Effect of Deficit Irrigation on Drybean Soil Moisture Dynamics, Evapotranspiration, Yield, and Water Use Efficiency.

Wyoming agriculture is highly depended on irrigation. Quantifying the crop response to irrigation is important for establishing adequate irrigation management strategies. In this on-going study, the effect of different irrigation regimes on dry bean (Phaseolus vulgaris) grain yield, Pod-Harvest Index (PHI), evapotranspiration (ETc), and crop and irrigation water use efficiency (CWUE and IWUE), and yield response factor (Ky) were investigated in the semi-arid climate of Northwest of Wyoming. Five irrigation regimes [full irrigation treatment (FIT), 75%FIT, 50%FIT, 25%FIT and 125%FIT] were evaluated under sprinkler and surface irrigated dry beans. Drybean yield and PHI varied from 264 kg/ha and 72% for 25% FIT treatment to 3287 kg/ha and 75% for FIT treatment, respectively. Contrary to sprinkler irrigated drybeans, the maximum yield of 2469 kg/ha and PHI of 75% was observed for 50% FIT and minimum yield of 1558 kg/ha and PHI of 72% was observed for 125% FIT under surface irrigated drybeans. ETc was observed to be maximum for 125% FIT under both the irrigation systems and increased with irrigation levels. In sprinkler irrigated drybeans, the maximum CWUE and IWUE of 0.99 kg/m³ and 1.26 kg/m³ and minimum of 0.15 kg/m³ and 0.29 kg/m³ were observed for FIT and 25%FIT, respectively. In surface irrigated drybeans, the maximum CWUE and IWUE of 0.97 kg/m³ and 1.24 kg/m³ and minimum of 0.41 kg/m³ and 0.32 kg/m³ were observed for 25%FIT and 125%FIT, respectively. These results indicate that irrigation amount and mode of application can significantly impact yield and growth of drybeans. Moreover, excess irrigation does not result in higher growth and yield. This is an on-going study and result from the second year will help decide on the best irrigation management practice with more confidence.