Soil Ecological Risks of Increased Use of Lignocellulose

Lignocellulose constitutes the largest input of organic carbon into soils. Through decomposition, lignocellulose along with other organic molecules becomes soil organic matter (SOM), a crucial factor in soil physicochemical dynamics and quality. However, SOM differs in terms of lignin content and composition. How lignin - the most common phenolic compound in soil - controls SOM properties and soil functions is unknown.

In this project, the direct influence of lignin and its decomposition products on central soil properties will be quantified. We hypothesize that the lignin content of organic matter ameliorates soil physicochemical and biological properties in addition to the quantity. Removal of lignocellulosic biomass from forest ecosystems would therefore be detrimental to soil quality.

Relations between cupric oxide (CuO) oxidation lignin markers and characteristic soil properties will be checked through an inventory of eight Fagus sylvatica (L.) forests in southwestern Germany and quantitative analysis along transects of increasing lignin content. Cation exchange capacity, acid neutralization capacity, pH, water holding capacity, SOM occlusion in aggregates, aggregate stability, and fungal diversity are the properties of interest. Analysis of CuO-oxidized lignin will be done at Martin Luther University Halle-Wittenberg.

Planned research following the previous steps include lignin in agricultural and plantation soils and the development of a bioindicator method for lignin content based on fungi. Ultimately limiting removal of lignocellulose to safeguard soil as well as ways to improve agricultural soil quality will be addressed.