Consequences of including adapted white clover in northern European grassland: transfer and deposition of nitrogen

Summary in the original language of the document

The interspecific transfer of nitrogen (N) between white clover (Trifolium repens) and smooth meadow grass (Poa pratensis) in legume-based grasslands was assessed under North European field conditions using 15N individual plant leaf labelling. On average 50% of N in the grass was transferred from the white clover and about 6% of N in white clover was transferred from the grass. This corresponds to 2.5 and 0.3 g N m-2 being transferred over the growing season between the two species respectively and demonstrates that a significant part of the total N of the grass is coming through interspecific transfer. The majority of the 15N transferred was within a period of 20 days at relatively low soil temperatures. This implies that there is a need for a new focus on direct transfer pathways or exudation and transfer of organic N sources. Rhizodeposition in the top 10 cm of the soil was found to be 2.98 g N m-2 on average over the growing season for the grass and white clover mixture. Inclusion of adapted white clover varieties in the low-input grassland systems of northern Europe will lead to a substantial contribution of N.