Soils provide agricultural plants with water and nutrients. The soil living organisms decompose plant and root residues and thus contribute to the exchange of substances in the rhizosphere. Soil fertility is characterized by soil properties such as structure, humus content, water permeability, water holding capacity and nutrient availability. Therefore, these soil properties determine the yield potential of agricultural fields.

Soils are natural bodies formed over long time periods. Depending on the soil type, they consist of specific layers - the soil horizons. Especially the upper soil horizons are subject to continuous change through natural influences and human activities. Weathering, mineralization, decomposition, and humification modify the composition of soils. The soil structure can change by wind and water erosion. Land use and agricultural management have also an impact on soil properties, especially by tillage, crop rotation, and fertilization.

The soil texture of a given soil and with this the soil type are defined by the mineral composition of the soil skeleton (debris and gravel > 2 mm) and finer particle mixtures (silt, clay and sand < 2 mm). Soil organic matter (soil organisms, dead plant and animal matter, humic substances), soil water, soil air, and soil temperature are components that affect soil structure and root growth. The plant availability of macro- and micro-nutrients, the ion exchange capacity, soil reaction and buffering capacity for contaminants are other parameters that can significantly influence the soil functions.

Soil fertility is a dynamic system of interrelations, mainly influenced by natural site-specific factors. Land use, plant growth, soil organisms, climatic and environmental conditions affect the fertility of agricultural soils. To maintain soil fertility it is important to sustain the natural soil functions:

• to serve as medium for plant growth and habitat for soil organisms
• to be the primary resource for production of food and other biomass
• to interact with the environment - water and nutrient cycling, filtering, buffering and immobilizing of environmentally hazardous compounds, carbon pool…  

Within the scope of applied soil science, agriculturally important parameters of soil fertility will be determined and quantified. Research topics are related to soil chemistry, soil physics and soil biology with the aim to support the sustainable agricultural management of agricultural soils.