Legumes play a crucial role in nitrogen
supply to grass-legume mixtures for ruminant fodder.
To quantify N transfer from legumes to neighbouring
plants in multi-species grasslands we established a
grass-legume-herb mixture on a loamy-sandy site in
Denmark. White clover (Trifolium repens L.), red
clover (Trifolium pratense L.) and lucerne (Medicago
sativa L.) were leaf-labelled with 15N enriched urea
during one growing season. N transfer to grasses
(Lolium perenne L. and xfestulolium), white clover,
red clover, lucerne, birdsfoot trefoil (Lotus corniculatus
L.), chicory (Cichorium intybus L.), plantain (Plantago
lanceolata L.), salad burnet (Sanguisorba minor L.)
and caraway (Carum carvi L.) was assessed. Neighbouring
plants contained greater amounts of N derived
from white clover (4.8 gm-2) compared with red clover
(2.2 gm-2) and lucerne (1.1 gm-2). Grasses having
fibrous roots received greater amounts of N from
legumes than dicotyledonous plants which generally
have taproots. Slurry application mainly increased N
transfer from legumes to grasses. During the growing
season the three legumes transferred approximately
40 kg N ha-1 to neighbouring plants. Below-ground N
transfer from legumes to neighbouring plants differed
among nitrogen donors and nitrogen receivers and may
depend on root characteristics and regrowth strategies
of plant species in the multi-species grassland.