Soil degradation is one of the world’s great environmental problems. At the same time as rivers are contaminated with sediments eroded from soils, severe erosion in many parts of the world results in a significant decrease in soil productivity. Although the immediate cause for water erosion may be intense rainfall, there are a number of reasons soil loss is especially severe in some situations. Susceptibility to erosion is influenced by soil type (silts are more susceptible), degree of aggregate stability, and extent of soil cover by residue and/or growing plants. Compaction, another form of soil degradation, can go unnoticed unless one looks for the symptoms, but it can have a damaging effect on plant growth. For a discussion of tried and true ways of reducing erosion and compaction, see chapters 14 and 15. And for how to reclaim saline, sodic, and saline-sodic soils, see chapter 20.


da Silva, A.P., B.D. Kay, and E. Perfect. 1994. Characterization of the least limiting water range of soils. Soil Science Society ofAmerica Journal 58: 1775–1781.

Letey, J. 1985. Relationship between soil physical properties and crop production. Advances in Soil Science 1: 277–294. Ontario Ministry of Agriculture, Food, and Rural Affairs (OMA-FRA). 1997. Soil Management. Best Management Practices Series. Available from the Ontario Federation of Agriculture, Toronto, Ontario, Canada.

Soehne, W. 1958. Fundamentals of pressure distribution and soil compaction under tractor tires. Agricultural Engineering 39: 276–290.

Tull, J. 1733. The horse-hoeing husbandry: Or an essay on theprinciples of tillage and vegetation. Printed by A. Rhames, for R. Gunne, G. Risk, G. Ewing, W. Smith, & Smith and Bruce, Booksellers. Available online through the Core Historical Literature of Agriculture, Albert R. Mann Library, Cornell University,

Unger, P.W., and T.C. Kaspar. 1994. Soil compaction and root growth: A review. Agronomy Journal 86: 759–766.