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The estimation of mineralization, immobilization and nitrification in nitrogen‐15 field experiments using computer simulation
Author(s) -
BARRACLOUGH D.,
SMITH M. J.
Publication year - 1987
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1987.tb02287.x
Subject(s) - nitrification , mineralization (soil science) , nitrogen , ammonium , nitrate , nitrogen cycle , chemistry , lysimeter , environmental chemistry , agronomy , environmental science , soil water , soil science , biology , organic chemistry
SUMMARY A combination of mathematical analysis and computer simulation, using parameters readily measured in a nitrogen‐15 field experiment, is employed to determine rates of mineralization, immobilization and nitrification under a growing crop. The procedure also yields the proportion of crop nitrogen uptake occurring as ammonium and nitrate. When applied to ‐results from grass lysimeters receiving 250 or 900 kg N ha –1 a –1 as ammonium nitrate, the analysis suggested that at 250 kgN ha –1 a –1 64–66% of crop nitrogen uptake was as ammonium; at 900 kg N ha –1 a –1 the figure was 43–49%. Nitrification at 250kgNha –1 was only 13–19kgN ha –1 over 160d while at 900 kg N ha –1 between 191 and 232 kg N ha –1 were nitrified. The results suggested that the apparent inhibition of nitrification in grassland soils may simply reflect poor substrate competition by nitrifying bacteria. Finally, there was a suggestion that mineralization/immobilization was lower at the high fertilizer rate.