Biodegradation of some organic materials in soils and soil constructions: Experiments, modeling and prevention

The decomposition of natural and synthetic polymeric materials (peat, humates, biochar, strongly swelling hydrogels and other soil conditioners) in a biologically and chemically active soil environment inevitably leads to a reduced ability to improve the structure, water-retention, absorptive capacity and fertility of artificial soil constructions in urbanized ecosystems and agro landscapes (constructozems). Quantitative assessment of the biodegradation process using field and laboratory incubation experiments, as well as mathematical modeling, showed the possibility of significant (up to 30-50% per year) losses of organic matter of constructozems and a corresponding deterioration of soil quality. Incubation experiments that track the carbon dioxide emission rates of polymeric materials under given thermodynamic conditions allow for the estimation of decomposition rates in addition to an exploration on the dependence of such rates on additions of microbial inhibitors. The use of nomographs provide an opportunity to optimize long-term amendment performance in soil constructions by identifying the most favorable depths to apply amendments to ensure stable functioning during desired in-service timelines in the built environment. The results of the study are useful for geo-engineers and landscaping practitioners. © 2018 by the authors