Autor:innen:
Ryan Bartnick | Soil Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany | Germany
Aileen Jakobs | Ecological Microbiology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany | Germany
Prof. Tillman Lüders | Ecological Microbiology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany | Germany
Prof. Eva Lehndorff | Soil Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany | Germany
Microplastic (MP) interactions in the soil are not well studied and limitations exist to analyze the diverse array of MPs in soil. Microplastics have been observed to have an impact on soil chemistry, soil structure, water storage, and microbial communities. We hypothesized that MP introduction in soil will cause changes in (a) physical properties: reduce stable aggregate formation and water holding capacity, and (b) chemical properties: reduce carbon and nutrient storage, and (c) biological properties: reduced plant nutrition and shift in microbial community.
To better understand the effect of MPs on soil physical, chemical, and biological properties, Zea mays was planted in pots with two soil types (sandy and silty) and spiked with three MP types (PE, PET, PBAT) and separated by three concentrations (0%, 0.1%, 1% w/w) and three MP size ranges (200-400 µm, 75-200 µm, < 75 µm); additionally, controls of plants potted with no MP and addition of sand instead of microplastic were sampled. Aggregate fractionation and stability, along with water holding capacity, were tested to see changes in physical structure of the soil and rhizosphere. To understand chemical interaction and nutrient cycling, 15N-labelled ammonium nitrate and 13C-yeast as representative of organic matter were added to soil to observe changes in plant uptake, nutrient pools, and soil organic matter mineralization. Biological changes to plant growth, root biomass and leaf area index were assessed, and microbial community composition will be investigated.
We expect overall effect of MPs to be greater in silty soil compared to sandy soil and with higher concentrations of MP. In more detail, we assume that specifically the small MP size will disturb soil aggregate formation and that this will lead to a destabilization and loss of soil organic matter (represented by 13C-yeast C). The decay of biodegradable plastic (PBAT) is expected to change soil chemistry such as pH and nutrient sorption more than in treatments with conventional MP. Shifts in microbial community should be more pronounced in the presence of biodegradable PBAT compared to soil amended with PE and PET. This study is meant to highlight the role of conventional and biodegradable plastics on critical soil functions such as the storage of water and carbon as well as on nutrient retention and plant nutrition. Such disturbances might have serious implication for soils under drought stress in the during climate warming.