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United States Department of Agriculture

Agricultural Research Service

Title: CHARACTERIZATION OF N-15 LABELED HUMIC ACIDS FROM A NITROGEN-TILLAGE- RESIDUE FIELD EXPERIMENT)

Author
item Vial, Ryan
item Clapp, Charles
item Van Patten, Christa
item Brunnetti, Gennaro
item Hayes, Michael
item Mao, Jingdone
item Hormann, Christara
item Molina, Jean

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/21/2001
Publication Date: N/A
Citation:

Interpretive Summary:

Technical Abstract: Soil samples were taken from a Rosemount, MN long-term field experiment where 40 at-% N-15 was applied for 15 yr under N-tillage-residue management treatments. The plots were cropped to corn (Zea mays L.) for 15 yr, followed by 5 yr of soybean [Glycine max (L.) merr.] with no N applied, and then 1 yr of corn before sampling. The samples represented combinations of ftill and no-till, with residue-removed or residue-harvested, at 2 g N m-2 as ammonium sulfate. Humic acids (HAs) were extracted using a modified IHSS method, and isolated by membrane-filtration, precipitated, dialyzed, and freeze-dried. Elemental analyses showed minor differences between HAs, with residue-returned samples having higher C and N values. Differences were also noted between residue-removed and residue-returned treatments, for carbohydrates, amino acids and acidity components. FTIR, fluorescence, and CPMAS 13C-NMR spectra provided valuable characterization and compositional information.

Last Modified: 8/24/2016
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