Increasing agricultural nutrient-use efficiency by optimizing plant-soil-microorganism interactions
Project number: 031A561A-G
Contact: Prof. Dr. N. Brüggemann, Research Center Jülich GmbH, Helmholtz Association
Project team: Free University of Berlin, Helmholtz center in Munich, Universität zu Köln, Universität Kiel, Leuphana University Lüneburg, Nürtingen-Geislingen University of Economy and Environment, Institute of Energy and Environmental Science Heidelberg
Duration: 01/04/2015 - 31/05/2024
Excessive fertilizer use in agriculture leads to nutrient imbalances, which are the cause of nutrient losses leading to surface and groundwater pollution as well as increased greenhouse gas emissions. A sustainable agriculture has to find ways to minimize this nutrient inefficiency, while maintaining or even increasing crop productivity and quality. Motivation is the development of novel plant cultivation strategies directed towards “engineering” the complex nutrient cycling interactions between plants and soil microorganisms, combined with improved timing of fertilizer and soil amendment applications.
This interdisciplinary project supports the knowledge-based evaluation of potentials to optimize plant-microbial interactions and to improve the nutrient-use efficiency in agricultural crop production. The evaluation and characterization of these interactions directly supports the development of new agricultural management strategies to reduce nutrient losses and environmental pollution.
The synthesized knowledge helps to maintain and improve the soil functions and services of agricultural cropping systems even at regional scale.
Results from phase 1
The first phase showed that agricultural management has a decisive influence on the composition and functionality of the soil microbiome.
Furthermore, it could be shown that C:N:P stoichiometry plays an important role for N-binding and N-turnover in soil, and thus could play an important role in plant-microbial competition for nutrients.
The field trial demonstrated that N surpluses after winter oilseed rape and faba bean can be effectively bound with wheat straw and sawdust with a high C:N ratio, but that this bound nitrogen is not completely available in the following year, but predominantly only in the year after.
The socio-economic analysis showed that a widespread use of wheat straw and sawdust to bind N surpluses in agriculture would compete with alternative utilisation paths, in particular bioenergetic use.
Results from phase 2
We demonstrated that organic soil amendments with high organic carbon content (HCA) cause significant N immobilization. Molecular data from Phase II clearly indicate that the soil microbiome is strongly affected by the addition of HCA, sometimes the effect was even greater than those of seasonal variation. We demonstrated that the microorganisms affected by management are not the same ones that respond to seasonal fluctuations. HCA-mediated microbial changes in soil could have a positive effect on soil C sequestration rates and on the nutrient immobilization capacity of the soil microbial biomass, leading to a reduction in N losses during non-vegetation periods.
Expected results phase 3
In Phase III, we will further investigate the dynamics of N remineralization under field conditions for different soil types and climatic conditions, especially under the influence of drought, to be able to optimize application recommendations for HCA. We will also focus on the effects of HCA addition on the composition and functions of plant-associated microbial communities involved in the drought stress response of plants. Since these responses can vary depending on the location, experiments will be conducted at different long-term trial sites in Germany with different soil types and climatic conditions.