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Home (English) >> Research >> Agriculture >> Soils >> Green manures

Green manures offer innovative answer to nutrient management regulations

Green manures such as grass-clover and alfalfa make good fertilizers. They have a favourable N to P ratio and a predictable nitrogen activity, so they are easily applied. In dealing with the stricter nutrient management regulations - requiring organic farmers to exclusively use manures from organic farms - green manures provide an innovative solution.

On-farm trials

The Louis Bolk Institute is presently conducting various on-farm trials comparing applications of alfalfa with manure slurries and chicken manure. We are also comparing the effects of fresh cut alfalfa with silaged alfalfa, added either 5 weeks or 10 days before sowing a crop. The field trials are conducted in Ens, Strijen, Sevenum, Lelystad, Almere en Mill (the Netherlands). Soil nitrogen dynamics are analyzed using our NDICEA nutrient model. The results of the field trial in Ens have already been published in a report (in Dutch).

Alfalfa offers an affordable alternative

Organically produced animal manure is becoming more expensive. At the same time, organic farmers have to meet stricter organic soil fertilization requirements. Alfalfa could serve as an affordable alternative to animal manure. The nitrogen content of silaged alfalfa is 9.9 kg per tonne compared to 4.9 kg per tonne in animal manure slurry. The first analysis results are promising. We will publish the comprehensive results of all trials in September 2010.

'SKAL' organic regulations also apply to alfalfa

Alfalfa can be applied as dry granules or fresh cuts. Whether alfalfa applications should be included in the farm nutrient records depends on whether the alfalfa was produced on-farm or imported from other farms. Up-to-date information on organic soil fertilization standards and record-keeping requirements can be found on the website of SKAL.

If you are interested in this project or in one of our other soil projects, please subscribe to the e-newsletter of the Soil Academy (in Dutch).
Additional information can be obtained from Geert-Jan van der Burgt at the Louis Bolk Institute.

You may also like to read:
Soil research at the LBI
New soil fertilization methods (in Dutch, summary in English)