Simulation by NCSOIL of Net Mineralization in Soils from the Deherain and 36 Parcelles Fields at Grignon

Abstract
Soil N and C mineralization was measured from the Deherain and 36 Parcelles fields at the experimental station of Grignon, France. In the Deherain plots, manure and inorganic N effects have been compared on a wheat‐sugarbeet rotation since 1875. In the 36 Parcelles field, the effect of composted straw and inorganic N on the soil organic matter have been studied since 1959 on bare plots. Control plots without any organic or inorganic additions were maintained in both fields. In cultivated and bare plots, rates of C mineralization were similar when soils had been organically amended (farm manure or composted straw). The addition of inorganic N increased the soil total organic N and C content in comparison to the respective control plots, but it did not change the rates of N and C mineralization. Net N mineralization was linear and the determination of potentially net mineralizable N (No) as the asymptotic value of an exponential kinetic gave aberrant values. A new approach to measure No was proposed using the model NCSOIL which simultaneously simulates N and C dynamics in soil. The No was quantified as the initial N content of the model's pool I plus pool II which represent the soil active organic matter involved in N and C turnover.