Comparison of a novel model to three conventional models describing carbon mineralization from soil amended with organic residues

Abstract

The decomposition of organic soil amendments is a dynamic process that is not fully understood at present. Carbon mineralization by soil microorganisms has been modeled to derive useful theoretical parameters regarding the decomposition process. This paper compares a new model describing carbon mineralization from amended soil to three others commonly used in the literature. Carbon dioxide evolution from soil amended with five rates of an alkaline-stabilized biosolid (0, 2.08, 4.16, 8.32, and 12.48 mg/g d.w.) was monitored using alkali traps sampled on days 0, 3, 6, 9, 12, 15, 22, 29, 45, 55, 71, 88, 103 and 121. The new model, a first order exponential plus logistic function (FLOG), is based on the recognition of different competitive strategies (the r– K continuum) in the soil environment. The FLOG model performs better than the first order and first order plus linear models for all amendment rates except the control. A double first order model produced a lower mean square error for all treatments but had non-normal residuals in one case. The FLOG model performs comparably well against other common models, and can generate curves ranging from almost exponential in appearance to curves containing inflection points, a feature not possible in combined exponential and/or linear models. Further investigation into the biological significance of the new parameters may be beneficial in describing the decomposition process, such as linking the timing of the delayed pool to changes in soil enzyme activities, shifts in microbial community composition, or aspects of the nitrogen cycle for example.