Kinetic analysis of the decomposition and mineralization of plant residuesin gray forest soil

Dynamics of the decomposition of N-15-labeled corn roots and aboveground or gans (leaves and stems) incorporated in gray forest soil were studied. Kine tic parameters (C-max, N-max, k(C), k(N), and T-0.5) were derived from the approximation of different segments of the cumulative curves of C-CO2 produ ction, inclusion of N-15 into microbial biomass, and the 15N content in the total soil nitrogen by linear regression equations. Based on these paramet ers, three fractions of organic matter characterized by rapid, average, and slow carbon mineralization and nitrogen cycling were distinguished. It was emphasized that carbon and nitrogen from these fractions composed a minera lizable pool of these elements in soils; its size significantly increased d ue to the decomposable plant material. It was shown that the content of mic robial biomass in the soil and the efficiency of utilization of carbon-cont aining substrates by microorganisms could be determined from the kinetics o f their mineralization.