In:
Soil Science Society of America Journal, Wiley, Vol. 54, No. 3 ( 1990-05), p. 775-780
Abstract:
Anhydrous NH 3 applied to soil is subject to chemical fixation by organic matter. A laboratory study was conducted to (i) determine the amount of N retained through chemical fixation of NH 3 compared with the amount of NH 4 fixed by clay, (ii) characterize the organic‐matter‐fixed NH 3 , and (iii) assess the biological availability of the fixed NH 3 . Nitrogen‐15 labeled liquid anhydrous NH 3 was injected into a Drummer silty clay loam soil (2.07 g NH 3 ‐N kg −1 soil), and the fixed 15 NH 3 ‐N was characterized by sequential extraction with Na 4 P 2 O 7 , KOH, NaOH, and dimethyl sulfoxide (DMSO). About 16% of the 15 NH 3 ‐N injected was fixed by the soil. Of the N fixed, 48% was accounted for by chemical fixation into the soil organic fraction, most of which was removed by sequential extraction, and 52% was accounted for as clay‐fixed NH 4 . Of the organic‐matter‐fixed 15 NH 3 ‐N, 55% was recovered in the fulvic acid (FA) fraction obtained by sequential extraction with Na 4 P 2 O 7 and KOH; about equal amounts (17%) were recovered in the humic acid (HA) and humin fractions. The remainder (11%) was recovered in the NaOH and DMSO extracts. Most of the fixed 15 NH 3 ‐N in the FA fraction was recovered as either low‐molecular‐weight (LMW) fraction or nonhumic substances. The availability of the fixed 15 NH 3 ‐N (occurring as either organic‐matter‐fixed NH 3 or clay‐fixed NH 4 ) to soil microorganisms was estimated to be 13% after incubation with glucose for 7 d; from 20 to 22% was found to be potentially available to plants as estimated by distillation with MgO. Results indicate that NH 3 ‐N newly fixed by organic matter occurs in forms that are less stabilized and more biologically available than the native soil N.
Type of Medium:
Online Resource
ISSN:
0361-5995
,
1435-0661
DOI:
10.2136/sssaj1990.03615995005400030025x
Language:
English
Publisher:
Wiley
Publication Date:
1990
detail.hit.zdb_id:
241415-6
detail.hit.zdb_id:
2239747-4
detail.hit.zdb_id:
196788-5
detail.hit.zdb_id:
1481691-X
SSG:
13
SSG:
21
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