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Saving money and protecting the environment

There are benefits for both the aquatic environment and farmer revenues by improving the basis for calculating nutrient surpluses.

[Translate to English:] Kendskab til jordens kvælstofstatus kan bidrage til at optimere tilførslen af næringsstoffer. Foto: Colourbox

Researchers from Aarhus University and University of Copenhagen are collaborating with Seges in a new project that is expected to give annual reductions of agricultural nitrate leaching corresponding to 1,000 tons nitrogen and to save farmers 18 million DKK. 

The project StyrN will create a basis for field-scale nutrient accounting that the individual farmer can use to reduce nutrient surplus and increase nutrient uptake efficiency. The goal is to prepare accounts for approximately 85 percent of Danish agricultural land, which is already registered in the Danish decision support system Mark Online. 

Nutrient loss must be limited

Some of nutrients (nitrogen and phosphorus) applied in the field through fertilisers, manure and biological nitrogen fixation are lost. These losses impact the environment and are constitute a cost for the farmer. Losses can be reduced by making more precise calculations of each field’s nitrogen requirements and by adjusting crop choices. With more precise information the farmer can more readily match his crop choices with the soil’s current nitrogen status. Crop rotation can thus be optimised to use the soil’s nutrients as well as possible.   

The project partners will develop nutrient accounts on the basis of data that farmers already now report to Mark Online and that are stored in the national Dansk Markdatabase. This means there will be no need for extra entries to be made in order to calculate nutrient surplus, nitrogen loss, changes in soil nitrogen content and the most optimal crop rotation. 

Calculations take ”everything” into account

The project will improve the basis for accurate calculations of the field nutrient balances. The researchers will describe how to calculate projected yield and protein content dependent on the crop nitrogen supply. They will also describe how to calculate biological nitrogen fixation and mineralisation at field level. 

Soil nitrogen content is distributed in various pools with different turnover rates and chemical properties. Changes in the soil’s total nitrogen pool are a result of cultivation history, crop choice, straw mulching, cultivation of catch crops, and use of organic fertiliser. Soil conditions, soil tillage, and climate also affect changes in the nitrogen pool. The researchers will describe how to calculate all these conditions. 

In addition, the researchers will describe how to estimate nitrate leaching. Knowledge of the magnitude of nitrate leaching can increase the farmer’s awareness of where interventions in the crop rotation can limit nitrogen losses.   

The numerous figures, calculations and formulas as well as their interrelationships will result in a tool that will be included in Mark Online and thus automatically be offered to all farmers that use this decision support system – corresponding to approximately 85 percent of the cultivated land in Denmark. Prior to that, the tool will be tested and demonstrated on selected farms with different nutrient surpluses, soil pool changes and nitrate leaching.  

Facts about the project

Name: StyrN

Funding: Granted 4.9 million kroner from the Ministry of Environment and Food of Denmark’s Green Development and Demonstration Programme (GUDP)

Partners: Seges (project leader), Aarhus University and University of Copenhagen

Duration: 1 January 2018 to 31 December 2020

For more information please contact: Section manager, Professor Jørgen E. Olesen, Department of Agroecology, email: jeo@agro.au.dk, telephone: +45 8715 7778, mobile: +45 4082 1659

Sustainable Nutrient Management is one of the research areas in which the Department of Agroecology is particularly strong and from which results are delivered in line with national and global societal challenges and goals.