European Union Directives stipulate a reduction in nitrate levels in groundwater. Digital techniques developed by researchers at the TUM School of Life Sciences Weihenstephan under the aegis of the Technical University of Munich (TUM) have proved useful in achieving this goal.
Up until now, farmers have calculated the amount of fertilizer per field on the basis of average yield and average soil quality. However, soil properties, yield potential and fertilizer needs may vary within limited areas, even within a single field. In places that deviate from the field’s mean, plants therefore receive too much or too little fertilizer. Excess nitrogen remains in the soil, accumulating over the years and eventually escaping into the environment, for example into the groundwater.
Professor Kurt-Jürgen Hülsbergen , chair of Organic Agriculture and Agronomy, is certain: "The fertilizer needs of crop plants will increasingly be calculated using sensor-based systems and fertilization algorithms."
Over the past two decades, Hülsbergen and his team have established a digital nutrient management system based on long-term field experiments. This system is used to analyse, evaluate and optimize the material and energy flows of agricultural production. Research carried out by Hülsbergen’s lab member Dr. Franz-Xaver Maidl usefully complements the opportunities afforded by precision fertilization. Maidl has developed a sensor-based system and algorithms for site-specific nitrogen fertilization.
Hülsbergen’s lab thus provides two digital instruments that help farmers save fertilizer and reduce the burden on the environment. A three-year research project starting now in January 2020 will subject these to extensive testing on a site located in Upper Bavaria (Burghausen / Burgkirchen) before making them available to agricultural practice and consultancy.
Hülsbergen’s team has developed a modular, web-based management system that is now being tested on regional model sites such as Burghausen/Burgkirchen. This enables farmers not only to precisely determine the nutrient and fertilizer needs of their plants, but also to optimize fertilizer distribution under crop rotation. The system can be used in both organic and conventional farming. The aim is to increase nitrogen efficiency and reduce environmentally relevant nitrogen emissions.
"A suitable fertilization algorithm ensures that farmers do not suffer any yield losses and that society benefits from high water quality," explains Hülsbergen.
One of the powerful tools for precision fertilization is a special multispectral sensor that can be attached to the tractor. It measures the light reflected by the crop. The reflection can then be used to calculate the nitrogen nutritional status of the plants.
The system also takes account of the growth stage, soil quality and the desired product quality, and then calculates the optimum amount of fertiliser to be applied. This means that a single operation is enough to measure the current nitrogen content of the plant and to adjust the level of fertilizer applied in real time.