Grain Sorghum Response to Tillage Method Used during Fallow and to Limited Irrigation1

Abstract

AbstractIn the Southern High Plains, grain sorghum [Sorghum bicolor(L.) Moench] is grown under various irrigation regimes from full irrigation to dryland. Continued water depletion from the Ogallala Aquifer and increasing expense of pumping water have resulted in a need for developing more water‐efficient irrigated crop production systems for this area. An experiment was conducted to determine the response of grain sorghum to limited irrigation and fallow management. Winter wheat (Triticum aestivumL.) residue was managed during fallow by either no‐tillage or disk‐tillage practices. The sorghum was grown dryland or received one well‐timed growing‐season irrigation. Precipitation stored as soil water during an 11‐month fallow period was significantly higher with no‐tillage than with disk‐tillage where 1.1 kg residue m‐2 was present, but not where only 0.2 kg m‐2 was present. Dryland no‐tillage yields were greater than disk‐tillage due to greater stored water at planting. A significant irrigation × tillage interaction was found for grain yield and water use efficiency only when water stress was severe at the time of irrigation. The combination of no‐tillage during fallow after wheat and a single, well‐timed irrigation for a succeeding sorghum crop was found to be a suitable transition system from an irrigation‐on‐demand to a dryland production system.