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Laboratory Methods for Estimating Plant Available Nitrogen in Soil 1
Author(s) -
Ryan J. A.,
Sims J. L.,
Peaslee D. E.
Publication year - 1971
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1971.00021962006300010017x
Subject(s) - sorghum , incubation , soil water , organic matter , nitrogen , chemistry , agronomy , zoology , soil ph , soil organic matter , incubation period , environmental chemistry , biology , ecology , biochemistry , organic chemistry
Biological and chemical methods for obtaining an index of soil N availability to a test crop under different levels of N fertilization were evaluated on 15 Kentucky soils having a range of organic matter contents of 0.72 to 2.79%. Organic matter, N mineralized during aerobic incubation at 30C or 40C for 7 or 14 days, and extractable NH 4 +− ‐ 3 times after incubation under waterlogged conditions for 7 or 14 days at 30C and 14 days at 40C were all significantly related to N uptake and relative increase in N uptake by ‘X‐1605’ grain sorghum ( Sorghum vulgares ) during 18 weeks of growth in the greenhouse. When the soils were amended in the laboratory with P and K or P, K, and Ca and incubated under waterlogged conditions, the relationship between extractable NH 4 +‐ N and N uptake by sorghum improved greatly over unamended soils. Nitrogen mineralized during aerobic incubation and NH 4 +‐ N after incubation of amended soil under waterlogged conditions were among the better predictors of both N uptake and relative increase in N uptake.