Lepa and Spray Irrigation of Cornsouthern High Plains

Two LEPA and two spray sprinkler methods were evaluated with five irrigation amounts ranging from 0 to100% of soil water replenishment in 25% increments. The LEPA methods were bubblers at the 0.3-m height and doubleendedsocks pulled through the furrows, and the spray methods were in-canopy spray at the 0.3-m height and overheadspray about 0.3 m above the mature crop canopy. The 100% irrigation treatment received 25-mm irrigations to maintainsoil water at a non-yield-limiting level based on earlier research. Neutron soil water measurements verified the adequacyof the irrigation applications. Deficit irrigation treatments received 0, 25, 50, and 75% of the 25-mm irrigations on thesame date. The field study was conducted on Pullman clay loam soil at Bushland, Texas, during the 1994 and 1995 cropyears. Tillage, fertility, and weed and insect control were typical of those used for high-yield, on-farm corn production inthe Southern High Plains. The corn was planted on 0.76-m spaced beds, all furrows were diked, and sprinkler deviceswere spaced 1.52 m apart over alternate furrows. Grain yields and seasonal water use efficiency (WUE) both increasedsignificantly with irrigation amount. For 100% irrigation across the four sprinkler methods, grain yields and WUEaveraged 13.5 Mg/ha and 1.68 kg/m3, respectively. Significant differences in grain yields and WUE occurred among thesprinkler methods in 1994, but the yields and WUE were not consistently larger for either the LEPA or spray sprinklermethod. In conclusion, both LEPA and spray are efficient sprinkler methods for irrigating corn for high grain yields in theSouthern High Plains.