SOILS The primary ingredient in successful gardening is ideal garden soil. Without good soil, tools might as well hang in the shed and seeds, plants and supplies remain at the garden center. Phrases like "black gold" and "alive soil" are common in discussions of good garden soil. Although these phrases may sound strange, they come from scientific concepts about soil. Black gold is a common reference to humus. Soils that contain humus often have many live organisms. Lack of respect for the soil shown by past civilizations has often permanently changed the land. Conversely, the land and soil have changed the forms and patterns of civilization. Soil has affected civilization in many ways: types of crops grown, length of time people spent farming a particular area and farming techniques used. It has destroyed or preserved whole civilizations. Improper soil usage relates to many of our present global environmental problems. This chapter reveals why good garden soil is an important factor in plant health. Master Gardeners must be educated "stewards of the soil." Knowledgeable gardeners know how to improve soil to their benefit. They know the "recipes" for ideal garden soil.
KEY CONCEPTS SOILS I. Soil Composition II. Soil Horizons III. Soil Formation IV. Soil Characteristics V. Soil Modifications Return to Introduction		SOILS To appreciate what soil is all about, good gardeners must spend time working in it. Digging is the best way to learn about soil. Digging exposes the soil's texture, "crumb" size, and how quickly it dries. Digging shows the progression from dark color at the top into strong colors of deeper mineral layers. Tunnels of worms (sometimes down as far as 5 feet) are seen.   SOIL COMPOSITION The composition of garden soil may be surprising to some. Soil consists of not only solid mineral particles, but also of decaying organisms, living organisms, air and water. Specifically, soil is composed of the following: - mineral matter - sand, silt and clay or nonliving material from rock - microbes - bacteria, fungi and algae - animals - worms, insects, snakes, mammals - organic matter - decaying matter that was once alive (plants, animals and microbes) - pore space - open spaces occupied by air or water Ideal garden soil contains the above ingredients in the following amounts:   SOIL HORIZONS SOIL HORIZONS are individual horizontal layers seen by exposing a vertical cross section of soil. Driving through the countryside where roads cut through hills, the traveler sees distinct layers of soil. Every soil profile includes the following horizons: A horizon - the "living layer," often called "topsoil." It is dark due to organic matter. This is the coarsest, most fertile layer where most roots grow. B horizon - the second layer often called "subsoil" made of more COMPACTED material. It contains finer particles. Brighter in color, it is often nutrient rich but low in organic content. It stores water. C and R horizon - the parent soil material and rock native to the locale. This layer determines natural fertility, pH, and soil depth. The oldest rocks exposed in the state are found in southwestern Ohio. This parent material is interbedded shales and limestones deposited on the bottom of a warm, shallow sea over 400 million years ago. Much of the rest of the state, except for the hill southeastern quarter is influenced by parent material deposited by glaciers. These areas have a rich, silty clay soil. The soil in the unglaciated southeastern section of Ohio is form the underlying shale and sandstone bedrock. The resulting soil is generally more acidic and less fertile.   SOIL FORMATION Soil is a natural product of the environment. Native soils form from the parent material by action of climate (temperature, wind and water), native vegetation and microbes. The shape of the land surface affects soil formation. It is also affected by the time it took for climate, vegetation and microbes to create the soil. [diagram factors affecting soil formation]
Introduction | Botany | Soils and Fertilizers | Entomology and Pest Management | Plant Pathology | Plant Propagation | Houseplants | Lawns | Herbaceous Ornamentals | Woody Ornamentals | Vegetables | Herbs | Fruit | Glossary