Environmental Engineering Reference
In-Depth Information
Loam
is an even mixture of sand, silt, and clay particles. Generally, loamy soils with a pH close to neutral are
ideal for agricultural plant growth because of their ability to retain water and nutrients.
Source: U.S. Department of Agriculture
pH
The pH scale measures hydrogen ion concentrations on a scale of 1 to 14. Acidic substances range from 1 to
6.9, and alkaline (or basic) substances range from 7.1 to 14; a pH of 7 is neutral. Soils that are acidic lack nutri-
ents, and alkaline soils can contain an excess of sodium. In general, agricultural soils are best in the range of 3
to 7.
Soil characteristics and properties vary from place to place depending on temperature and precipitation. Hu-
man activities are having a profound impact on soils globally because of deforestation, nutrient depletion,
overgrazing, overuse, and ultimately erosion. Human effects on soil are reviewed in Chapter 4.
