The effects of plant diversity on productivity, nitrogen dynamics and soil microbial diversity in grassland systems - verkefnislok
Fréttatilkynning verkefnisstjórans
Analyses of yield data over a period of five harvest years has confirmed significant positive diversity effects in all individual years and averaged across the five years.
Grassland-based livestock systems play an important role as
a provider of food in the more marginal areas in Nordic regions. Such
production systems are commonly dominated by grass monocultures receiving
relatively high levels of fertilizer. The objective of the current project was
to analyse whether grass-clover mixtures affect the productivity, stability, N
fluxes and soil microbiota when grown under sub-arctic conditions and how these
effects are influenced by N fertilisation.
Heiti verkefnis: The effects of plant diversity on
productivity, nitrogen dynamics and soil microbial diversity in grassland
systems
Verkefnisstjóri: Áslaug Helgadóttir, Landbúnaðarháskóla Íslands
Tegund styrks: Verkefnisstyrkur
Styrkár: 2013-2015
Fjárhæð styrks: 16,15 millj. kr.
Tilvísunarnúmer Rannís: 130383-051
Analyses of yield data over a period of five harvest years has confirmed significant positive diversity effects in all individual years and averaged across the five years. Across years, the four-species equi-proportional mixture was 71% (N20) and 51% (N70) more productive than the average of monocultures and the highest yielding mixture was 36% (N20) and 39% (N70) more productive than the highest yielding monoculture.
Importantly, diversity effects were evident also at low relative abundances of either species group, grasses or legumes, in the mixture, indicating additional nitrogen input into the system through the access of the legume component to atmospheric N2. This implies that the application of synthetic nitrogen fertiliser could be substantially reduced. Our results demonstrate that northern grassland production can benefit from grass-legume systems, that these benefits can be sustained over five harvest years and that they were robust over years, N fertilizer treatments and a wide range of relative proportions of legumes in the mixture. Analyses of data relating to N fluxes and soil microbiota still need to be completed and prepared for publication.
Results obtained so far have been presented and published at the European Grassland Federation (EGF) conferences and one paper awaits publication in an international peer-reviewed journal.
