Multi-Faceted Approach to Nitrogen Management

aerial map of field spreading in agriculture
Photo: Rich Meinert

We have a multi-faceted approach to nitrogen management in Connecticut that addresses land use issues, agricultural production, and water quality. 

Extension faculty from the Center for Land Use Education and Research (CLEAR) are working on several applied research projects in support of better nitrogen (N) management. They are collaborating with the University of Rhode Island and EPA to create an online tool, “N-Sink,” to track the movement of N in coastal watersheds (Highlights, 2020). In a project funded by the Long Island Sound Study (LISS), they are using cutting-edge high resolution land cover data to explore the relationship of land use to N export for the over 4,300 small watershed basins in Connecticut. Finally, the CLEAR geospatial team is part of another LISS study, led by Dr. Ashley Helton of the 

Department of Natural Resources and the Environment, that is looking at “legacy” N loadings that are derived from past land uses that are no longer apparent but that continue to export N to our waters. 

Rich Meinert is working with three farms on developing accurate as applied maps for farm applications. Current as applied maps provided by GPS systems are inaccurate on smaller New England farms. Our small irregularly shaped fields require spreaders to negotiate tight turns. Current generation software does not calculate the differences in as applied rates between the inside and the outside of a turn. Preliminary measurements using equipment on one of the farms has resulted in a 30% decrease in application rate on the outside of a turn versus the inside of the turn. 

Another challenge in our smaller fields is overlap. Current spreaders have a fixed operating width. They throw lime, fertilizer, or manure with a set amount of force, across a fixed width, or they spray manure, or pesticides from a single point or a set of nozzles with a certain pressure and spray pattern, like a paint sprayer. Having a fixed application width and a varying field shape inevitably results in overlap. Certain sprayers can shut off nozzles to prevent overlap, but fertilizer and manure spreaders cannot vary their discharge. This research is currently collecting data to develop a computer algorithm to show where the nutrients are actually going so that future nutrient applications can target areas of fields that need it, and avoid areas that have had excess nutrients applied previously.

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Article by Chet Arnold and Rich Meinert

New option for taking nitrogen samples

Posted on January 24, 2020 by Amanda Ryan

There wasn’t a cheap and simple way to take field measurements of Total Nitrogen (TN).  Samples had to be sent to a lab – until now!

To help reduce water quality testing costs, CT DEEP agreed to allow MS4 communities to use less expensive field tests for nitrate and ammonia to estimate Total Nitrogen.  If your TN estimate exceeds 2.5 mg/L then a sample should be brought to a lab to officially determine its Total Nitrogen value. If the results are below 2.5 mg/L, you do NOT have to conduct additional nitrogen testing.

To estimate TN for your sample, plug in your values for nitrate (mg/L) and ammonia (mg/L) into this formula:  TN=1.94 x [(nitrate + ammonia) ^ 0.639]

 When do I have to sample for Total Nitrogen again?

There are a few situations where the MS4 permit requires towns and institutions to sample for Total Nitrogen (TN):

Dry weather baseline screening:

If you see flow during dry weather baseline screening at an outfall that discharges directly to a waterbody impaired by Nitrogen (or ‘Nitrogen and Phosphorus’).

Catchment investigation procedure:

Wet weather sampling of outfalls during the catchment investigation procedure when the receiving waterbody is impaired by Nitrogen (or ‘Nitrogen and Phosphorus’).

Impaired waters monitoring:

If there is a waterbody impaired by Nitrogen (or ‘Nitrogen and Phosphorus’), you need to sample the wet weather discharge from any MS4 outfall that empties directly into that waterbody.

An easy way to see if there is a Nitrogen (or ‘Nitrogen and Phosphorus’) impaired waterbody in your town, go to the MS4 Map Viewer and click on any purple or red waterbody to see what’s listed as its Stormwater Pollutant of Concern in the pop-up window

Nitrogen – The Fix

Chlorotic corn. Image provided by T. Morris, 2018

Nitrogen is an essential nutrient required for the production and growth of all plants, vegetation, and living organisms. It makes up 78% of our atmosphere; however, that only accounts for 2% of the Nitrogen on our planet. The remaining 98% can be found within the Earth’s lithosphere; the crust and outer mantel. The Nitrogen found within the nonliving and living fractions of soil represents an unimaginably low fraction of a percentage of all the Nitrogen on our planet. That tiny percent of all total Nitrogen found in our soils is what we can interact with to help or hinder plant production.

To be considered an essential nutrient, an element must satisfy certain criteria:

  • Plants cannot complete their life cycles without it.
  • Its role must be specific and defined, with no other element being able to completely substitute for it.
  • It must be directly involved in the nutrition of the plant, meaning that it is a constituent of a metabolic pathway of an essential enzyme.

In plants, Nitrogen is necessary in the formation of amino acids, nucleic acids (DNA and RNA), proteins, chlorophyll, and coenzymes. Nitrogen gives plants their lush, green color while promoting succulent growth and hastens maturity. When plants do not receive adequate Nitrogen, the leaves and tissues develop chlorosis. However, over-application of Nitrogen can cause even more problems, including delayed maturity, higher disease indigence, lower tolerance to environmental stresses, reduced carbohydrate reserves, and poor root development.

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