Influence of Prescribed Burning on Nitrogen Mineralization and Nitrification in Grassland

Abstract

The seasonal dynamics of gross nitrogen (N) mineralization, nitrification, and mineral nitrogen consumption rates were studied with the 15N pool dilute technique in burned and unburned Leymus chinensis (Trin.) Tzvel. (Chinese Wildryegrass) grasslands. Gross N mineralization is the gross rate of the process of the conversion of organic N to the form during decomposition before N immobilization by microbes. Similarly, gross nitrification is the gross rate of the conversion of and organic N to before N immobilization by microbes, and consumption is sum of mineral N losses by biological or nonbiological processes. Results indicated that gross mineralization and nitrification rates, and consumption rates, and soil concentrations of were higher in burned grassland areas than in unburned areas in April and May and that all were lower or similar compared to unburned areas in September. The soil concentrations of indicated no difference between burned and unburned areas in April and May, but burned areas had higher in July and September. Results indicate that prescribed burning in spring could benefit the renewal of grasslands of northeast China through mobilization of soil N pools.