Motivation
Rising populations worldwide demand greater efforts to meet the resulting demand for food in a socially and environmentally compatible and sustainable manner. This is a major challenge, because in Germany and around the world, the amount of land available for arable farming is steadily decreasing and the risk of crop failures during warm and dry summers is increasing, while the availability of fertilizers is decreasing or the costs for them are rising.
Until now, it has been greatly underestimated that large stocks of water, carbon and nutrients lie in the subsoil, although plants cover 10-80% of their nutrient and water requirements from the subsoil. The latter could help to secure yields and increase productivity, especially in dry years or under nutrient deficiencies. So far, however, the subsoil has hardly been considered in management strategies. The aim of the Sustainable Subsoil Management (Soil3) project is to include the subsoil in management options. We hypothesize that water and nutrient uptake from the subsoil can be increased if attractive conditions are generated for the crop to invest in root growth in the subsoil. This can be accomplished through measures such as reducing physical resistance for the root, creating nutrient hotspots in the subsoil, or storing water in the subsoil when the topsoil dries out due to seasonal conditions.
Within the joint project Soil3, the following measures are used: a) in a combination of deep-rooting precultures with mechanical techniques, the soil chemical, physical and biological properties of the subsoil are to be improved for plant growth. Here, the subsoil is heterogenized with a trencher and organic material is incorporated into the subsoil. In addition, b) an inventory and analysis of metadata from long-term field trials and data from the German Soil Inventory - Agriculture will provide information on nutrient conditions in the subsoil. This will enable us to test concretely, and also from the point of view of technical feasibility and socio-economic acceptance, how the total soil volume can be optimized for agricultural use.
