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Soils and Plant NutritionHort 101: 

Soils and Plant Nutrition Hort 101

What is Soil?: 

Soil is the medium in which plants grow - the basis for plant growth. What is Soil?

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Mineral 45-48% Air 20-30% Water 20-30% Organic Matter 2-5% Sand Silt Clay Four Major Components of Soil

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Soil Components Mineral Sand = 2.0 to 0.05mm Silt = 0.05 to 0.002mm Clay = less than 0.002mm

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The proportion of sand, silt and clay determine a soil’s texture.

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Improves the soil’s physical condition. Supplies plant nutrients. Increases water infiltration. Helps decrease erosion. Improves soil tilth (the soil’s ability to resist compaction). ••• Basically nature’s way of recycling! Five Things Organic Matter Does for Soil:

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The smallest particles of soil are called colloids. Colloids have a negative charge so they attract positively charged particles. Colloids repel other negatively charged particles - like a magnet. An element or group of elements with an electrical charge is called an ion. Ions with negative charges are called anions. Ions with positive charges are called cations.

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Plant Nutrients C HOPKN’S CaFe Mg B Mn Cu Zn Mo Cl See Hopkin’s Cafe Managed By My Cousin Mo Clay

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Carbon - Hydrogen - Oxygen The three most abundant elements - plants obtain them from water and air. These three elements make up more than 94% of plant dry tissue. The remaining 13 elements make up less than 6% of plant dry tissue.

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Nitrogen Phosphorus Potassium Sulfur Calcium Magnesium Manganese Iron Boron Zinc Copper Molybdenum Chlorine Macronutrients Micronutrients

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A nitrogen deficiency most limits plant growth. Provides a visual green response in plants. Plants use large amounts of nitrogen. Necessary for the production and transfer of energy - photosynthesis. Stimulates plant growth. Increases seed and fruit yield. Improves the quality of leaf and forage crops. Present in the soil in three forms. Nitrogen . . . (N)

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Nitrogen is present in the soil in three major forms: Organic Inorganic Elemental

Nitrogen Deficiency: 

Nitrogen Deficiency

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Phosphorus . . . (P) Also an essential part of photosynthesis. Responsible for utilization of starch and sugar. Cell nucleus formation. Cell division and multiplication. Cell organization. Transfer of heredity.

Phosphorus Deficiency: 

Phosphorus Deficiency

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Potassium . . . (K) After nitrogen, plants use the largest amount of potassium. Plays an essential role in the metabolic process of plants. Plays a role in raising the disease resistance of many plant species.

Potassium Deficiency: 

Potassium Deficiency

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Calcium . . . (Ca) An essential part of the wall structure and strength of plant cells. Provides for normal transport and retention of other elements. Does not move in plant, deficiency develops in new leaves Counteracts the effects of alkali salts and organic acids within the plant.

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Magnesium . . . (Mg) Is essential for photosynthesis. Makes up a part of the chlorophyll in green plants. Helps activate plant enzymes needed for plant growth. Dolomitic lime and epsom salts contain Magnesium

Magnesium Deficiency: 

Magnesium Deficiency

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Sulfur . . . (S) Activates plant enzymes. Is required for nodulation and nitrogen fixation of legumes. Present in glycosides which give the characteristic odors and flavors of mustard, onion and garlic.

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Manganese . . . (Mn) Activates plant enzymes. May substitute for magnesium Iron . . . (Fe) Essential for the synthesis of chlorophyll. Symptoms include chlorosis between the veins with green veins

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Copper . . . (Cu) Essential for plant growth. Activates many plant enzymes. Zinc . . . (Zn) Regulates plant growth by controlling the synthesis of indoleacetic acid. Activates plant enzymes.

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Boron . . . (B) Regulates the metabolism of carbohydrates in plants. Molybdenum . . . (Mo) Required in tiny amounts.

Nutrient Deficiencies: 

Nutrient Deficiencies A note about nutrient deficiencies: While many deficiencies show specific symptoms this is an inexact science at best. Many of the symptoms overlap so the only way to be sure is with a combination of tissue analysis and soil sampling.

Quiz Time: 

Quiz Time So just exactly who is Mo?

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Soil pH is a measure of the hydrogen ion concentration in the soil. Buffer pH is the soil’s ability to resist changes in pH.

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Optimum pH for most plants 5.5 to 6.5 pH Units

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Liming Materials Calcitic Lime Dolomitic Lime Hydrated Lime (Use 75% of the above recommended amount) Wood Ashes (Use with caution!)

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Fertilizer ratio describes the relative proportions of N-P-K in a fertilizer. Fertilizer grade (or analysis) refers to how much of an element there is in a fertilizer based on percentage by weight.

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Complete when it contains all three major plant nutrients. Incomplete when it lacks one of the major plant nutrients. Balanced when it contains equal amounts of N-P-K. Premium refers to fertilizers that contain the minor elements Slow release refers to fertilizers that release the elements slowly over time Fertilizer is referred to as:

Let’s Do Some MATH: 

Let’s Do Some MATH Many fertilizer recommendation come as pounds of (insert element) per 1000 square feet. If you add that much product you will NOT get the right amount because the product contains only a percentage of the element. So now what do you do?

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To determine the amount of ammonium sulfate a 5,000-sq ft lawn needs if the lawn requires one lb of nitrogen per 1,000 sq ft... Lawn: 5,000 sq. ft. Fertilizer: Ammonium sulfate (21-0-0) Rate of Application: 1lb of nitrogen per 1,000 sq. ft. Ammonium sulfate is 21% nitrogen. 21% is the same as 0.21 or 21/100. This means for every 100 lb. of fertilizer there are 21 lb. of nitrogen. We need 1 lb of nitrogen for every 1,000 sq. ft. Using proportions, we can calculate the amount of ammonium sulfate needed to get 1 lb of N. “X” represents the unknown amount being calculated.

Tim’s Method: 

Tim’s Method ½ lb/1000 ft2 = 50 1 lb/1000 ft2 = 100 1.5 lb/1000 ft2 = 150 2 lb/1000 ft2 = 200 2.5 lb/1000 ft2 = 250 See the pattern? To get the right amount of product take the constant supplied on the right and divide by the analysis of the element you want. For the example to apply 1 lb of nitrogen /1000 ft2 using 21-0-0. 100/21 = 4.76 lbs of 21-0-0 per 1000 ft2.

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How much lime and fertilizer should I add to my garden?

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Soil testing is essential to applying the correct fertilizer and Lime! Adding fertilizer to the soil without testing is like baking a cake without reading the recipe or measuring the ingredients

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A good sample is critical to getting a good soil analysis!

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Need to add video here of collecting a soil sample

Let’s Review: 

Let’s Review To a horticulturist what is soil? What is organic matter and what does it do for the soil? What is pH? What is buffer pH? How can I KNOW how much lime and fertilizer to add?

Other Recommended InformationFollow the Links: 

Other Recommended Information Follow the Links Home and Garden Information Center (HGIC) Soil testing Changing the pH of your soil Fertilizers Composting Bob Lippert’s Soil Page Indoor plants Fertilizing Lawns Mulch Fertilizing Trees Fertilizing Vegetables

Credits: 

Credits I am not a soil scientist so much of this was taken from several sources. Some of the following are sources I’ve “stolen” this information from. Thanks to all who had a part. South Carolina Master Gardener Manual Home and Garden Information Center (http://hgic.clemson.edu) Bob Lippert’s Powerpoint (Clemson University) Slide Presentation Michelle Clark’s (Richland County Master Gardener) MG Slide Presentation Brian Smith’s (Charleston County Extension Agent) COTS Slide Presentation

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This concludes the soil module for Horticulture 101, but don’t stop here. If you have questions feel free to email me at tdvs@clemson.edu Return to Hort 101 site