigation system at Nasho Sector, Rwanda

Abstract

The study aimed to estimate the Crop Water Requirement of Soybean plant under sprinkler irrigation system at Nasho Sector, Rwanda. Experimentally, the study covered the total area of 30mx60m to give 1800m². It means that each plot contained 10m width versus 60m height with one installed movable sprinkler. While for water collection from nozzles, catch cans were used to collect the discharge rate. After pumping water to sprinklers, the research should pass 15min and record the discharge rate in each experimental plot for 3 catch cans in each sub plots to make 3plots*3 catch cans* 3sub plots and give 27 water samples for whole experimental site. The Cropwat 8 computer packages was used to compute Reference evapotranspiration, Crop water Requirement and irrigation scheduling in sprinkler irrigation installed for soybeans production. The study findings showed that the mean ETo of soybean was found to be 4.79 mm/day. For crop water requirement, it was found that the total of rain fall was 785.2mm while the effective rain fall was found to be 678.8mm for the period of twelve months. For irrigation scheduling, It was found that the total Crop evapotranspiration of soybean was 678.4mm/dec while effective rainfall need per soybean production was found to be 134.9 mm/dec and the Irrigation water requirement per soybean under sprinkler irrigation system was found to be 547mm/dec. It is concluded that that the total amount of water stored in soybean root zone is less than the total needed water and soy beans can suffer from water deficit. For crop water requirement, it was also found that the total of rain fall was higher than effective rain fall stored in root zone for the period of twelve months and these implies higher Crop water need and as results Maximum potential yield for most irrigated soybeans crops in the study area has increased substantially during the irrigated area with sprinkler system. In addition, there is an economic gains in soybean productivity that are attributed to improved plant management, modern irrigation practices associated to better agronomic management practices than those used in the past. It is also recommended that different riser heights may also be studied to observe their effect on the measures of sprinkler irrigation system performance, to cater for the cultivation of other crops.