Don’t Judge a Soil by It’s Label! Never look gift soil in the label! What is in a soil? Don’t count your plants before they germinate!

After this lesson the student will be able to: 1.Describe the components of soil. 2. List the components of a soilless mix. 3. Compare and contrast the use of soil versus a soilless mix.

Terms Clay Inorganic Loam Mineral matter Organic matter Pasteurization Peat Moss Perlite Sand Silt Soil Soil Amendment Soilless Mix Sterilization Vermiculite

What is Soil? Soil – outer layer of the earth that supports life. Recipe for Soil –1cu. Air –1cu. Water –1 4/5 cu. Mineral matter –1 tbl. organic matter –Mix thoroughly and let stand.

Understanding Properties of Growing Media When asked what plants need to grow, most people would respond with water, sunlight, and soil. In all actuality, soil is only one of the media that could be used to grow plants. There are a number of substances that would allow plants to grow.

Soil is the outer portion of the Earth’s crust that supports plant growth. A Soilless medium (one that contains no topsoil) can be used to grow plants.

A relatively new method of growing plants is within a hydroponics unit. Hydroponics is a method of growing plants in a nutrient solution. The plants in a hydroponics unit could be supported in a sand or gravel substrate for support or the roots could be left bare. With bare roots, the plants’ root system can float in the nutrient rich solution, or the nutrients could be sprayed directly onto the roots.

No matter what choice of media is used, all growing medium (the material in which the roots of plants grow) has to achieve certain functions. Growing medium needs to provide nutrients to the plants. The nutrients are needed by the plants for growth and flower and fruit production.

Growing media must also provide a place for the roots to anchor themselves. Plant roots are fragile and are crucial to a plant’s successful growth. If the media helps hold the plants, the plant is less likely to fall over or move about, ripping the root system.

Aeration (the presence of oxygen) is another important characteristic of growing medium. Plants need oxygen in order to make their own food. Plant roots also need to be able to breathe. The oxygen in the media is located in the pore spaces between the particles of the of media. The pore spaces are the air holes between the particles.

Growing media must also be able to hold moisture for plant growth. Along the same lines, the media must also allow for drainage so the roots don’t starve or rot.

Choosing the right growing media for floriculture crops is very important. The media can affect the amount of nutrients that are available for the plants, the presence of water, and the ease of growth plants.

Plants need nutrients to grow. The nutrients needed by the plants can sometimes be present in the growing medium. Most often, with the use of artificial soil mixes and hydroponics, the nutrients must be added to the growing medium. The nutrients can sometimes be present in the growing medium but they are not available for the plants to take up into their roots because the pH level in the soil is not conducive to plant growth.

Nutrients might also leach, run out of the medium, causing the grower to continually add the nutrients. Without the presence of nutrients in the growing media, the plant may grow poorly, showing stunted growth, unhealthy coloring of the leaves, and may be more prone to disease and insect problems.

The ability of the growing media to drain water is very important for plant growth. Plant roots need oxygen to function properly and if the growing media is saturated with water, the plant roots will die due to lack of oxygen. The roots may also rot. Excess water in the growing media can also lead to insect problems.

In the production of floriculture crops, it is important to use a growing medium that is uniform. With a uniform mix, watering, fertilizing, and transplanting schedules can be developed in order to insure even growth of the crop. 11/15/05

What are the components of soil? Soil is the outer portion of the Earth’s crust that supports plant growth. Soil varies from one location to another based on the parent material that created the soil and the climate of that particular location. Soils are often characterized by the amount of mineral matter found in them.

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Mineral Matter Mineral matter is inorganic, non-living substances, that form soil. The three types of mineral matter found in soil are sand, silt, and clay. Sand is the largest soil particle. You can physically separate and see individual grains of sand. Sand is beneficial for soil drainage. However, if a soil is too sandy, it will not hold enough water for plant growth.

Mineral Matter Silt is a particle of soil that is produced by the action of water breaking down minerals. Silt is smaller than sand and is often found near rivers. Clay is the smallest particle of soil. Clay holds moisture very well but when it dries out, it often cracks and forms hard clumps.

Mineral matter Sand, silt, and clay, the 3 minerals found in soil, make up about 45% of soil composition. When there are equal amounts of sand, silt, and clay present in soil, it is called a loam.

Organic Matter Soils are also composed of 5% organic matter. Organic matter is living or dead plants and animals. Organic matter is necessary for plant growth because of its high nutrient content.

Pore spaces The remaining 50% of soil is composed of 25% air and 25% water. Soil is actually tiny particles with pore spaces around them. The pore spaces fill with air and water, and aid in plant growth.

Soil is: 25% air 25% water 45% mineral matter 5% organic matter

Soilless Mixes Soil is not used very often in the production of floriculture crops. Soil is very heavy, not always readily available, and can be full of undesirable weed seeds and insects. As a replacement to soil, greenhouse growers are turning to soilless mixes. A soilless mix is a combination of organic and inorganic substances that will provide sufficient support for plant growth.

A soilless mix does not contain topsoil. Common components in a soilless mix are: Peat moss - Peat moss is plant material that originates in bogs. Peat moss has great moisture and nutrient holding capacity. Peat moss is also lighter in weight compared to soil. It is important to remember that peat moss is acidic in nature and can affect the pH of the mix

Perlite - Perlite is white in color and comes from heat-treated lava rock. Perlite is used in the soil mix to aerate the soil. It is also very lightweight. Vermiculite- Vermiculite comes from the mineral mica and is shiny brown in color. It has high moisture holding capacity and is very lightweight. Vermiculite is often used as the media for germinating seeds.

The greenhouse grower can add other soil amendments to their mix like sand or bark. A soil amendment is an item added to a planting mix for the purpose of increasing the quality and growth of plants.

Greenhouse growers should compare the advantages and disadvantages of using a soilless mix versus a soil mix before deciding on the appropriate medium for their particular crop. 11/16/05

The advantages of a soilless mix are: The mix is uniform. It does not vary in components, texture, or nutrients. The mix is sterile. Sterilization is a process that eliminates all disease organisms, insects, or weed seeds. Soil mixes often contain these items and a grower who chooses to use a soil mix must pasteurize his or her soil before using it.

The advantages of a soilless mix are: Pasteurization is the process of heating soil to 180 degrees F for ½ hour to kill the harmful diseases, weed seeds, and insects.

Soilless mixes can be manipulated to improve the drainage and moisture holding capacity of the mix. A grower can personally mix the combination of components exactly to what he or she needs for their particular crop. Soilless mixes are easier to ship and move because they are lightweight.

The disadvantages of a soilless mix are: Fertilizers often need to be added more frequently to the mix because the mixes are lacking in minor plant food elements. Soil contains and holds many of these minor nutrients.

The disadvantages of a soilless mix are: When plants are grown outdoors, the wind can blow dry pots over because the mix is very light. It is sometimes difficult to transplant a plant from a soil mix to a soilless one. The roots often will not grow into the new media and the plant will die because it can not absorb any moisture.

Mineral Matter Non-living substances generally thought of as weather rock. Soil particles have 3 general sizes Sand – largest and increases drainage (feels gritty) Silt – medium size and gives a talc feel Clay – smallest and higher water holding capacity, feels slick.

Organic Matter Organic matter is living or dead plants and animals. Organic matter is necessary for plant growth because of its high nutrient content. Higher O.M. generally increases productivity.

What’s in a soilless mix? A soilless mix is a combination of organic and inorganic substances that provide sufficient support for plant growth. A soilless mix does not contain topsoil.

Common components in a soilless mix are: Peat moss is plant material that originates in bogs. Peat moss has great moisture and nutrient holding capacity. Perlite is white in color and comes from heat-treated lava rock. Perlite is used in the soil mix to aerate the soil.

Components Continued: Vermiculite comes from the mineral mica and is shiny brown in color. It has high moisture holding capacity and is very lightweight. Choir is fibers from coconut hulls which is hollow and aids in water and air holding while remaining lightweight.

Components Continued: Sand large soil particles used to reduce overall water holding capacity Amendments are add to change the air / water relationship of a mix while reducing the cost Wetting Agents are soaps used to aid water uptake of the dry mix. Also aids in rewetting.

The advantages of a soilless mix are: 1. The mix is uniform. It does not vary in components, texture, or nutrients. 2. The mix is sterile. Sterilization is a process that eliminates all disease organisms, in- sects, or weed seeds. Soil mixes often contain these items and a grower who chooses to use a soil mix must pasteurize his or her soil before using it. Pasteurization is the process of heating soil to kill harmful diseases, weed seeds, and insects.

The advantages of a soilless mix are: 3. Soilless mixes can be manipulated to improve the drainage and moisture holding capacity of the mix. 4. A grower can personally mix the combination of components exactly to what he or she needs for their particular crop. 5. Soilless mixes are easier to ship and move because they are lightweight.

The disadvantages of a soilless mix are: 1. Fertilizers often need to be added more frequently to the mix because the mixes are lacking in minor plant food elements. Soil contains and holds many of these minor nutrients. 2. When plants are grown outdoors, the wind can blow dry pots over because the mix is very light.

The disadvantages of a soilless mix are: 3. It is sometimes difficult to transplant a plant from a soil mix to a soilless one. The roots often will not grow into the new media and the plant will die because it can not absorb any moisture. 4. There is a cost to the media

REVIEW

What are the ingredients of soil? Air Water O.M. Mineral Matter

What are the sizes of soil particles? Sand Silt Clay

What are the materials used for soilless mixes? Peat Perlite Vermiculite Choir Amendments – bark, rice hulls, … Sand Wetting Agents

What are the advantages of mixes? Uniform Sterile Light Amendable

What are the disadvantages of mixes? Light Need nutrients Cost Transplant issues