Aggregate formation in soil. 1. Influence of some bacterial polysaccharides on the binding of soil particles

Abstract

For maximum crop production it is essential that the soil should have a good crumb structure and that the crumbs should be stable and resistant to the dis- persing effects of rain, frost, etc. Aggregate formation facilitates cultivation, drainage and aeration, increases the moisture-holding capacity of soil and reduces erosion. It also maintains sufficient cohesion in the soil to give anchorage to plants, and yet suffi- cient incoherence to facilitate root penetration and emergence of seedlings. Large additions of organic matter and the growth of grassland vegetation are credited with having an ameliorative effect on the physical state of the soil, but there is considerable diversity of opinion as to the exact processes in- volved in the formation of water-stable aggregates.