skip to Main Content

Assessment of Atmospheric Deposition of Nutrients in Minnesota

Start Date: 2020
Principal Investigator: Paulo Pagliari
Co-Investigators: Fabian Fernandez and Dr. Daniel Kaiser
Organization: University of Minnesota
Status: Final

Background Info

The primary goal of this research to monitor atmospheric deposition of nutrients in selected sites. Over the last few years many of the studies being conducted to evaluate crop response to added N fertilizer are showing a decrease in the amount of N required to reach the economic optimum nitrogen rate, in certain parts of the state. One possible explanation is that more N is coming down with rainwater and snow during the winter and being stored in the soil. During the growing season, the plant can then utilize this N in addition to any other N that was applied in the fertilizer form. It is therefore, important to assess the distribution of N being deposited from atmospheric rain and snow fall throughout the state so that better N management practices can be developed and implemented.

We have installed rainwater/snow collection stations at five of the University of Minnesota Research and Outreach Centers in Crookston (NWROC), Cloquet forest center (CFC), Becker, Lamberton (SWROC), and Waseca (SROC). Water sampling started in the Spring between April and May and was collected continuously until the end of March 2021. Water pH, nitrate-N, ammonium-N, and nutrient concentration (including K, Ca, Mg, and Al) analysis was done in all of the samples from events which had enough water to be collected. However, events with less than 0.1” were not sampled because of the low amount of water collected in the gauge meter.

Objectives

The objective of this study is to monitor atmospheric deposition of nutrients in five of the University of Minnesota Research and Outreach Centers.

Key Findings

Crookston

Rainfall total reported at Crookston was 18” from April 2020 to March 2021. Rainfall water pH was highly variable; however, the pH was higher than what was observed at Becker. At Crookston rainwater pH was always above 6.0 (ranging between 6.0 and 8.0) in all events except one. The amount of rainfall in each event was evenly distributed throughout the year with very several events higher than 1”, 2.7” being the highest. The majority ranged between 0.1 and 1”. Nitrate-N concentration in the rainwater was very low and ranged between 0.01 ppm to 0.95 ppm. Ammonium-N had higher concentrations than nitrate-N and ranged between 0.06 and 16.6 ppm (very likely that the 16.6 ppm value is an outlier). Ammonium-N concentration tended to be higher in rainfall events that were below 1”.

Lamberton

Rainfall total reported at Lamberton was 28.6” from April 2020 to March 2021. Rainfall water pH was also highly variable. At Lamberton rainwater pH was never below 6.0 (ranging between 6.3 and 8.9) regardless of rainfall amount. The amount of rainfall in each event was evenly distributed throughout the year with very several events higher than 1”, 2.5” being the highest. Nitrate-N concentration in the rainwater was very low and ranged between 0.01 ppm to 1.1 ppm. Ammonium-N had higher concentrations than nitrate-N and ranged between 0.03 and 4.9 ppm.

Waseca

Rainfall total reported at Waseca was 31.9” from April 2020 to March 2021. Rainfall water pH was also highly variable. At Waseca rainwater pH was mostly above 6.0 (ranging between 5.9 and 8.2). The amount of rainfall in each event was evenly distributed throughout the year with several events higher than 1”, 4.4” being the highest. Nitrate-N concentration in the rainwater was very low and ranged between 0.01 ppm to 0.57 ppm. Ammonium-N had higher concentrations than nitrate-N and ranged between 0.05 and 2.27 ppm. Ammonium-N concentration tended to be higher in the summer and during rainfall events that were below 1.0”.

Becker

Rainfall total reported at Becker was 17” from April 2020 to March 2021. Rainfall water pH has been found to be highly variable and on rainfall below 0.5”, the pH fluctuated between 5.2 and 7.7. Whereas in events with more than 0.5” of rainfall the pH tends to be below 6.0, or more alkaline. The amount of rainfall in each event was evenly distributed throughout the year with very few events greater than 1”. Nitrate-N concentration in the rainwater was very low and ranged between 0.01 ppm to 0.51 ppm. Ammonium-N was more concentrated and ranged between 0.02 to 11.5 ppm. There was no relationship between N concentration in the water and amount of precipitation.

CFC

Total rainfall total reported at the CFC was 21.9” from April 2020 to March 2021. Rainfall water pH was as similar to the other locations and ranged between 5.0 and 8.5. The amount of rainfall in each event was evenly distributed throughout the year with several events higher than 1”, 1.94” being the highest. Nitrate-N concentration in the rainwater was very low and ranged between 0.01 ppm to 1.43 ppm. Ammonium-N had higher concentrations than nitrate-N and ranged between 0.05 and 2.75 ppm.

Back To Top