Alfalfa improves soil for future crops

Left in the field for two or three years, alfalfa helps the next crop by controlling weeds, improving soil structure, and adding nitrogen, especially when the plant is returned to the soil. This makes it a valuable component in organic farming systems.

Alfalfa fixes nitrogen more effectively

Forage legumes like alfalfa and clover are particularly good at fixing nitrogen from the air into the soil, better than grain legumes. This nitrogen helps enrich the soil for future crops, reducing the need for fertilizers.

Optimal nitrogen return from alfalfa

Julien Halska, a specialist advisor in organic arable crops, explains that the amount of nitrogen returned to the soil depends largely on the biomass left after the last autumn cut. Earlier cuts are mostly used by the alfalfa itself, not the soil.

Choosing the right crop after alfalfa

Up to 60 units of nitrogen can be saved for the next cereal or rape crop. However, wheat may not be the best choice immediately after alfalfa, as it starts absorbing nitrogen only in March. This delay can lead to nitrogen loss through leaching.

Alternative crops after alfalfa

Halska suggests growing a spring crop, where alfalfa is destroyed after winter, or destroying it earlier and planting rape, which uses nitrogen in autumn. These options can help retain more nitrogen in the soil.

Alfalfa as a temporary meadow vs. seed crop

Alfalfa grown as a temporary meadow is denser and provides more nitrogen and better weed control compared to when it is grown as a seed crop. The latter produces less nitrogen and is less effective against weeds.

Alfalfa return boosts wheat yield

An experiment in Nièvre showed that returning all alfalfa biomass to the soil after the last cut increased wheat yield by 8 q/ha compared to exporting all alfalfa, as is done in dehydrated alfalfa production. Leaving only the last cut in the field also boosted yields by 7.5 q/ha.

Economic benefits of returning alfalfa

The cost of not harvesting the last alfalfa cut is offset by the increased wheat yield, making this approach economically beneficial. This method is considered the most cost-effective by agricultural experts.