Abstract

The sequestration of organic matter (OM) in soil is an important issue in relation to soil quality and the cycling of carbon on a global scale. Most OM sequestered in soil is associated within the microstructure (Hassink and Whitmore 1997), defined here as the microaggregates within the soil fraction <20µm. Factors that may influence the amount of OM sequestered in these microaggregates include soil conditions (wetting and drying cycles, salts, pH, temperature and time), nature of the soil particles, and the sequence of interactions between these particles.

A fundamental approach has been used to study the factors that affect the process of microaggregation of particles in soils, by creating soil microaggregates under controlled laboratory conditions using well characterised soil components (Varadachari et al. 1997). Formation of these aggregates in the presence of soluble OM demonstrates how OM may be bound by or occluded within microaggregates. Aggregation processes between various types of OM (tannic acid and humic acid) and soil mineral particles (bentonite and kaolinite) are included in the initial investigation.

These results will be useful for enhancing the understanding of the more complex processes that occur in soils in the natural environment, in relation to land and soil management practices and carbon sequestered in soil.

References

Hassink, J. and Whitmore, A. P. (1997) Soil Science Society of America Journal, 61, 131-139.

Varadachari, C., Chattopadhyay, T. and Ghosh, K. (1997) Soil Science, 162, 28-34.