Soil Properties

What is Soil? Is the top layer of the Earth’s surface suitable for the growth of plant life.

The Soil Profile Soil Horizon Soil Profile They are the layers of the different types of soil found at different depths in the soil profile. Soil Profile A vertical section through the soil extending into the unweathered parent materials and exposing all the horizons.

Master Horizons Are the A, B and C horizons. Typically found in most soils They are a part of a system for naming soil horizons in which each layer is identified by a code O, A, E, B, C & R.

The Horizons The O Horizon The organic layer made of wholly or partially decayed plant material and animal debris. Normally found in a forest with fallen leaves, branches and other debris.

The Horizons The A Horizon Also called the topsoil. The most fertile layer of soil. Contains the most organic matter. Usually the top or first layer.

The Horizons The E Horizon Also called the layer of eluviation. This is the zone of the greatest leaching of clay, chemicals and organic matter.

The Horizons The B Horizon Also called the subsoil. Called the zone of accumulation where chemicals leached out of the A horizon. Reason why most subsoil has an increase in clay content.

The Horizons The C Horizon Called the parent material. Lacks the properties of the A & B horizon. Less touched by soil forming processes.

The Horizons R Horizon Is the underlying bedrock such as…. Limestone Sandstone Granite

Soil Profiles

Soil Texture Refers to the size of particles. Three types are…. Sand (Large) Silt (Medium) Clay (Small)

Relative Size of Soil Particles

Soil Texture - Sandy The largest of the soil particles. Individual particles can be seen with the naked eye. Low moisture-holding capacity.

Soil Texture - Loamy About equal parts of…. Sand Silt Clay Ideal texture for most non-container outside plants.

Soil Texture - Clayey The smallest of the soil particles. Clay particles stick to one another. Has a high water-holding capacity.

Textural Classes There are 12 textural classes. Represented on the Soil Texture Triangle. Textural class determined by the percentage of sand, silt, & clay.

Soil Structure Refers to the way soil particles cling together to form soil units or aggregates, while leaving pore space to…. Store air. Store water. Store nutrients. Allow root penetration.

Types of Soil Structures There are five types of soil structures. They are: Single grain Granular Platy Blocky Prismatic

Soil Structure – Single Grain Associated with sandy soils.

Soil Structure - Granular Is the best for most plants. Particles cling together to form rounded aggregates. It is commonly found in A horizons. Peds are small usually between 1 to 10 millimeters.

Soil Structure - Platy Usually found in E horizons. Large, thin peds. Plate-like & arranged in overlapping horizontal layers.

Soil Structure - Blocky Particles cling together in angular aggregates. Typical of soils with high clay content. Typical of B horizons. Peds are large about 5 to 50 millimeters.

Soil Structure - Massive Soil has no visible structure. Hard to break apart & appears in very large clods.

Soil Structure More important to producers who grow plants in natural soils because…. Producers of container grown plants add ingredients to make growing media desirable.

Soil Composition About 50% of the soil should be solid particles. 45% - Minerals 5% - Organic Matter About 50% of soil should be pore space. 25% - Air/Pore Space 25% - Water

Soil pH pH has the most impact on the availability of nutrients in the soil/media. pH Scale Ranges from 0 to 15. Indicates the level of acidity or alkalinity. 7 is considered neutral. Everything greater than 7 is considered alkaline (basic). Everything less than 7 is considered acidic.

pH Scale

Ideal pH The ideal pH of most ornamental plants & lawn/turfgrasses is 5.5 to 7.0.

Ph Scale Review What would be a pH of 7.0? What would a Ph pf 3.5 be? Neutral. What would a Ph pf 3.5 be? Acidic. What would a pH of 9.0 be? Alkaline.

Land Capability Based on the physical, chemical, and topographical aspects of the land.

Land Capability Classes Assigning a number to land. Eight classes used. I to VIII with I having the best arability. Class I to IV can be cultivated. V to VIII tend to have high slope or are low & wet.

Land Capability Classes Class I - Very good land. Very few limitations. Deep soil and nearly level. Can be cropped every year as long as land is taken care of. Class II - Good land Has deep soil. May require moderate attention to conservation practices.

Land Capability Classes Class III - moderately good land. Crops must be more carefully selected. Often gently sloping hills. Terraces and strip-cropping are more often used. Class IV - fairly good land. Lowest class cultivated. On hills with more slope than class III. Class V - Unsuited for cultivation. Can be used for pasture crops and cattle grazing, hay crops or tree farming. Often used for wildlife or recreation areas.

Land Capability Classes Class VI - Not suited for row crops. Too much slope. Usually damaged by erosion with gullies. Can be used for trees, wildlife habitat, and recreation. Class VII - Highly unsuited for cultivation. Has severe limitations. Best used for planting trees. Steeply sloping. Large rock surfaces and boulders may be found. Very little soil present.

Land Capability Classes Class VIII – Cannot be use for commercial plants. Cannot be used for row crops or other crops. Often lowland covered with water. Soil maybe wet or high in clay. Best suited for wildlife & recreation.