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Evaluation of Variable Rate Nitrogen Technologies for Corn in Minnesota

Start Date: 2013
Principal Investigator: Jeffrey Vetsch
Organization: University of Minnesota, Department of Soil, Water, and Climate
Status: Ongoing

Background Info

Improving nitrogen (N) use efficiency in crop production is important for obvious economic and environmental reasons. Nitrogen fertilization of corn usually provides the greatest return on investment of any crop input; therefore, farmers and their agricultural advisors must insure adequate N is available for the crop to maximize yields and economic returns.
Crop rotation, N source, N rate, time of N application and the use of N stabilizers are all factors considered when making N recommendations. Generally, N application timing and N rate are the most scrutinized of these management decisions. The objectives of this research project are 1) to demonstrate and evaluate soil-based (PSNT) methods for making in-season N rate adjustments (recommendations); 2) to evaluate the method’s ability to integrate climate and landscape based variability at the field scale; 3) to compare this PSNT approach for making N recommendations to a conventional preplant application by measuring grain yield, N removal, residual soil nitrate and economic return; and 4) to determine if the PSNT approach will improve N management for corn in Minnesota.

Objectives

Demonstrate and evaluate soil-based (PSNT) methods for making in-season N rate adjustments (recommendations)

Evaluate the method’s ability to integrate climate and landscape based variability at the field scale

Compare this PSNT approach for making N recommendations to a conventional pre-plant application by measuring grain yield, N removal, residual soil nitrate and economic return

Determine if the PSNT approach will improve N management for corn in Minnesota

Key Findings

The 2015 PSNT data showed rapid NO3-N concentrations were greater at the V6 stage than at V2 at NF15; whereas, NO3-N concentrations were greater at V2 than at V6 in CG15 and WA15.

These differences may have been related to the N sources used at each location, anhydrous ammonia at NF15 and urea at CG15 and WA15.

However, it is more likely that N loss was greater at CG15 and WA15 locations due to greater rainfall and a greater extent of poorly drained soils.

The changes in soil nitrate observed over time in this study have major implications for using PSNT values for determining sidedress N rates.

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