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A computer model can effectively predict leaching from catch crops

Measurements and models agree: Reduced nitrogen leaching and improved nutrient availability are among the benefits of catch crops.

[Translate to English:] Effekten af efter afgrøder som foderræddike kan forudsiges ved hjælp af modeller. Foto: Janne Hansen
[Translate to English:] Effekten af efter afgrøder som foderræddike kan forudsiges ved hjælp af modeller. Foto: Janne Hansen

Catch crops can reduce nitrogen leaching and increase the availability of nitrogen for the subsequent crop. But how well do catch crops perform? And how well can we predict their performance using computer models? Senior Researcher Iris Vogeler from the Department of Agroecology at Aarhus University will provide answers to these questions in a lecture at the annual Danish crop congress Plantekongres 2019 that will be held in Herning January 15-16, 2019. 

- As pressures to improve efficiency and reduce environmental impacts of intensive cropping systems increase, attention has been directed towards the use of catch crops during the fall-winter season to reduce nitrogen leaching. Subsequent mineralisation of the catch crop residues can result in an increased nitrogen availability for the following commercial crop, says Iris Vogeler.  

With her colleagues in the Department of Agroecology, she used a computer modelling system called Agricultural Production Systems Simulator Model (APSIM) to determine the effect of catch crops on nitrogen leaching and nitrogen supply for the subsequent crop. APSIM is a highly advanced simulator of agricultural systems and can simulate a range of plant, animal, soil, climate and management interactions. 

The researchers took into account the amount and rate of mineral nitrogen released from catch crop residues depending on their biochemical composition.   

Computer simulation and real life agree

The simulations were based on a one-year trial carried out at AU Flakkebjerg in Denmark starting in August 2015.  The soil was either left bare or sown with a fodder radish catch crop over the autumn period.  The main crop, spring barley, was sown in April and harvested in August 2016.  

The comparison between the experimental and modelled results showed good general agreement. According to the measurements, nitrogen leaching was reduced over the winter/autumn period by 80 percent (from 47 to 10kg N/ha). The computer model predicted a reduction of 70 percent. 

The grain yield of the spring barley was increased by 16 percent when no nitrogen fertiliser was applied. At higher fertilisation rates mineralisation of the catch crop residue had no effect on the grain yield. 

Read more about Plantekongres 2019 and sign up for it here. 

Most of the lectures are in Danish, but there are several talks in English, including Iris Vogeler’s. Her talk ’Predicting mineralisation and leaching from catch crops’ will be in session 54 on Wednesday, January 16, 2019. 

For more information please contact

Senior Researcher Iris Vogeler, Department of Agroecology, email: iris.vogeler@agro.au.dk, mobile: +45 2075 5932