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Soil organic matter factions of no-tilled and tilled soils and their reactivity with herbicides

Thesis/Dissertation ·
OSTI ID:6157376
Properties of soil humic fractions were determined on surface and 7.5-15.0 cm soil samples of continuously (7-year) no-tilled and tilled cotton, corn, and soybean plots in West Tennessee. Soil humic and fulvic acid were extracted by standard methods and the humic acid was characterized by /sup 13/C-NMR spectroscopy, titration of total acidity and carboxyl groups, and infrared and elemental analysis. Humic acid composition differed by depth and crop. Small differences were observed between tillage systems. Humic acid aliphatic and aromatic carbons ranged from 48 to 65% and 25 to 40% of total peak area, respectively. The humic acids extracted from soils with larger amounts of carbon had larger aliphatic to aromatic ratios, indicating less decomposed organic matter. Carboxyl groups of the humic acids ranged from 9 to 13% and samples from tilled soil had slightly greater amounts of carboxyl and aromatic groups. Carboxyl group determinations by /sup 13/C-NMR, compared more closely with total acidity determinations by titration than with carboxyl determinations by titration. All infrared spectra were similar. Elemental composition of humic acid averaged C, 52.7%, 5.6%; N, 4.8%, and 36.9%.
Research Organization:
Tennessee Univ., Knoxville (USA)
OSTI ID:
6157376
Country of Publication:
United States
Language:
English