Nitrogen Management in Drained Soils
There continues to be growing concern about the impact of nitrogen fertilization on water quality. But the problem isn’t as simple as reducing nitrogen fertilizer rates – growers also need to consider the prevalence of nitrogen in the environment. University of Minnesota Extension Educator Brad Carlson shares how proper nitrogen management can have a positive impact on water quality in drained soils with research from Waseca, Minnesota.
In summary, there are three main ways nitrates move to surface water: overland runoff, shallow groundwater flow, and artificial drainage. Studies have shown that very little nitrate moves via runoff. Groundwater and drainage show similar results, but water tends to move much faster through a drainage system. With this in mind, Carlson discusses how drainage plots developed near Waseca and Lamberton, Minnesota, have been used to craft the university’s nutrient management best management practices (BMPs) in regard to water quality. Research compared spring and fall nitrogen application timing, application rates, and crop rotation.
Some nitrate-nitrogen may be lost from the soil even in the absence of fertilizer nitrogen because of natural mineralization of soil organic nitrogen. BMPs can help reduce loss of fertilizer nitrogen. Some BMPs noted that can reduce nitrate leaching losses include applying nitrogen in spring instead of fall, growing cover crops during the time between harvest and the next planting, and avoiding nitrogen in excess of crop economic-optimum rates.
Watch the video or visit the University of Minnesota Extension website for more information.