Impact of Grassland Management in Microbial Communities and Soil Structure.

Soil ecosystems are amongst the most diverse environmental systems on Earth. The biology found in a gram of soil contains more than ten thousand individual species of bacteria and fungi. Soil biodiversity is considered the driver of many critical processes that support ecosystem services such as; nutrient mineralisation, plant production, water purification and regulation and carbon cycling. The variety of the microbial community is supported by soil structure, which represents the habitat for all the processes occurring in the soil. Nevertheless, soil structure is a key component of soil quality and is influenced by soil biology. The aim of our work is to deeply investigate the mutual effect between microbial community and soil structure quality. For this purpose, land management needs to be appropriately studied to understand whether and how it drives soil biological processes, structure quality and related functions. A land use intensity index (LUI) was built using management information collected through a farmer questionnaire. The questionnaire was run at 38 grassland farms distributed in the five major agro-climatic regions of Ireland, assessing all the common farming practices. The questionnaire was summarised into 3 management intensity components: (i) Fertilisation (Fi), (ii) Mowing (Mi) and (iii) Livestock Grazing (Gi). Sites were sampled to assess the impact of land management intensity on microbial community structure and activity. Soil structure data were collected through a combined approach of visual evaluation methods and quantitative measurements. Initial findings indicate that the LUI components are efficient metrics to assess the influence of management in microbial populations. Microbial community structure and activity was highly affected by intensive grassland management, showed by Fi and Mi indexes. The LUI was unable to explain changes in soil structure quality. However, the effect of management indicates that microbial population has an indirect but strong influence in improving soil quality.