Climate and Soil Benefits of Cover Crops: Carbon Sequestration, Nitrogen Management, and Weed Control
Cover crops play a vital role in carbon sequestration by utilising the period between main crops. They contribute to stable carbon storage, particularly through roots, which have a higher sequestration potential than aboveground biomass. Grass species generally have a greater root proportion compared to brassicas, and soil properties influence sequestration efficiency. Microorganisms stabilise carbon after decomposition, and farming techniques as well as climate change can affect both sequestration and decomposition rates.
Cover crops reduce nitrogen leaching, especially in light soils, and can lower leaching by up to 43%. For optimal efficiency, nitrogen must be released at the right time for the subsequent crop. Grasses can deplete soil nitrogen in spring, whereas legumes can contribute nitrogen. A mixture of grasses and clover balances nitrogen uptake and residual effects. The timing of incorporation affects both nitrogen availability and leaching risks, particularly in sandy soils.
The impact on nitrous oxide emissions varies depending on management and crop selection. The decomposition of cover crops in wet soils can lead to high emissions, especially from brassicas such as radish and mustard.
Removing biomass in autumn for biogas production or fodder can reduce emissions. Overwintering cover crops can also lower nitrous oxide emissions by retaining nitrogen.
Cover crops also compete with weeds and can reduce weed occurrence by up to 90%. Plants such as oil radish and phacelia are particularly effective. Combining cover crops with mechanical tillage can help manage perennial weeds, and strategies such as inter-row hoeing between cover crops can control weeds without increasing nitrogen leaching.
Additional information
Much information is available for cover crops, but a more comprehensive knowledge base on variety selection and mixtures suitable for different crop rotations needs to be compiled. There is a lot of scattered knowledge among farmers that needs to be collected. Experience of which varieties work best is often very local and can differ from where you grow in Sweden.
Climate Farm Demo
Ongoing | 2022-2029
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- Horizon Europe (EU Research and Innovation Programme)
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