Describing the mineralization of carbon added to soil in crop residues using second-order kinetics

The kinetics of the production of carbon dioxide from several different, easily-decomposable crop residues was studied in two sand soils, a silty clay loam and a clay soil. In separate experiments sugar beet crowns, sugar beet leaves, a mixture of crowns and leaves, residues from sprouts, leeks, lettuce, spinach or cabbage were added to soil. A second-order rate law was derived and its ability to describe the CO2 production compared with a first-order rate law. The mathematical function derived from second-order kinetics was related to the hyperbolic function. Second-order kinetics proved superior to first-order in most instances not only where the data were accumulated but also where the functions describing C mineralization were adapted to predict discrete data.