Summary 1.A coordinated continental-scale field experiment across 31 sites was used to compare the biomass yield of monocultures and four species mixtures associated with intensively managed agricultural grassland systems. To increase complementarity in resource use, each of the four species in the experimental design represented a distinct functional type derived from two levels of each of two functional traits, nitrogen acquisition (N 2 -fixing legume or nonfixing grass) crossed with temporal development (fast-establishing or temporally persistent). Relative abundances of the four functional types in mixtures were systematically varied at sowing to vary the evenness of the same four species in mixture communities at each site and sown at two levels of seed density. 2. Across multiple years, the total yield (including weed biomass) of the mixtures exceeded that of the average monoculture in >97% of comparisons. It also exceeded that of the best monoculture (transgressive overyielding) in about 60% of sites, with a mean yield ratio of mixture to best-performing monoculture of 1Á07 across all sites. Analyses based on yield of sown species only (excluding weed biomass) demonstrated considerably greater transgressive overyielding (significant at about 70% of sites, ratio of mixture to best-performing monoculture = 1Á18).3. Mixtures maintained a resistance to weed invasion over at least 3 years. In mixtures, median values indicate <4% of weed biomass in total yield, whereas the median percentage of weeds in monocultures increased from 15% in year 1 to 32% in year 3. 4. Within each year, there was a highly significant relationship (P < 0Á0001) between sward evenness and the diversity effect (excess of mixture performance over that predicted from the monoculture performances of component species). At lower evenness values, increases in community evenness resulted in an increased diversity effect, but the diversity effect was not significantly different from the maximum diversity effect across a wide range of higher evenness values. The latter indicates the robustness of the diversity effect to changes in species' relative abundances. 5. Across sites with three complete years of data (24 of the 31 sites), the effect of interactions between the fast-establishing and temporal persistent trait levels of temporal development was highly significant and comparable in magnitude to effects of interactions between N 2 -fixing and nonfixing trait levels of nitrogen acquisition. 6. Synthesis and applications. The design of grassland mixtures is relevant to farm-level strategies to achieve sustainable intensification. Experimental evidence indicated significant yield benefits of four species agronomic mixtures which yielded more than the highest-yielding monoculture at most sites. The results are relevant for agricultural practice and show how grassland mixtures can be designed to improve resource complementarity, increase yields and reduce weed invasion. The yield benefits were robust to considerable changes in the relative propo...

Kirwan, L., Connolly, J., Brophy, C., Baadshaug, O. H., B?langer, G., Black, A., Carnus, T., Collins, R. P., ?op, J., Delgado, I., De Vliegher, A., Elgersma, A., Frankow-Lindberg, B. E., Golinski, P., Grieu, P., Gustavsson, A., Helgad?ttir, ?., H?glind, M., Huguenin-elie, O., J?rgensen, M., Kadziuliene, Z., Lunnan, T., L?scher, A., Kurki, P., Porqueddu, C., Sebastia, M. T., Thumm, U., Walmsley, D. & Finn, J. A. (2014). The Agrodiversity Experiment: three years of data from a multisite study in intensively managed grasslands. Ecology, 95 (9), [2680]Intensively managed grasslands are globally prominent ecosystems. Weinvestigated whether experimental increases in plant diversity in intensively managedgrassland communities can increase their resource use efficiency.This work consisted of a coordinated, continental-scale 33-site experiment. The core designwas 30 plots, representing 15 grassland communities at two seeding densities. The 15communities comprised four monocultures (two grasses and two legumes) and 11 four-speciesmixtures that varied in the relative abundance of the four species at sowing. There were 1028plots in the core experiment, with another 572 plots sown for additional treatments. Sitesfollowed a protocol and employed the same experimental methods with certain plotmanagement factors, such as seeding rates and number of cuts, determined by local practice.The four species used at a site depended on geographical location, but the species were chosenaccording to four functional traits: a fast-establishing grass, a slow-establishing persistentgrass, a fast-establishing legume, and a slow-establishing persistent legume. As the objectivewas to maximize yield for intensive grassland production, the species chosen were all highyieldingagronomic species.The data set contains species-specific biomass measurements (yield per species and of weeds)for all harvests for up to four years at 33 sites. Samples of harvested vegetation were alsoanalyzed for forage quality at 26 sites.These data should be of interest to ecologists studying relationships between diversity andecosystem function and to agronomists interested in sustainable intensification. The largespatial scale of the sites provides opportunity for analyses across spatial (and temporal) scales.The database can also complement existing databases and meta-analyses on biodiversity?ecosystem function relationships in natural communities by focusing on those samerelationships within intensively managed agricultural grasslands.publishersversionPeer reviewe

One of the most important challenges in agriculture is to determine the effectiveness and environmental impact of certain farming practices. The aim of present study was to determine and compare the taxonomic composition of the microbiomes established in soil following long-term exposure (14 years) to a conventional and organic farming systems (CFS and OFS accordingly). Soil from unclared forest next to the fields was used as a control. The analysis was based on RT-PCR and pyrosequencing of 16S rRNA genes of bacteria and archaea. The number of bacteria was significantly lower in CFS than in OFS and woodland. The highest amount of archaea was detected in woodland, whereas the amounts in CFS and OFS were lower and similar. The most common phyla in the soil microbial communities analyzed were Proteobacteria (57.9%), Acidobacteria (16.1%), Actinobacteria (7.9%), Verrucomicrobia (2.0%), Bacteroidetes (2.7%) and Firmicutes (4.8%). Woodland soil differed from croplands in the taxonomic composition of microbial phyla. Croplands were enriched with Proteobacteria (mainly the genus Pseudomonas), while Acidobacteria were detected almost exclusively in woodland soil. The most pronounced differences between the CFS and OFS microbiomes were found within the genus Pseudomonas, which significantly (p<0,05) increased its number in CFS soil compared to OFS. Other differences in microbiomes of cropping systems concerned minor taxa. A higher relative abundance of bacteria belonging to the families Oxalobacteriaceae, Koribacteriaceae, Nakamurellaceae and genera Ralstonia, Paenibacillus and Pedobacter was found in CFS as compared with OFS. On the other hand, microbiomes of OFS were enriched with proteobacteria of the family Comamonadaceae (genera Hylemonella) and Hyphomicrobiaceae, actinobacteria from the family Micrococcaceae, and bacteria of the genera Geobacter, Methylotenera, Rhizobium (mainly Rhizobium leguminosarum) and Clostridium. Thus, the fields under OFS and CFS did not differ greatly for the composition of the microbiome. These results, which were also confirmed by cluster analysis, indicated that microbial communities in the field soil do not necessarily differ largely between conventional and organic farming systems.

Summary Increased species diversity promotes ecosystem function; however, the dynamics of multi‐species grassland systems over time and their role in sustaining higher yields generated by increased diversity are still poorly understood. We investigated the development of species’ relative abundances in grassland mixtures over 3 years to identify drivers of diversity change and their links to yield diversity effects. A continental‐scale field experiment was conducted at 31 sites using 11 different four‐species mixtures each sown at two seed abundances. The four species consisted of two grasses and two legumes, of which one was fast establishing and the other temporally persistent. We modelled the dynamics of the four‐species mixtures, and tested associations with diversity effects on yield. We found that species’ dynamics were primarily driven by differences in the relative growth rates (RGRs) of competing species, and secondarily by density dependence and climate. The temporally persistent grass species typically had the highest RGRs and hence became dominant over time. Density dependence sometimes induced stabilising processes on the dominant species and inhibited shifts to monoculture. Legumes persisted at most sites at low or medium abundances and persistence was improved at sites with higher annual minimum temperature. Significant diversity effects were present at the majority of sites in all years and the strength of diversity effects was improved with higher legume abundance in the previous year. Observed diversity effects, when legumes had declined, may be due to (i) important effects of legumes even at low abundance, (ii) interaction between the two grass species or (iii) a store of N because of previous presence of legumes. Synthesis. Alongside major compositional changes driven by RGR differences, diversity effects were observed at most sites, albeit at reduced strength as legumes declined. This evidence strongly supports the sowing of multi‐species mixtures that include legumes over the long‐standing practice of sowing grass monocultures. Careful and strategic selection of the identity of the species used in mixtures is suggested to facilitate the maintenance of species diversity and especially persistence of legumes over time, and to preserve the strength of yield increases associated with diversity.

Red clover (Trifolium pratense L.) is the predominant legume used in northern European agriculture. Official red clover variety trials are conducted by Natural Resources Institute Finland (Luke) to determine the value of field crop varieties. The trials used for the current analysis were conducted in Luke units in southern Finland (Mikkeli) and northern Finland (Ruukki) in two consecutive years. Plant samples for isoflavone analyses were collected from four varieties grown as four replicates and harvested twice during both growing seasons. The four main isoflavones biochanin A, genistein, daidzein and formononetin were analysed using high performance liquid chromatography. Total phytoestrogen content in the varieties varied in the range of 11.2−14.8 mg g-1 dry matter (DM). The variety and the time of harvest had most effect on the isoflavone, especially formononetin, contents of red clover. A more northern growing area and challenging weather conditions were associated with increased isoflavone concentrations.