Organic matter in size fractions of soils of the semiarid Argentina. Effects of climate, soil texture and management

Long-Term Effects of Residue Management on Soil Fertility in Mediterranean Olive Grove: Simulating Carbon Sequestration with RothC Model

“…Similar results have been reported by Castro et al (2008). According to Hevia et al (2003) the NFOM presented high correlations with the clay content only in the soils UC (Figure 4). This showed that the addition of plant debris and other residues with high carbon content alter the relation between SOC and the fine-size particle.…”

“…The content of the SOC was determined using the method of Tyurin (1951); water-floatable organic matter (FOM) and non-water-floatable organic matter (NFOM) was separated following the method described by Hevia et al (2003); for the total nitrogen, the Kjeldahl method was used (Bremner, 1965); and the CaCO 3 equivalent was determined by a manometric method (Williams, 1948). For plant remains, carbon and N were determined by the same methods.…”

“…Some authors recommend methods to separate the water-floatable organic matter (FOM) from soil fractions according to size, using physical procedures such as ultrasound, together with a mixture of physical and chemical methods (Buyanovsky et al, 1994;Hevia et al, 2003). These latter procedures of fractionation appear to be more adequate when the residues added provide certain quantities of soil together with the plant debris.…”

Assessment of soil particle redistribution on two contrasting cultivated hillslopes

“…The study by Gerzabek et al (2001) compared the average C contribution of particle-size fractions to the total amount and revealed the following: ranking: silt (63-2 Am) N clay (2-0.1 Am) N fine clay (b0.1 Am) N fine sand (200-63 Am) N coarse sand (2000-200 Am). Jolivet et al (2003) and Hevia et al (2003) also found soil organic matter correlated positively with clay + silt contents. Jolivet et al (2003) further found that organic matter in the clay + silt fraction was relatively resistant to degradation after 30 years of cultivation and that the protective capacity of the soil depended on the proportion of clay + silt fraction, which stabilized the organic matter.…”

"Técnicas espectroscópicas aplicadas à análise da matéria orgânica do solo em pomares de citros sob adição de lodo de esgoto"

“…8 É assumido na literatura que o valor da razão E 4 /E 6 é inversamente proporcional a massa molecular, assim uma alta razão E 4 /E 6 infere uma massa molecular baixa, além disso baixo grau de condensação aromática, e consequentemente, a presença de proporções relativamente altas de cadeias laterais. Segundo alguns autores 58,102 a razão E 4 /E 6 pode ser utilizada como uma forma de estimar a aromaticidade, sendo que quanto menor a razão E 4 /E 6 maior é o grau de aromaticidade das SH.…”