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Multi-species grassland swards enhance soil biology

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.  

Soil nematodes are often used as indicators of soil health and ecosystem functioning. Compared to monocultures of forage plants, multi-species grasslands with six species had a higher abundance of predatory nematodes, which can be beneficial for the biocontrol for plant pests. Conversely, there was a lower abundance of herbivorous nematodes in multi-species grasslands, the presence of which can negatively affect plant performance. 

Nematodes are tiny round worms that are widely distributed and highly abundant in soils. They play important roles in the health of soil systems, especially for nutrient and carbon cycling. They are sensitive to changes in the environment and can give an indication of multiple aspects of the soil food web and ecosystem health. Several nematode-based soil quality indices are available that relate to soil function, making them especially attractive as a soil biodiversity indicator.  

Lead author on the study, and former postdoctoral researcher with Teagasc, Dr Israel Ikoyi, stated; “This study shows that even for intensively managed grasslands, the use of multi-species forage mixtures that include grasses, legumes, and herbs can have a positive effect on the soil nematode community and nematode-based soil quality indices. This can lead to improved nutrient cycling, decomposition, and plant growth, which can have important implications for the overall health and function of the soil ecosystem. This is an important finding linking aboveground plant diversity with belowground soil biodiversity.”  

Dr Fiona Brennan, Soil Microbiologist with Teagasc said; “Plant-soil interactions are incredibly important for the maintenance of below ground soil biodiversity, and play a key role in the functioning and resilience of soil systems. Diversifying plant communities can create more habitats in soil, which in turn supports more diverse soil biological communities. These communities are essential for soil and plant health, underpinning food production and playing a critical role in regulating climate. As international efforts to safeguard our soils intensify, this paper contributes to the scientific evidence available to underpin policy and practical management advice.”  

Biodiversity and farmland ecology researcher with Teagasc, Dr John Finn said; “We have already seen benefits of plant diversity in multi-species swards for attributes such as forage production with lower nitrogen, weed suppression, livestock performance and drought resilience. This latest research reveals additional positive effects of multi-species swards on belowground soil biodiversity.”  

See the published scientific paper at: https://www.sciencedirect.com/science/article/pii/S116455632300078X  

This work was funded by the EU Horizon research and innovation programme under the MASTER project (grant agreement No. 818368), and Teagasc Walsh Scholarships Programme.