Denitrification, leaching and immobilisation of applied 15N following legume and grass pastures in a semi-arid climate in Australia

摘要: Four consecutive 15N mass balance experiments lasting 18 months from February 1993 to August 1994 were carried out assess the fate of applied at 3 sites after 4 years lucerne or snail medic and 20 Mitchell grass/naturalised pastures respectively in Roma district Queensland, Australia. loss via denitrification was estimated difference between recovery Br(100kg Br/ha) that 15N(40kg N/ha) top 250mm end each experiment. From 1993, losses 12–38% 15N. N increased 36–51% during November responding higher rainfall this period. With even more period March 1994, be 16–23%while displacement below 250 mm 74–81%. When much less only 15–19% occurred sites. It found although dominant factor controlling 15N, soil available carbon (C) (measured as water-soluble C) quantity nitrate also important for soils already containing a considerable organic matter residues pasture legumes.