Increasing plant diversity in agricultural grasslands boosts yields, reducing reliance on fertiliser

Higher plant diversity in agricultural grasslands increases yields with lower inputs of nitrogen fertiliser. Under warmer temperatures, the yield benefits of more diverse grasslands further increase. There are headline results from a landmark study across 26 international sites as part of LegacyNet, and published in Science. 

Sown productive grasslands (used to supply forage for livestock or as a ley in a crop rotation) typically comprise low species diversity. Two widely used grassland practices comprise 1) a single grass species (monoculture) managed with high inputs of synthetic nitrogen fertiliser, and 2) a two-species grass-legume combination that receives lower inputs of nitrogen fertiliser.

Webinar on multi-species mixtures: the Swiss experience

Prof. Andi Luescher presented a webinar on 30th April 2024 as part of the Agroecology Transect project. (website: agroecology-transect.net)

Andi has worked on multi-species grasslands for many years, and shared his group's research experience that ranges from basic research to on-farm assessments. 

Andi's webinar is available here on YouTube.

Multi-species grasslands enhanced diversity of soil nematode community

New research from the Teagasc Environment Research Centre, Johnstown Castle shows that higher plant diversity of intensively managed multi-species swards enhances belowground soil biodiversity and health. The study, which has been published in the international scientific journal, ‘European Journal of Soil Biology’, showed that as grasslands increased plant diversity up to six species of grasses, clovers and herbs, soil-dwelling nematode communities also had increased diversity and improved performance across a range of ecological soil health indices.

Plant diversity (and drought) affect legacy effects on soil fertility

We investigated the effect of grassland diversity, drought and higher nitrogen level on legacy effects. Legacy effects (measured as yield of a follow-on crop, which reflect the influence of the preceding crop) were strongly positively affected by the proportion of legumes. Drought can impact legacy effects, but is modest relative to the effect of plant diversity. Aggregated across both ley and follow-on crop phases, the high-diversity, lower-nitrogen grassland community yielded more than the higher-nitrogen grass monoculture. 

Fig. 1. Overhead shot of the field site with the experimental design and plot management to track the effect of plant diversity, drought and fertiliser level on the legacy effect within plots.

Assessing the habitat quality of Irish field margins

 

We developed a methodology to assess the habitat quality of field margins in a set of more intensively managed farms in Ireland. Overall, we found that over half of the field margins surveyed had low or very low levels of habitat quality.

Field margin with very low habitat quality (dominated by negative indicator species)

Semi-natural habitats and Ecological Focus Areas on Irish farmland

HIighlights: We surveyed farmland habitats on tillage and more intensive beef and dairy farms. Habitat area was lower than that found in the general countryside, and was dominated by linear features (especially hedgerows). All tillage farms and the majority of pastoral farms in our sample met the current 5% EFA requirement, and the vast majority (93%) met a scenario with a 7% EFA requirement. There is a considerable amount of a broader range of wildlife habitats already present on intensively managed farms that was not included in EFA in Ireland, and is not reflected in policy or legislation. 

Open Access data: landscape classification of Ireland

The FarmForBio project has developed a landscape classification map of the Republic of Ireland. 

The map and the GIS data are now available on Teagasc’s TStor repository https://t-stor.teagasc.ie/handle/11019/2790

Lower nitrous oxide emissions intensity from multi-species swards

Recent Teagasc research shows that multispecies grasslands can potentially reduce both nitrous oxide (N₂O) emissions and emissions intensities, and can contribute to more sustainable grassland production. Greenhouse gas measurements carried out by Saoirse Cummins showed that the annual greenhouse gas emissions per unit output (DM yield or biomass N) from the multi-species mixture were lower than those from perennial ryegrass receiving either 150 or 300 kg ha^-1 yr^-1 of inorganic nitrogen (N).

Webinar: piloting a biodiversity indicator in the Teagasc National Farm Survey

As part of the EU SmartAgriHubs project, Teagasc is investigating how to incorporate biodiversity into the Teagasc National Farm Survey. In a recent webinar, I presented the first results from the application of a habitat index to a sample of 300 farms in the NFS. 

Multi-species swards: more forage with less fertiliser, and more resilient to drought

Based on a Teagasc press release from August 2021

Six-species swards outperformed perennial ryegrass monocultures and were considerably more resistant to drought. New research from Teagasc, Johnstown Castle and Trinity College Dublin shows that multi-species mixtures receiving 150 kg/ha/year of nitrogen fertiliser, out-yielded perennial ryegrass monocultures receiving double that amount of fertiliser (300 kg/ha/year). Increases in plant diversity up to six species in intensively managed grasslands reduced the impact of drought, and produced more yield with less fertiliser.

6-species swards from dairy grazing system at Teagasc, Johnstown Castle. 

Our research on multi-species mixtures at British Grassland Society

The British Grassland Society's 13th Research Conference addressed 'Multi-species Swards' on 2-4 March 2021. Here are links to some of our contributions to the conference, including an invited presentation, a research presentation and a poster. 

CAP4Nature Report

 

This link opens a report from an Irish workshop to solicit biodiversity scientists' opinions as part of an EU series of workshops requested to address the topic 'The Common Agricultural Policy post-2020: A new Green Architecture, Novel Eco-schemes and biodiversity indicators. How can scientists and science help to make it work?' 

Multi-species swards: links to webinars

 

This post lists some webinars and videos on multi-species swards that our research group has contributed to. 

Multi-species grassland mixtures: some recent Irish research

Multi-species mixtures are expected to benefit grassland production because of the yield advantage from nitrogen fixed by clover, the variety of rooting structures allows them to access a wider range of soil water and nutrients, and their canopy structure that allows them to intercept more sunlight. In addition, they are associated with lower parasite loads in livestock, reduced greenhouse emissions, and increased carbon sequestration. Here, we give a brief overview of some of our current (2020) research on mixtures at Teagasc, Johnstown Castle.

Our recent online webinars on biodiversity

As part of Virtual Beef Week (July 8th), there is an online presentation and interview with the Farmer's Journal on biodiversity policy, videos of on-farm practices to improve farmland biodiversity, and interviews with farmers implementing these practices as part of the BRIDE EIP. Also discussion of habitat quantity, quality and results-based payments. With myself, Catherine Keena and Daire Ó hUallacháin of Teagasc. (From 8.17 to 30 mins in the video.)

Teagasc Research Insights Webinars Dec 16th, 2020. In this talk, I give an overview of some of our research on the extent and distribution of farmland habitats at a national and farm scale. I also introduce results-based payments for delivery of biodiversity improvements. (From 1.30 to 19 mins in the video). 

In this webinar as part of the Burren Winterage School (Oct 2020), I discuss some of the principles of results-based approaches for biodiversity conservation. This is illustrated with examples from Irish projects, programmes and case studies that have been applying results-based approaches. It's only fitting that we presented our work back to the Winterage School, as this is where we first committed to publish the book of case studies on results-based payments! (From 30.50 to 54 min). 

In a recent youtube video about multi-species grassland mixtures by DLF, see Guylain Grange and Saoirse Cummins (Teagasc, Johnstown Castle) talk about their research (from 4.09 minutes), amid related research ongoing at UCD and WIT. 

Grassland conservation options in AEOS from a results-based perspective

In a 2017 post, we outlined the main results from a publication (Ó hUallacháin et al., 2016) that compared the vegetation in three different options for grassland conservation under the Irish agri-environment scheme (Agri-Environment Option Scheme, AEOS). Here, we outline the main results of that study, and develop it further with a more detailed interpretation of that work from the perspective of results-based approaches. Across the three grassland options in that study, the options had the effect of preferentially enrolling and financially rewarding lower-quality vegetation. We show how a results-based approach could better target, incentivise and reward the provision of higher-quality vegetation, and make a greater contribution to biodiversity conservation.

SmartAgriHubs: pilot incorporation of farmland habitats in Teagasc National Farm Survey

Teagasc is investigating how to incorporate biodiversity into ~300 participant farms in the Teagasc National Farm Survey. This is being piloted as part of the EU SmartAgriHubs project, which focuses on digital innovation in the agrifood sector. Here, I briefly describe why biodiversity should be included in sustainability assessment, the aims of the pilot project and our methodology, and its potential contribution to improving biodiversity monitoring in farmland.

Report: Independent evaluation of environmental effects of GLAS

The Green Low-Carbon Agri-Environment Scheme (GLAS) has been the Agri-Environment Scheme in Ireland over the RDP period 2014-2020. GLAS. A report from summer 2020 provides an evaluation of GLAS by an independent environmental consultancy. The report is available on the DAFM website here: Evaluation of the Green Low-Carbon Agri-Environment Scheme (GLAS): Synthesis of evidence, and includes an Executive Summary and list of recommendations in addition to the main report. 

Methodology to include farmland habitats in sustainability assessments

A new Teagasc publication to be published in the Irish Journal of Agricultural and Food Research outlines the development of scalable methods to include farmland habitats in sustainability assessments. Here, I give a brief 'taster' of the content of that paper, and an overview of the approach that is based on categorising farmland habitats using satellite imagery. 

 

Farming for Nature: the role of Results-Based Payments 

A new book published by Teagasc and the National Parks and Wildlife Service (NPWS) (www.teagasc.ie/farmingfornature) highlights several Irish case studies of results-based payments for biodiversity conservation.