The influence of agricultural management practices on microbial functions and networks in biological soil crusts

• Applicant: Dr. Stefanie Schulz
• Subject Area: Soil Sciences ; Microbial Ecology and Applied Microbiology
• Term: from 2016 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 321601720

As the world population is continuously increasing, it is estimated that food production must be doubled by the year 2050. Therefore, an increase in crop yield connected with a sustainable management system is needed. The diversity of arable land and their connected characteristics is high. In Germany the arable assessment rating (Ackerzahl) revealed values from 100 (highly fertile) to less than 30 (very low fertility). Especially soils with a low Ackerzahl are prone to erosion due to their unfavourable texture. In those soils the establishment of biological soil crusts (BSC) during the vegetation free period displays an advantage for crop growth. This is due to the key functions of BSC, which are the fixation and turnover of nitrogen and carbon and the excretion of EPS, which increase soil nutrient content and soil stability in their direct vicinity. Due to those positive effects of BSC on soil properties, there is a need to understand the impact of land use management on the establishment and functioning of BSC in low fertility agricultural fields. Therefore, it is the aim of this project to analyse the microbial composition and function in BSC from an arable field trial with an initially very low assessment rating (25-30). In a multifactorial design the influence of nitrogen fertilization, organic fertilization and tillage regime will be analysed with respect to the microbial EPS production, which is strongly connected to C input by organic fertilization and microbial nitrogen turnover, which in turn is affected by the amount of added mineral fertilizer. Furthermore, the analyses will focus on bacterial, archaeal and fungal key players and networks. As for example a good collaboration between fungi and bacteria might improve the transport of bacteria to subsoil areas via fungal highways. To assess changes in the overall bacterial, archaeal and fungal abundance and network composition BSC samples from the different treatments will be quantified by quantitative real-time PCR and characterised by using the MiSeq technology. To characterise the functions of the involved microbial key players a metagenomic approach will be applied with a special focus on nitrogen and exopolysaccharide (EPS) turnover. The obtained molecular data will be connected with soil chemical analyses and the composition of EPS.

• DFG Programme: Research Grants