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Nitrate in Tile-Drain Relative to Time and Source of Nitrogen Application

Start Date: 2014
Principal Investigator: Fabian Fernandez
Organization: University of Minnesota, Department of Soil, Water, and Climate
Status: Ongoing

Background Info

Sound nitrogen management is a key component to minimizing environmental degradation and improving farmer’s profitability. Nitrogen fertilization in agricultural lands in much of the Midwest has been linked to water quality issues in the Gulf of Mexico. Currently, Minnesota and other Midwestern states have or are developing Nutrient Reduction Strategies to reduce nitrate loads. while we have learned much about some of the practices that can help us achieve reductions in nitrate loads to the Mississippi River, still there are many uncertainties on how well some N management practices work.

Objectives

Quantify the effect of timing on N application and N sources on nitrate concentration and load in tile-drain water

Quantify nitrogen use efficiency in terms of corn N uptake and yield based on fertilization management

Key Findings

Finally, this year as part of a large Midwest regional study we included nitrous oxide measurements in this study. The results were similar to what we observed with nitrate leaching in that ESN pre-plant had the lowest cumulative flux compared to the other three treatments (Fig. 5). These data clearly show an advantage to using ESN during wet years. It was clear that pre-plant urea suffer substantial N loss as nitrous oxide soon after the application while pre-plant ESN and the split applications were very low. Unfortunately, soon after the split applications were done, we received substantial precipitation and both split application treatments loss substantial amounts of N (similar to the pre-plant urea treatment during early July). These data along with the nitrate leaching data and the fact that ESN pre-plant had the highest yield highlight that this N source may be a beneficial source during wet springs. Nitrous oxide emissions in conjunction with the measurements we were already collecting make this a unique and valuable study as scant data are available where both measurements are done at the same time.

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