Short-term effects of a dung pat on N2 fixation and total N uptake in a perennial ryegrass/white clover mixture

摘要: The short-term effects of a simulated cattle dung pat on N2 fixation and total uptake N in perennial ryegrass/white clover mixture was studied container experiment using sheep faeces mixed with water to DM content 13%. We used new 15N cross-labelling technique determine the influence dung-pat grass/clover grass clover. proportion derived from (%Ndfa) varied between 88–99% during 16 weeks following application dung. There no effect %Ndfa grown mixture, whereas pure stand decreased (nominal 2–3%) after application. Dung did not amount fixed, proceeded at an almost constant rate. After weeks, 10% applied taken up by clover, 57% had been incorporated soil faunal activity 27% remained residual surface. unaccounted for (7%) probably lost ammonia volatilisation denitrification. mixtures field similarly followed 15N-labelled pats. dry matter production yields increased 0–30 cm distance edge patch, but decreased. Thirteen months 4% recovered harvested herbage, 78% dung, 18% accounted for. It is concluded that patch border area influenced directly release pats short term. However fixed may be reduced, if growth reduced area.