Soil air

A part of the soil volume that is not occupied by soil particles, known as pore space, is filled partly with soil water and partly with soil air. As the pore space is occupied by both water and air, volume…

Soil water

Soil water is the major component of the soil in relation to the plant growth. The water is held within the soil pores. If the moisture content of a soil is optimum for plant growth, plants can readily absorb the…

Organic matter

Soil organic matter represents partially decayed and partially synthesized plant and animal residues. Such material is continually being broken down by the action of soil microorganism. Consequently, organic matter is a transitory soil constituent and renewed constantly by the addition…

Mineral matter

The minerals are extremely variable in size. Some are as large as the smaller rock fragments; others, such as colloidal clay particles, are so small that they cannot be seen without the aid of an electron microscope. Quartz and some…

Water in the soil

There are three forms of water occurring in soil. Hygroscopic water is unavailable to plants because it is physically bound to soil particles. Gravitational water is the water that drains from pore spaces after rain. Plant growth can be affected if drainage is poor. Capillary…

Soil structure

Soil structure refers to aggregates. Aggregates are formed as a result of the arrangement and grouping of soil particles. Sand and gravel aggregates do not demonstrate cohesion very well. In most good agricultural soils, aggregates that stick together form readily. The…

Mineral composition and soil texture

The size of the individual soil particles is called soil texture. The three general designations are sand, silt, and clay. Generally, sands and gravels are composed of many small particles bound together chemically or by a matrix of cementing material. Silt…

Local area topography

Topography refers to the surface features of an area. For example, if an area is a steep soil that is weathered from parent material may quickly wash away or erode through the actions of wind, ice, and water. On the…