Strategies for Irrigating Winter Wheat

Phillip Sylvester, Extension Agriculture Agent, Kent County; phillip@udel.edu; Cory Whaley, Extension Agriculture Agent, Sussex County; whaley@udel.edu; James Adkins, Associate Scientist-Irrigation Engineering; adkins@udel.edu

Winter wheat has begun the rapid growth phase, and it will soon reach head emergence. Warm temperatures and lack of recent rainfall have depleted soil moisture levels. Growers with the ability to irrigate should consider doing so, with the goal of keeping available water content >50%. We conducted research sponsored by the Delaware Crop Improvement Association from 2013 to 2016 to evaluate the impact of various irrigation strategies on yield and to determine the optimal strategy to maximize yield. We’ll skip right to the results – irrigation resulted in significantly higher yields in three of four years compared to a non-irrigated check. On average, yields were 7-14% higher compared to the non-irrigated check. There were only slight differences between the various irrigation strategies. However, we discovered a significant trend; adequate soil moisture levels must be maintained before flower and at levels high enough to support the crop through flowering and early grain fill. Our take home message is to consider irrigating during periods of dry, warm weather a couple of weeks before and after flowering. Growers should adopt an irrigation strategy that monitors soil moisture levels early on and that provides enough water to carry the plant through flowering and early grain fill. Given the extended period of dry weather and variable soils throughout the state, plan to check your own fields now. Use a soil probe to determine your soil moisture level within the depth of the root zone. Continue to monitor your soil moisture level after each irrigation to ensure adequate water is available within the root zone. It may take multiple passes with the irrigation to fully recharge the soil profile.

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