ANALYSIS OF SOIL-NITROGEN MINERALIZATION AS ESTIMATED BY EXPONENTIAL MODELS

The simple and the double exponential models used to describe the soil N mineralization process were analyzed by using a central finite differences approximation. Various investigators have found that these models show deficiencies in estimating the mineralization N pools. This paper investigates the possible causes or such deficiencies. The mineralization rate was observed to decrease continuously as the N mineralization proceeds. As long as the incubation time became greater, the estimated size of the mineralizable N pool was larger and the estimated mineralization rate became smaller. These results suggested that the exponential models did not conform to the actual N mineralization process and that the assumption of the existence of discrete size pools of mineralizable N is a faulty concept. © 1990.