Microbial bioindicators of soil health and management practices using long-term experiments across Europe

Soil health has been defined as the soil's capacity to support crop growth without becoming degraded. Yet, soil health is under threat by overuse, climate change, salinization, erosion, compaction, nutrient depletion, contamination with toxic heavy metals or pesticides, overgrazing, and human assisted migration of soil-borne pests. Many agricultural practices that are proposed to be sustainable provide relatively small improvements and merely slow down the rate of degradation, which means that soils remain endangered. Thus, not only improvements in soil quality and fertility, but also a restoration of the soil food web, locking-up carbon in soil organic matter, improving water holding capacity, and diminishing soilborne pest outbreaks need to be addressed. To establish a representative database of soil factors changes induced by various agriculture management as well as factors reflecting local soil conditions and climate, seven long term experiments were sampled for physical, chemical and biological soil characteristics. Those include also the community composition and quantity of microorganisms, namely bacteria, archaea and fungi, which seem to be the most promising soil bioindicators. Thus, the main goal of the study was to combine the soil factors representing soil management and relate them to soil microbial communities for estimation of changes in microbial phylogenetic and functional diversity, which will be proposed as indicators of soil health. Since some management practices are replicated within our data set, the selected indicators will be determined using one set of sites and confirmed using another set of sites. The experiment is part of the EJP Soil – MINOTAUR project and covers different regions of Europe, so we anticipate proposing those indicators for agriculture practices as a measure of changes in soil quality and prediction of future soil development.