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Transcript
Abiotic Disorders: Soil and Fertilizer Components Janet Hartin UCCE Environmental Horticulturist San Bernardino, Los Angeles, and Riverside Counties Major Components • Mineral matter • Organic matter • Air • Water Physical Properties of Soil • Soil texture • Soil structure • Soil color • Bulk density USDA Textural Triangle Soil Textures Examples of Soil Structure Granular Blocky (Subangular) (Angular) Prismatic Columnar Platy Wedge Compaction Can Destroy Soil Where Does Compost Fit In? What is composting? Grass clippings Food scraps Leaves Using the natural process of decay to change organic wastes into a valuable humus-like material called compost Compost Compost Promotes Soil Health • Supplies organic matter to soil • Attracts earthworms • Stimulates beneficial soil microorganisms • Increases soil and nutrient water holding capacity in sandy soils/drainage in heavy soils Compost Supplies Some Plant Nutrients Compost is not a fertilizer, but does contain plant nutrients • Nitrogen and phosphorus are mostly in organic forms – Released slowly to plants – Not readily leached from the topsoil • Compost contains small amounts of nutrients that are essential for plant growth When is Compost Ready? Compost is mature when • It is dark brown • It is crumbly, loose, and humus-like • It has an earthy smell • It contains no readily recognizable feedstock • The pile has shrunk to about 1/3 of its original volume Simple Tests to Ensure Compost Readiness Bag test: Compost left in a plastic bag should remain fresh-smelling after two days! Germination test: Make sure that seeds actually germinate in it! Using Finished Compost • Soil amendment – This is the main use of compost. – Mix evenly into soil at least 6 inches deep for annuals and 12 inches for shrubs. Add at least 30% by volume. – Do not add compost to tree planting sites! Avoid Root-Bound Trees! Fertilizers and Plant Nutrition Essential Plant Nutrients • Macronutrients – Required in relatively large amounts. • Micronutrients – Required in small amounts. – Minor or trace elements. Macronutrients • Fall into one of three categories: – Non-Mineral Elements – Primary Nutrients – Secondary Nutrients Non-Mineral Elements • (C) Carbon • (H) Hydrogen • (O) Oxygen Primary Nutrients • (N) Nitrogen • (P) Phosphorus • (K) Potassium Secondary Nutrients • (Ca) Calcium • (Mg) Magnesium • (S) Sulfur Micronutrients • • • • (Fe) Iron (Cu) Copper (Zn) Zinc (B) Boron • (Mo) Molybdenum • (Mn) Manganese • (Cl) Chlorine Function & Deficiency Symptoms of Nutrients Nitrogen • Function – Promotes growth of leaves and stems. – Gives dark green color and improves quality of foliage. – Necessary to develop cell proteins and chlorophyll. Nitrogen • Deficiency Symptoms – Sick, yellow-green color. – Short stems, small leaves, pale colored leaves and flowers. – Slow and dwarfed plant growth. Phosphorus • Functions – Stimulates early formation & growth of plants. – Provides for fast & vigorous growth and speeds maturity. – Stimulates flowering & seed development. – Necessary for the enzyme action of many plant processes. Phosphorus • Deficiency Symptoms – Decrease in growth. – Slow maturity. – Older leaves are purplish color. Potassium • Functions – Used to form carbohydrates & proteins. – Formation and transfer of starches, sugars, & oils. – Increases disease resistance, vigor, & hardiness. Potassium • Deficiency Symptoms – Mottled, spotted, streaked or curled leaves. – Scorches, burned, dead leaf tips & margins. Potassium • Deficiency Symptoms – Mottled, spotted, streaked or curled leaves. – Scorches, burned, dead leaf tips & margins. Calcium • Functions – Improves plant vigor. – Influences intake & synthesis of other plant nutrients. – Important part of cell walls. Calcium • Functions – Improves plant vigor. – Influences intake & synthesis of other plant nutrients. – Important part of cell walls. Magnesium • Functions – Influence the intake of other essential nutrients. – Helps make fats. – Assists in translocation of phosphorus & fats. Magnesium • Deficiency Symptoms – Interveinal chlorosis. • (Yellowing of leaves between green veins) – Leaf tips curl or cup upward. – Slender, weak stems. Sulfur • Functions – Promotes root growth and vigorous vegetative growth. – Essential to protein formation. Sulfur • Deficiency Symptoms – Young leaves are light green with lighter color veins. – Yellow leaves and stunted growth. Iron • Functions – Essential for chlorophyll production. – Helps carry electrons to mix oxygen with other elements. Iron • Deficiency Symptoms – Mottled & interveinal chlorosis in young leaves. – Stunted growth & slender, short leaves. Copper • Functions – Helps in the use of iron. – Helps respiration. Copper • Deficiency Symptoms – Young leaves are small and permanently wilt. – Multiple buds at stem tips. Zinc • Functions – Plant metabolism. – Helps form growth hormones. – Reproduction. Zinc • Deficiency Symptoms – Retarded growth between nodes (rosetted) – New leaves are thick & small. – Spotted between veins, discolored veins. Boron • Functions – Affects water absorption by roots. – Translocation of sugars. Boron • Deficiency Symptoms – Short, thick stems tips. – Young leaves of terminal buds are light green at base. – Leaves become twisted & die. Boron • Deficiency Symptoms – Short, thick stems tips. – Young leaves of terminal buds are light green at base. – Leaves become twisted & die. Manganese • Functions – Plant metabolism. – Nitrogen transformation. Manganese • Deficiency Symptoms – Interveinal chlorosis. – Young leaves die. Complete vs. Incomplete Fertilizers • Complete Fertilizers – Contain all 3 primary nutrients (nitrogen, phosphorus, & potassium) • Examples: – 10-10-10 – 15-30-15 – 20-5-20 Complete vs. Incomplete Fertilizers • Incomplete Fertilizers – DO NOT have all 3 primary nutrients. • Examples: – 20-0-0 – 0-20-0 – 12-0-44 Organic vs. Inorganic Fertilizers • Organic Fertilizers – Come from plant or animal matter & contain carbon compounds. • Examples: – Urea – Sludge – Animal Tankage Organic vs. Inorganic Fertilizers • Advantages of Organic Fertilizers – Slow release of nutrients. – Not easily leached from soil (less potential to result in water pollution). – Add organic components to soil. Organic vs. Inorganic Fertilizers • Disadvantages of Organic Fertilizers – Expensive – Low nutrient content – Take longer to show effects N-P-K Content of Some Organic Products ■ Alfalfa Meal Average NPK analysis: 2-1-2 ■ Blood Meal Average NPK analysis: 12-0-0 ■ Bone Meal Average NPK analysis: Varies from about 1-11-0 to about 3-15-0, also contains about 24 percent calcium. ■ Coffee Grounds Average NPK analysis: 2-0.3-0.6 ■ Compost Average NPK analysis: 0.5-0.5-0.5 to 4-4-4; about (25 percent organic matter). ■ Cottonseed Meal Average NPK analysis: 6-0.4-1.5 ■ Eggshells (adds calcium mostly) Average NPK analysis: About 1.2-0.4-0.1 ■ Epsom Salts Average analysis: 10 percent magnesium, 13 percent sulfur. ■ Feather Meal Average analysis: Nitrogen 7 to 12 percent. ■ Fish Emulsion Average NPK analysis: 5-2-2, also contains sulfur. ■ Mushroom Compost Average NPK analysis: About 2-1-1 ■ Soybean Meal Average NPK analysis: 7-2-1 ■ Worm Castings Average NPK analysis: 0.5-0.5-0.3 Choosing a Fertilizer General Rules • Method used should be…. – Practical – Effective – Cost Efficient • Method used affects nutrient availability for plant use. • Fertilizer must be dissolved and reach plant roots. Banding • Placing a band of fertilizer about 2 inches to the sides & about 2 inches below seed depth. • Do NOT place below seeds because fertilizer will burn roots. Sidedressing • Placing a band of fertilizer near the soil surface and to the sides after seedlings emerge from the soil. Topdressing • Mixing fertilizer uniformly into the top one to two inches of growing media around the plant. Perforating • Placing fertilizer in 12 – 18” holes drilled 18 – 24” around the canopy drip line of fruit trees. • Cover the holes & the fertilizer slowly dissolves. Broadcasting • Spreading fertilizer to cover the entire production area. How much Fertilizer do Landscape and Edible Plants Need? Most vegetables: - 0.5 to 2 lbs of nitrogen per 100 feet of row. Ammonium phosphate (16-20-0) is a good choice if compost hasn’t been worked into the soil When seedlings are 3-4” reapply Before planting fruit trees place one of the following in the bottom of the planting hole and cover with 1-2 inches of soil: •1 lb treble super phosphate (0-45-0) •2 lb single super phosphate (0-25-0) •2 pounds fine phosphate rock* •3 ½ pounds bone meal* •7 to 8 pounds well composted/aged manure* * Blend with backfill to avoid burning the roots. Plant the tree. Then, spread an equal amount of one of the above on the soil surface around the tree. Nitrogen Application – Fruit Trees Amount of nitrogen to Apply Per Tree Per Year Season Orange Juice Can Lbs. of Lbs. of Ammonium Actual N Sulfate 1st (after planting) ½ can (twice) 0.5 0.1 2nd 1 can (twice) 1.0 0.2 3rd 3 cans 1.5 0.3 4th 5 cans 2.5 0.5 5th 7 cans 3.5 0.7 6th 8 to 10 cans 4.5 0.8 to 1.0 Landscape Tree Fertilization - Not more than .5 lb N per inch trunk circumference - OK to wait until minor symptoms develop Lawn Fertilization Total: 4-5 lbs N/year - 2-3 lbs N as ammonium sulfate - 2-3 lbs N as a 3-1-2 ratio fertilizer Lawns: 3-1-2 NPK Ratio twice a Year Why Have Garden Soil Tested? Most Important Reasons: - To determine pH (too high can tie up micronutrients) - To determine salt content (plant injury) Other Reasons: - To determine texture (sand, silt, clay) and water holding capacity (although you can do this easily yourself using a jar of water) - To determine nutrient content (too much or too little) There is no Need to Test Levels of Nitrogen Since it is so Mobile! - Results will be invalid by the time you receive the results - Apply nitrogen based on MG Handbook recommendations for various types of plants How to Conduct a Soil Test - Identify homogeneous areas of your yard - Collect between 6-10 soil samples within each area and mix them together thoroughly - Sample depth should be between 6” and 1’ depending on type of plant and root zone - Submit about 1 pint (2 cups) to a reputable soil testing lab Tips - Avoid fertilizing or adding soil amendments just prior to testing - Make sure compost and other organic soil amendments are broken down and stable before their addition - Consider water quality as well. It may need to be tested Tips (con’d) Most nutrient-related problems can be controlled simply by reducing pH and EC levels. - High pH (above 7.5) can tie up nutrients such as zinc, iron, and manganese. - Add elemental sulfur or fertilizer with nitrogen sulfate to reduce a high pH - Add organic matter to your soil or garden in raised beds amended with organic matter and/or peat Refer to Table Below for Rates Pounds of Sulfur Needed to Lower Soil pH Material pH Change Pounds per 100 Square Feet* Sulfur 7.5 to 6.5 8.0 to 6.5 8.5 to 6.5 1.5 3.5 4.0 Iron sulfate 7.5 to 6.5 8.0 to 6.5 8.5 to 6.5 12.5 29.0 33.2 * Higher rates are required on fine-textured clayey soils and soils with a pH of 7.3 and above Electrical Conductivity - Measures how easily an electrical current can pass through the soil - High EC value indicates high salt levels - Many plants are sensitive to salt contents as low as 3-4 dS/m. Most are sensitive to ECs above 8 dS/m - Salts include cations and anions that are essential plant nutrients (such as potassium and nitrate) as well non-essential elements such as sodium High Levels of Sodium A Few Very Salt-Sensitive Plants - Crape myrtle Plum Apple Pear Desert Willow A Few Salt-Tolerant Plants - Honey locust Honey Mesquite Chilean mesquite Salt Cedar Salt grass This Website Lists Salt Tolerances of Several Plants http://ucanr.org/sites/sjcoeh/files/98902.pdf How Can you Reduce Levels of Harmful Salts? - Leach below the root system (apply water slowly for several hours) - If high EC is due to sodium, apply gypsum to displace sodium with calcium (you still need to leach the sodium out though!) The Michigan State University Soil Test Website Allows You to Type in Test Results (pH, nutrient levels, CEC, etc. for Specific Recommendations in Landscapes and Gardens Msusoiltest.com Thank You! Janet Hartin [email protected] (951)313-2023