Models for Predicting Potentially Mineralizable Nitrogen and Decomposition Rate Constants

Abstract

Abstract Two equations, a single exponential: N t = N o (1 − e ‐kt ) and a double exponential: N t = N o S (1 − e ‐kt ) + N o (1 − S )(1 − e ‐kt ), were used to compare mineralization potentials of soils, where N t is the N mineralized in time ( t ), N o is the potentially mineralizable N, and S and (1 − S ) are the fractions of the labile and recalcitrant organic N compounds decomposing at specific rates h and k , respectively. Data were obtained from the published and unpublished incubation studies of Stanford and Smith (MD), Smith et al. (WA), Deans et al. (MN), El‐Haris et al. (US), and Griffin and Laine (CT). The double exponential equation provided the “best fit” of the N mineralization‐time (N t / t ) curve as determined by the estimated mean square error (MSE). With long‐term (>84 d) incubations, N t / t curves for the double exponential equation resulted in an avg MSE of 6 compared with the single exponential equation (avg MSE of 79) for CT, MN, and MD data sets ( n = 20). For short‐term (≤84 d) incubations, N t / t curves were better estimated by the double exponential (avg MSE = 4, n = 21) than by the single exponential (avg MSE = 12, n = 13) for WA, US, and MN data.