Nimblad Svensson, David
- Department of Soil and Environment, Swedish University of Agricultural Sciences
Abstract
Climate change is expected to increase nitrate leaching from arable land in the Nordic countries due to increases in temperature and winter precipitation. Growing cover crops (CCs) is the most important mitigation strategy in spring cereal dominated systems. In this thesis, data from a long-term field experiment in southwest Sweden was used to study the effects of growing under-sown perennial ryegrass (Lolium perenne L.) as a cover crop on N leaching, soil organic nitrogen (SON), N mineralisation and yield under present and future climate. The methodology involved statistical analysis of 34 years of field measurements combined with simulation modelling. The model was calibrated against field data from treatments with (CC_90N) and without (90N) cover crops. It was also used to make projections for future climate (2020–2100) with input from five coupled global and regional climate models for three representative concentration pathways (RCP 2.6, 4.5 and 8.5). The CC effectively reduced N leaching with no decline in efficiency over 34 years. Total N leaching in 90N was positively correlated with temperature and the North Atlantic Oscillation index (NAOi), whereas in CC_90N, only N uptake by the CC was positively correlated with NAOi. Model simulations showed that annual N mineralisation in CC_90N increased over time due to higher temperatures and the repeated incorporation of CC biomass into the soil. Nevertheless, simulated N leaching increased more in 90N than in CC_90N. N uptake by the CC increased substantially in a future climate, partly because harvest of the main crop occurred earlier in the season, especially in scenarios with RCP 4.5 and 8.5. The cover crop efficiency expressed as % reduction in N leaching compared to the treatment without CC, increased over time under RCP 8.5. Thus, under-sown perennial ryegrass could efficiently compensate for both earlier harvests and increases in N mineralisation in a warming climate. Yields did not differ between the two treatments in the current climate, while simulated SON increased in CC_90N, but decreased over time in 90N both in present and future climates.
Keywords
Nitrogen leaching; cover crops; climate change; agroecosystem modelling; climate scenarios
Published in
Acta Universitatis Agriculturae Sueciae
2026, number: 2026:13
Publisher: Swedish University of Agricultural Sciences
SLU Authors
UKÄ Subject classification
Agricultural Science
Soil Science
Publication identifier
- DOI: https://doi.org/10.54612/a.4qvuiq5pba
- ISBN: 978-91-8124-210-2
- eISBN: 978-91-8124-230-0
Permanent link to this page (URI)
https://res.slu.se/id/publ/145794