Biological nitrogen fixation, e.g., in the root nodules of clover , is an important source of nitrogen on organic farms. Clover also has numerous other beneficial properties. At the same time, we have observed that the clover percentage in organic grassland is often low. We will therefore determine the clover percentage in grassland on 20 organic farms. Where there is little clover, we will suggest causes.

The project is carried out as a cooperation between NORSØK and three regional offices of the Norwegian Agricultural Advisory Service (NLR). The advisory service will select farms that are typical for the organic farms in their respective regions. Of these, 10 farms are in south-eastern Norway, six are in Trøndelag and four in Møre og Romsdal. Plant species composition will be determined during regrowth after the first cut. The advisory service will select three fields per farm on which clover percentage will be assessed. We will also examine the roots to see if they have active nodules for nitrogen fixation. Finally, we will take soil samples to determine pH and to test for clover nematodes in cases with poor clover growth.