soil productivity is generally associated with poor nutrient status and the physical condition of the soil, but the effect of soil mineralogy on soil productivity has received little attention. in this qualitative study, interactions between mineralogy and physico-chemistry and their role on the productivity of two luvisols, an arenosol and a vertisol are investigated. minerals identified in th...

Radiocarbon data from soil organic matter and soil respiration provide powerful constraints for determining carbon dynamics and thereby the magnitude and timing of soil carbon response to global change. In this paper, data from three sites representing well-drained soils in boreal, temperate, and tropical forests are used to illustrate the methods for using radiocarbon to determine the turnover...

Tillage has been reported to reduce organic matter concentrations and increase organic matter turnover rates to a variable extent. The change of soil climate and the incorporation of aboveground C inputs within the soil lead to no unique effect on biodegradation rates, because of their strong interaction with the regional climate and the soil physical properties. The periodical perturbation of ...

Recent improvements in our understanding of the dynamics of soil carbon have shown that 20-40% of the approximately 1,500 Pg of C stored as organic matter in the upper meter of soils has turnover times of centuries or less. This fast-cycling organic matter is largely comprised of undecomposed plant material and hydrolyzable components associated with mineral surfaces. Turnover times of fast-cyc...

Organic matter in soil has been suggested to be composed of a complex mixture of identifiable biopolymers rather than a chemically complex humic material. Despite the importance of the spatial arrangement of organic matter forms in soil, its characterization has been hampered by the lack of a method for analysis at fine scales. X-ray spectromicroscopy has enabled the identification of spatial v...

Soil physical structure causes differential accessibility of soil organic carbon (SOC) to decomposer organisms and is an important determinant of SOC storage and turnover. Techniques for physical fractionation of soil organic matter in conjunction with isotopic analyses (dC, dN) of those soil fractions have been used previously to (a) determine where organic C is stored relative to aggregate st...

Organic farming systems still depend on intensive, mechanical soil tillage. Frequent passes by machinery traffic cause substantial soil compaction that threatens soil health. Adopting practices as reduced tillage and organic matter retention on the soil surface are considered effective ways to control soil compaction. In tropical regions, however, the acceleration of soil organic matter decompo...

Rates of oxygen uptake, sulphate reduction, carbon dioxide production, ammonium turnover, nitrogen fixation and denitrification were measured in sediments in a transect across a mangrove swamp in Jamaica. Carbon and nitrogen mineralisation increased as the transect entered the mangrove, indicating a greater availability of organic matter, probably by root excretion. Time course measurements of ...