Accurately forecast final irrigation.
Agronomy Bulletin 77 ─ Corn Irrigation
The final application of irrigation water can help corn reach peak yield potential. Manage your crops with effective and responsible use of water resources.
Factors to Consider
- Physiological maturity
- Water use to maturity
- Crop stage
- Soil holding capacity
- Soil type
- Available moisture
- Irrigate to maturity. Supply enough moisture for corn to reach physiological maturity without causing crop stress and yield loss. At physiological maturity, kernels have finished grain fill and have reached maximum dry matter accumulation. A black layer will form at the lower tip of the kernel, occurring 20 days after the early dent stage and 60 days after silk. Kernels should contain 30 percent to 32 percent moisture at this stage.
- Determine irrigation amount needed. Overall, corn needs about 18 inches to 22 inches of soil moisture to reach yield potential. The final irrigation depends on such factors as crop stage, soil type, projected water use to maturity, available moisture in the soil profile and amount of water required to finish the crop without further precipitation. Corn uses less water as it grows toward maturity — allowing for delayed irrigation — but still needs moisture for the critical grain-filling stage. The requisite moisture can come from stored moisture in the lower soil profiles. Calculate if additional water is needed.
- Do not terminate irrigation early. This will accelerate maturity, keeping kernels from realizing their full potential size and weight — subsequently reducing yield potential by up to 15 percent to 20 percent. To determine how many days remain until maturity, use the table below.
- Avoid excess irrigation. Applying extra irrigation may waste water as well as fuel for delivery and pumping. Further, it raises risk of soil compaction during harvest and can limit capacity for offseason precipitation.
Managing your irrigation schedule throughout the year should include insight into determining the season’s final application. Your local Mycogen Seeds customer agronomist or trusted agronomic adviser can help calculate moisture levels so kernels can reach maximum weight.
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