Soils

Soil is one of the most important natural resources. We use soil for everything. We use it to grow our food, we use it for fuel and we use it to build homes. It is important that we understand the soil that we build, design, work, and grow on. When we understand the soil we can work to preserve and protect it.

There are many definitions of soil. Soil is the loose surface of the earth made up of materials that provide nutrients for plants. Soil is made up of a mixture of mineral matter, organic matter, water and air. Soil is everything in the ground between the common rooting depths of plants to the air.

A soils depth ranges from place to place. It could be just a few inches thick up to many kilometers thick. The NRCS gives five soil forming factors that alter soil material: climate, time, relief, organisms and parent material. Soil is formed through translocations, transformations, additions, and losses. When these interactions happen the result is many combinations giving us the variety of soils we have today. No two solid are just alike but they are similar. The similar soils are grouped together for classification.

The soil profile is the sequence of layers of the soils from the surface down. Soils in different places in the world are formed by different factors and different environments. Soils in Kansas have very different soil profiles that soils in Australia.

The soil profile is made up of layers called horizons. The thickness of horizons vary but they are usually parallel with the earth’s surface. Weathering of soil starts at the top and goes down so the most changed soil is the top layer and the deeper layers are more original to the parent material. Sometimes soil horizons stand out but other times it is hard to se...

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... clay loam, clay loam, silty clay loam, silty clay, sandy clay and clay.

Structure is the arrangement of soil particles. Structure is classified into various classes. Structureless, including single grain and massive, with structure including granular, platy, wedge, blocky, prismatic, and columnar. The last class is structure destroyed which includes puddled.

The weight of oven dried soil is referred to as bulk density. It is determined by dividing the soil into grams by its volume in cubic centimeters. Finer textured soils have higher percentages of total pore space, therefore it has smaller bulk density.

Soil color helps people recognize different soil types, it also indicates physical and chemical characteristics. Two factors create color in soils, humus content and iron compounds. Humus makes the soil dark and iron can give soil a gray, red, or yellow color.