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HARTINGTON —With harvest in full swing and preparation for next year’s crop underway, the Lewis and Clark Natural Resources District (LCNRD) reminds landowners and crop producers that commercial fertilizer applications are not recommended in the fall. If you apply commercial fertilizer, it is recommended that applications not take place between September 30th and March 1st each year.
LCNRD recommends water quality testing for irrigation wells and deep soil sampling for cropped acres. Knowing how much nitrogen is available to the crop from irrigation water and the soil is essential to determining how much N is needed to achieve realistic yield goals while protecting groundwater from potential leaching of excess nitrogen. Knowledge of what is available to the crop through irrigation water and soil nitrogen sources improves estimates for N application rates when based on total N requirements for the crop to be grown. When excess N is applied, it is typically flushed past the root zone by precipitation or irrigation, eventually contaminating groundwater and causing additional expense for producers.
Proper timing of N fertilizer application is critical for water quality. Applying nitrogen to these soils before the crop’s growth stage can lead to nitrogen leaching into the groundwater below. It is recommended that nitrogen be “spoon-fed” to the crop to avoid over-application. Some methods to improve nitrogen fertilizer efficiency and minimize over-application and leaching include fertigation, side dressing, nitrification and urease inhibitors, slow-release formulation, irrigation management, and setting realistic yield goals (Ferguson, UNL, 2011). These methods are effective for managing nitrogen availability throughout the growing season while minimizing leaching potential. With the dry conditions this year, nitrate levels in the soil profile could be high in some areas, and soil testing is necessary to determine appropriate N rates for next year’s crops. If you have any questions about fall fertilizer application or water quality sampling, contact the LCNRD at 402-254-6758 or your local UNL Extension Coordinator.
