Procedures for the Isolation and Fractionation of Humic Substances

Hayes, M.H.B.; Graham, C.L.

doi:10.1016/b978-1-85573-807-2.50012-6

Cited by 14 publications

(9 citation statements)

References 26 publications

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“…Moreover, isolation of humic substances from soil has always been a challenge task for researchers, even during last years (Silveira et al 2008;Stevenson 1994;Sparks 1995;Hayes and Graham 2000;Dai et al 2006;Shirshova et al 2006). Furthermore, recently some authors (Miralles et al 2009) has been pointed out that some soils (such as old forest and those located at the uppermost areas of the mountain system) could be considered as representative for the highest levels of soil quality because of their favourable physical and chemical properties exclusively associated to the high concentration of organic matter.…”

Section: Introductionmentioning

confidence: 97%

Degradability of soils under oak and pine in Central Spain

2009

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The purpose of this research was to study the influence of the vegetation on the soil C pool of forests of pines (Pinus sylvestris) and oaks (Quercus pyrenaica), located in Central-Western Spain. Horizons from selected soils located in these forests were sampled, and the soil organic C (SOC) was determined. In addition, in vitro incubation experiments were carried out, under controlled conditions, to monitor the stability of SOC against the microbial activity. Soil humus fractions were isolated following a classical procedure of chemical fractionation using alkaline solutions, before and after the incubation experiment. A deeper O horizon was found under the pine forest than under oak one; however, higher SOC content was found in the oak site than that under pine one. During the in vitro mineralization process, a lower CO 2 production by the soil sample from pine forest was observed, in relation to that emitted by the oak soil. In addition, a lower humification degree was estimated for the soil humus under pines than for that under oaks. In conclusion, replacement of oaks by pines produced a decrease in SOC accumulation and a lower quality of humus in the forest soils.

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Section: Introductionmentioning

confidence: 97%

Degradability of soils under oak and pine in Central Spain

2009

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“…These compounds are major sinks of refractory organic carbon and their resistance to microbial degradation is attributable to self-associations of the molecules through associations with difficult-to-degrade substances, such as longchain hydrocarbons in fatty acid and esters, to associations with the soil's mineral colloids and to entrapment in soil aggregates. HS play an important role in soil conservation, for water holding capacity, and for the complexation of metals in terrestrial and aquatic systems (Stevenson, 1994;Swift, 1996;Hayes and Malcolm, 2001;Hayes and Graham, 2000).…”

Section: Introductionmentioning

confidence: 98%

Multimethod study of the degree of humification of humic substances extracted from different tropical soil profiles in Brazil's Amazonian region

et al. 2005

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“…Isolation of humic substances (HSs) from soil has always been a challenging task for researchers (Kononova, 1966;Orlov, 1990;Stevenson, 1994;Sparks, 1995;Hayes and Graham, 2000). The highest HS yields are usually obtained by the classical isolation procedure including aqueous alkaline solution extraction after a pre-treatment of the soil sample with dilute aqueous acid.…”

Section: Introductionmentioning

confidence: 99%

“…At the same time mild extractants such as sodium pyrophosphate, cation exchange resins, etc., tend to give significantly lower HS yields than do alkaline solutions (Levesque and Schnitzer, 1967;Kononova and Alexandrova, 1973;Rosell et al, 1981;Hayes, 1985;Shirshova, 1991a). As a compromise, a sequential extraction procedure has been proposed, where it is the mild extractants that initiate the HSs isolation process with alkaline conditions following in the wake (Shirshova, 1991a,b;Hayes and Graham, 2000).…”

Section: Introductionmentioning

confidence: 99%