SOILS

~Presented by The Natural Resource Conservation Service (U.S.) & Whatcom Conservation District

Only one-third (1/3) of the earth's 200 million square miles is land. Less than half of this land is suited for the production of food and fiber.

The world's population is increasing at a rapid pace but the amount of land we have is constant. More and more people are becoming dependent on this limited acreage for their food. For this reason we all need to take great interest in the land and do all we can to make certain that each acre of land is put to its best use and used within its capabilities.

There are over 10,000 different types of soil in the United States. Some of these soils are deep and fertile and are capable of allowing almost unlimited plant growth. Others are very shallow and plant growth is severely restricted. Some soils are well suited for home building while others are too wet, or too steep, or too unstable to support the weight of a house.

Building a house on unstable soils could be disastrous since the house might shift and actually break apart. Building on good farm land could also be disastrous since the land would be lost for food production. On the other hand, trying to grow crops on poor land is impractical since the yield would be low and the soil might be damaged by erosion.

The soil forming process is extremely slow. It takes several thousands years for nature to build enough soil to adequately support plant life. Soil can be damaged or lost through misuse or by erosion in a short time. Therefore, we must treat soil carefully, understand soils limitations and take the necessary steps to conserve it.

During the Field Trip We Will Learn:

1. What a soil is and what makes up soil.
2. How soils are formed. How this particular forest soil was formed.
3. How and why soils differ.
4. How different soils have different capabilities and limitations.
5. Some concepts on classifying soils.
6. What a soil survey is and how the information found in a survey helps people.

The specific soil type at the Soils Station is 157 - Squalicum gravelly loam, 15 to 30 percent slopes. Utilizing your copy of the Whatcom County Soil Survey please work with the students to identify the specific characteristics and limitations, described in the lesson, for Squalicum gravelly loam.

Notes:

1. SOIL
   A mixture of minerals, organic matter, air and water on the earth's surface that is capable of supporting plant life.

2. SOILS ARE MADE UP OF

   1. Mineral matter (45%), rock fragments, sand, silt, and clay.

   2. Organic matter (5%), (both living and dead); animals - worms, insects, rodents, etc. plants - roots, stems, leaves, bacteria, fungus

   3. Water (25%)

   4. Air (25%) (within the pore space).

3. SOILS ARE FORMED BY
   1. Weathering of rocks and materials (parent material)

      1. Chemical Weathering: the affect of water, acids and minerals in solution acting on rock to cause chemical decomposition (breakdown) into smaller particles.

      2. Mechanical Weathering: the influence of temperature, plants, water, ice and wind on soil causing destruction of rock fragments.

   2. Movement and Deposition of Material:

      1. by water, wind and gravity.

4. ALL SOILS ARE NOT THE SAME
   The physical characteristics of soil is influenced by the environmental conditions under which it formed. Environmental factors include:

   1. Type of parent material

   2. Climate (temperature and rainfall)

   3. Vegetation

   4. Topography (relief, drainage patterns, aspect)

   5. Length of time for soil formation and weathering processes.

5. SOIL TYPES CAN BE DETERMINED BY FIELD EXAMINATION OF SOIL
   By grouping them according to similar properties (texture, depth, color, wetness, slope, etc.)
6. IT IS IMPORTANT TO KNOW ABOUT SOIL TYPES

   1. To determine best use of land.

   2. To know the limiting factors of soil.

   3. To know what is needed to protect the soil.