Fertiliser placement and application of fertilizers and plant protectants by drip irrigation (fertigation) are approaches with the aim to reduce inputs of fertilisers, water, pesticides and labour by localised application of fertilisers close to the root system of crops. Several mineral nutrients, such as phosphate, nitrate and ammonium are able to stimulate root growth for exploitation of nutrient-rich patches. Therefore, fertiliser placement close to crop roots is expected to reduce nutrient competition with other plants. However, under real agricultural production conditions, intense localized root proliferation is not frequently observed. This may be attributed to the absence of steep nutrient concentration gradients in many agricultural soils due comparatively high background concentrations of nutrients even outside the local patch of fertilisers. Therefore, WP07 investigates perspectives to increase the efficiency of crops to exploit fertilizer patches by application of bio-effectors with the ability to stimulate root growth. Additionally also the possibility to use fertilizers based on organic or inorganic waste recycling products for fertilizer placement will be tested including options to integrate bio-effectors for improved nutrient solubilisation within the fertilizer patches (link to WP06). Fertiliser depots are frequently characterized by high local salt concentrations and pH extremes to be tolerated by microbial bio-effectors selected for application in fertilizer placement strategies (link to WP04).
