Bound phenolic acids in humus fractions of andosols under varying vegetation in the sierra Nevada, Mexico

• Published in: Geoderma 1991-05, Vol.48 (3), p.431-442
• Main Authors: Drijber, Rhae A., Lowe, L.E.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/0016-7061(91)90058-2

Humic acid (HA) and a polyphenolic fraction of fulvic acid (FP) were isolated from Ah horizons of soils in three climax vegetation zones on the flanks of the volcanco Iztaccihuatl in central Mexico. The three zones were dominated by Abies religiosa (lowest zone), Pinus hartwegii, and an alpine grassland community (at highest elevation) referred to as Zacatonal. The Pinus zone has an open stand of trees with grass groundcover. Molecular weight distribution and elemental composition were determined for HA and FP fractions. Only minor differences between zones were observed. In contrast, HA were consistently higher in N and S than the FP. Hydrolysis of HA and FP released protocatechuic acid, P-hydroxybenzoic acid, vanillic acid, and syringic acid. The ratios of these phenolic acids clearly differed among vegetation zones. The differences were attributed to characteristic differences in the lignin in other polyphenolic constituents of the vegetation.