The Influence of Organic Matter on Soil Aggregation and Water Infiltration

The unimpeded flow of water down through the soil is essential to agricultural production. Intensive cultivation can disrupt soil structure and restrict infiltration, which results in inefficient water and land use. In this review, the effects of organic matter on soil aggregation and water infiltration are discussed at several levels. Organic amendments (manure, plant residue, and synthetic polymers) are reported to increase soil organic matter (fulvic acids, humic acids, and polysaccharides) which binds soil particles together into aggregates. When soil structure is improved through aggregation, the resulting pore size distribution favors the downward flow of water in soil (infiltration). Mechanisms that link these components (e.g., organic amendments, polysaccharide production, aggregate formation, and increased infiltration) are suggested and management options that improve water infiltration rates are proposed.