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Estimates of Potentially Mineralizable Soil Nitrogen Based on Short‐Term Incubations
Author(s) -
Stanford George,
Carter J. N.,
Smith S. J.
Publication year - 1974
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/sssaj1974.03615995003800010031x
Subject(s) - mineralization (soil science) , soil water , incubation , nitrogen , chemistry , nitrogen cycle , environmental chemistry , zoology , mineralogy , soil science , geology , biology , biochemistry , organic chemistry
Nitrogen mineralization potentials were determined for a large number of soils by a method involving determination of N mineralized after several consecutive incubations at 35C under optimum soil water conditions. The determination of N mineralization potential, N o , based on the first‐order equation, log (N o − N t ) = log N o − kt /2.303, is laborious and usually requires incubation periods of 8 weeks or more. From the present study, involving soils from major agricultural areas throughout the United States, it was demonstrated that N o could be estimated reliably from the amounts of N mineralized during 2‐week incubations following preliminary incubations of 1 to 2 weeks. From the above first‐order equation, N o = N t /(1–10 ‐ kt /2.303 ). Hence, for a 2‐week incubation ( t = 2), N o = 9.77N t (N t = N mineralized in 2 weeks and k is the rate constant, weeks ‐1 ). Estimates of N o from short‐term incubations were similar to those derived after extensive periods of incubation. Preincubation of soils is required in order to decompose plant residues and for other possible reasons noted. Estimates of N o from preliminary incubations are meaningless. The implications of N o as a basis for predicting amounts of soil N mineralized under fluctuating temperature and soil water conditions are discussed.