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Assessing Indices for Predicting Potential Nitrogen Mineralization in Soils under Different Management Systems
Author(s) -
Schomberg Harry H.,
Wietholter Sirio,
Griffin Timothy S.,
Reeves D. Wayne,
Cabrera Miguel L.,
Fisher Dwight S.,
Endale Dinku M.,
Novak Jeff M.,
Balkcom Kip S.,
Raper Randy L.,
Kitchen Newell R.,
Locke Martin A.,
Potter Kenneth N.,
Schwartz Robert C.,
Truman Clinton C.,
Tyler Don D.
Publication year - 2009
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/sssaj2008.0303
Subject(s) - soil water , mineralization (soil science) , linear regression , tillage , mathematics , zoology , chemistry , nitrogen , mineralogy , soil science , statistics , environmental science , ecology , biology , organic chemistry
A reliable laboratory index of N availability would be useful for making N recommendations, but no single approach has received broad acceptance across a wide range of soils. We compared several indices over a range of soil conditions to test the possibility of combining indices for predicting potentially mineralizable N (N 0 ). Soils (0–5 and 5–15 cm) from nine tillage studies across the southern USA were used in the evaluations. Long‐term incubation data were fit to a first‐order exponential equation to determine N 0 , k (mineralization rate), and N 0 * (N 0 estimated with a fixed k equal to 0.054 wk −1 ). Out of 13 indices, five [total C (TC), total N (TN), N mineralized by hot KCl (Hot_N), anaerobic N (Ana_N), and N mineralized in 24 d (Nmin_24)] were strongly correlated to N 0 ( r > 0.85) and had linear regressions with r 2 > 0.60. None of the indices were good predictors of k Correlations between indices and N 0 * improved compared with N 0 , ranging from r = 0.90 to 0.95. Total N and flush of CO 2 determined after 3 d (Fl_CO2) produced the best multiple regression for predicting N 0 ( R 2 = 0.85) while the best combination for predicting N 0 * ( R 2 = 0.94) included TN, Fl_CO2 , Cold_N, and NaOH_N. Combining indices appears promising for predicting potentially mineralizable N, and because TN and Fl_CO2 are rapid and simple, this approach could be easily adopted by soil testing laboratories.