When it comes to classification of cover crops, you can divide the crops in 3 categories: the grassy crops, the leafy crops and the leguminous crops. They all have their qualities!
By making an informed choice this cover crop can help in
pest control
increase of soil organic matter
enhance soil quality
reduced erosion
increased water quality
This websites can help you with the choice of the cover crop:
levendebodem.eu (Dutch)
Brochure 'Functional guideline cover crops with maize' (Dutch)
Protect'eau (French)
Multifunctionality of intercrop crops (French)
Arvalis Choice of species (French)
A more complex choice of species (French)
Leafy species can quickly take up big amounts of nitrogen. Because of their deep roots, this can be done from deeper soil layers compared to the grassy species. Nitrogen release occurs fast after incorporation. The amount of biomass generated, and therefore the amount of soil carbon sequestration, is lower than with grassy species.