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Kinetic Analysis of Net Nitrogen Mineralization in Soil
Author(s) -
Juma N. G.,
Paul E. A.,
Mary B.
Publication year - 1984
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1984.03615995004800040011x
Subject(s) - mineralization (soil science) , nonlinear regression , loam , soil water , mathematics , chemistry , zoology , soil science , regression analysis , statistics , environmental science , biology
Studies were conducted to determine the most suitable mathematical equation and the most appropriate method for calculating the values of the parameters of the equation describing the net N mineralization in soil. The cumulative net N mineralized in two treatments of a 15 N labeled soil and five unlabeled Saskatchewan soils showed curvilinear trends that could be fitted to either hyperbolic or first order equations. The kinetic parameters of the hyperbolic equation, 15 N H 0 (potentially mineralizable N) and T c (time required for 1/2 N H 0 to mineralize) determined by nonlinear least squares (NLLS) yielded the best fit to the data for the labeled soil and had the lowest RMS error. Linear regression (1/N vs 1/ t ) yielded 15 N H 0 and T c values which were markedly different than those obtained with the N vs. N/ t and t /N vs. t transformations or those obtained with the NLLS method when all the data were considered. The double reciprocal plot gave undue weight to the initial data points. The 15 N H 0 estimated by NLLS method accounted for 62 and 72% of the total organic 15 N remaining in the two treatments of Weirdale loam soil. The N H 0 for Saskatchewan soils ranged from 51 to 429 µg N g −1 soil, while the T c ranged from 7.3 to 45.8 weeks. The 15 N F 0 values obtained with the first order equation using NLLS method accounted for 39 to 44% of the total organic 15 N remaining in soil. The N F 0 values for Saskatchewan soils ranged from 35 to 255 µg N g −1 soil while the values of net mineralization rate constant, k , ranged from 0.036 to 0.164 weeks −1 . Both equations accurately predicted the amount of net N mineralized over 14 weeks incubation. However, the estimates of potentially mineralizable N and mineralizable N half‐life were dependent upon the model used.