Growing Plants Hydroponically vs. In Soil:

The Soil Profile

Questions

•Why do we need to know what is in the soil?

• How do we determine what is in the soil?

Particle Sizes

Soil StructureSoil structure is how the soil particles fit together

Massive

Granular soil structure is the best. Plants have good root development. Water movement is at an appropriate rate – doesn’t stay to wet or too dry.

Silty soils have a granular soil structure.

Sandy soils typically have a loose soil structure.

Clayey soils have a blocky or platy structure

Soil Texture

Sand has the largest particles. Sandy soils have low moisture and nutrient holding capacity.

Silt has medium sized particles. Silt has a good moisture and nutrient holding capacity.

Clay has the smallest sized particles. Clayey soils have high water and nutrient holding capacity.

Loam has almost equal parts of sand, silt and clay. This is the ideal texture for most non container outside plants.

Soil texture

Soil Texture Triangle Examples

1. 20% Clay, 10% Sand and 70% Silt?2. 30% Clay, 60% Sand, and 10% Silt?3. 55% Clay, 45% Sand?

Dirt Shake

• Horizon O is the organic matter

• Horizon A is the topsoil

• Horizon B less topsoil and less organic matter

• Horizon C Parent material

• Bedrock below Horizon C

Soil ProfileHorizon O – Organic matter. This layer us usually less than an inch thick. Litter decomposes into nutrients that enrich the soil. In area where the

temperature is lower, the composition of organic matter is slower.Horizon A – top layer of soil. Nutrients, bacteria, fungi, and small animals

are abundant. Plant thrive because of the nutrients in it.

Horizon B –Light in color because it has less top soil and organic matter

Horizon C – Called the parent material because it is the weathered roc and

partly weathered soil from which the soil layers above are formed. Bedrock – solid rock. Parent material is formed from the bedrock after a long

weathering process. Happens either physical or chemical. Physical – wind or water erosion, glacial activity, freezing and thawing

and biotic activity (plant roots, animals, micro-organisms)Chemical – leaching, oxidation, carbonation, and hydration

Identifying Texture by Feel• Feel test – Rub some moist soil between your fingers.

• Sand feels gritty.• Silt feels smooth.• Clays feel sticky.

• Ball squeeze test – Squeeze a moistened ball of soil in your hand.• Coarse textures (sand or sandy loam) soils break with slight pressure.• Sandy loams and silt loams stay together but change shape easily.• Fine textured (clayey or clayey loam) soils resist breaking.

• Ribbon test – Squeeze a moistened ball of soil out between your thumb and fingers.• Sandy soils won’t ribbon.• Loam, silt, silty clay loam or clay loam soil ribbons less than 1 inch.• Sandy clay loam, silty clay loam or clay loam ribbons 1 to 2 inches.• Sandy clay, silty clay, or clay soil ribbons more than 2 inches.A soil with as little as 20 percent clay may behave as a heavy clayey soil. A soil needs 45 percent to over 60 percent sand to behave as a sandy soil.

Soil Profile Review

pH• Soil pH is a measure of the acidity or alkalinity of

soils. • Soil pH ranges from 0-14. 0-6.9 (low pH) is

considered an acid soil, 7 indicates a neutral soil and 8-14 (high pH) is considered an alkaline soil.

• Lime will raise the pH value in soils (make the soil less acidic).

• Calcium or sulfur will lower the pH value in soils (make the soil more acidic).

• The ideal pH value for vegetable garden soils are 5.5 to 7.0.

• Permeability is the rate at which water moves through the soil.

• Water holding capacity is the ability of a soil to hold water for plant use.

• Porosity is the amount of air space between soil particles.

• 50% of soil should be pore space which includes 25% water space and 25% air space.

• 50% of soil should be soil particles which include 45% mineral matter and 5% organic matter.

What is Soil Made up of?

http://www.physicalgeography.net/fundamentals/images/soil_breakdown.gif

Soil Sampling 1. Soil sampling and testing is essential for an accurate fertilizer

recommendation for growing plants. 2. Soil sampling procedures.

a. Create a visual grid of the area to be planted. For gardens and landscapes, take 5-10 subsamples from the site to be evaluated. Sample before the growing season.

b. Use a stainless steel soil-sampling probe.

c. Take the surface sample to tillage depth or about 3-4 inches for lawns and 6-8 inches for crops.

Soil sampling cont.

• d. Mix the soil samples together. e. Remove any grass, rocks or other material besides

soil. f. Avoid unusual spots in the lawn or field. Those areas need to be sent in a separate box. g. Place soil samples in a box, which you can obtain

from the County Extension Office along with Soil Sample Information sheet, send the box and information to Agronomic Division Soil Test Lab in Raleigh for a free soil test

Soil Color-Munsell Color Chart

Group Rotation

• You will have 10 minutes at each one of the stations.

• Follow the directions on the sheet or wait for me to come around and give you directions.

• Make sure to complete any work that is in your workbook on pages 6-7.