Measurement of Crop Water Requirement and Developing Crop Coefficient (Kc) for Irrigation Scheduling of Wheat Crop Using Lysimeter at Bishofitu

Abstract

With Rapid Population Growth, Pressure On Natural Resources Such As Water Is Aggravating. Consequently, Shortage Of Water Also Competition For The Available Water Is Increasing In Many Regions. Scarcity Of Fresh Water For Agricultural Use Is Forcing The Society To Look For Different Planning And Management Options. This Requires Knowledge Of Crop Specific Parameters That Are Needed For Irrigation Development And Management. The Objectives Of This Research Were To Determine The Crop Evapotranspiration, Develop Crop Coefficient And Irrigation Scheduling For Wheat Crop. The Study Was Conducted In Bishoftu, At Debre Zeit Agricultural Research Center (DZARC).The Experiment Was Conducted During The Dry Season (Bega) Of 2021/22 With Sample Crop Of Utuba Variety Durum Wheat. For This Purpose, Two Non-Weighing Lysimeter Units Were Used For Measuring Water Balance Components On Daily Basis From Which Crop Evapotranspiration Was Calculated And Then Crop Coefficient. The Total Crop Growing Length Was 115 Day Starting From Day After Sowing Which Was Assigned 20, 30, 42, And 23 Days For Initial, Development, Mid, And Late Stage Respectively. The Reference Evapotranspiration Was Estimated With Cropwat8.0 Model And Microsoft Excel Was Used For The Data Analysis. The Soil Moisture Content Was Monitored With Gravimetrical Method And Monitoring Was Carried Out Before And After Every Irrigation Applications With Different Depth Interval. The Results Indicated That The Crop Evapotranspiration Of 40.35 Mm, 82.44 Mm, 238.66 Mm, And 31.3 Mm Was Recorded For Initial, Development, Mid, And Late Growing Stage Respectively With Total Seasonal Water Requirement Of 392.75 Mm. The Crop Coefficient Was Estimated To Be 0.51, 0.83, 1.29, And 0.52for Initial, Development, Mid, And Late Stage Of Wheat Growth Respectively And Fourth Degree Polynomial Equation Was Developed For The Relationship Between DGS And Kc Also Sixth Degree With DAS. As The Findings Indicated, There Is Variation On Kc Result From FAO Recommended values Ranging Between -30 % To +63.5 %. The Irrigation Scheduling Was Developed Based On Peak Daily Crop Evapotranspiration And The Result Indicated 10, 12, 27, And 9 Days Interval Is Required For Initial, Development, Mid, And Late Season Of The Crop Growing Stages Respectively. As Of The Result Of This Study, Parameters To Be Calibrated And Validated With Respect To Desired Location If It Is Different From The Conditions Under Which They Are Developed For. Therefore, Crop Water Requirement, Crop Coefficient And Irrigation Scheduling Are Essential Parameters For Efficient Irrigation Water Management, Planning And Precise Water Application