Cover crops reduce nitrogen leaching in a warmer climate
Climate change is expected to lead to increased nitrogen leaching in the Nordic countries. In his thesis, David Nimblad Svensson shows that growing cover crops is an important measure, that will become even more important in a future climate to reduce nitrogen leaching and preserve soil fertility.
Higher temperatures lead to more nitrogen being released into the soil. At the same time, more precipitation during the winter contributes to more nitrogen being leached from the soil. Therefore, the need to reduce nitrogen leaching from agricultural land will increase in the future. One effective method is to cultivate so-called cover crops. Cover crops take up nitrogen after the main crop has been harvested, which reduces the risk of nitrogen ending up in lakes and seas and contributing to eutrophication.
Long-term field experiment and modelling
In his thesis, David Nimblad Svensson at the Department of Soil and Environment has compared the effects of climate on cropping systems with and without annual sowing of perennial ryegrass as a cover crop. Among other things, he investigated how nitrogen dynamics, nitrogen leaching and harvests were affected.
– I used statistical analyses of an ongoing long-term field trial in Mellby in south-western Sweden to conduct historical studies of the years 1989–2023. I then used a soil-vegetation model and climate scenarios to simulate the coming decades up to the year 2100, says David Nimblad Svensson.
Cover crops effective in a warmer climate
His results show that the cover crop reduced nitrogen leaching both during the historical period and in the long-term simulations. The biomass and nitrogen uptake of the cover crop also increased significantly in the future scenarios as the growing season became longer. At the same time, the yield of the main crop decreased as a result of earlier sowing and the main crop maturing too quickly.
– The results of the simulations underscore the importance of optimising the choice of crops and varieties to take advantage of longer and warmer growing seasons. Future research needs to investigate both the choice of slower-maturing main crops and how other types of cover crops perform in a changing climate, says David Nimblad Svensson.
Dissertation
Link to the dissertation: Cover crop impacts on N cycling in a changing climate : long-term modelling of spring cereal systems with and without cover crops in south-west Sweden
David Nimblad Svensson defends his dissertation on the 20th of March 2026 at 9.00 in Lennart Kennes Sal, Biocentrum, Campus Ultuna, Uppsala.
Contact
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PersonDavid Nimblad SvenssonSoil and Environmental Physics