Abstract

A grassland field experiment with experimentally controlled plant species richness (1, 2, 4, 8 and 12 species) was conducted during 1996-2002. Nitrate in soil water was sampled during 1998 to 2001 and aboveground plant N content was determined for each species during 1998, 2000, 2001 and 2002. In the year 2000, ice covered ground during winter combined with severe spring frost, caused most of the clovers in the experimental plots to die. High nitrate concentrations were found in the soil water in pure legume plots after the disturbance (up to 37 mg NO3-N per litre soil water). Pure legume communities had a calculated nitrate loss of 20-23 kg N per hectare during May to October. The nitrate losses in red clover/timothy plots were less than 1 kg N per hectare during the same period. In grass monocultures, leaching losses were negligible. In 2000 and 2001 log nitrate leaching was positively correlated to legume percentage in aboveground biomass the previous year. Nitrogen yield in non-legumes grown in mixtures, compared to N-yield in monoculture (N-overyield), was enhanced by the presence of legumes. However, 2000, the year of the disturbance, this difference was not significant. Also plant communities without legumes had significant N-overyield

Keywords

nitrate; diversity; N-overyield; grassland; clover

Published in

Book title: Sward dynamics, N-flows and forage utilisation in legume-based systems
ISBN: 88-89402-05-9
Publisher: ERSA- Azienda regionale per lo sviluppo rurale

Conference

2nd Cost 852 workshop

Authors' information