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Managing Soil to Keep It Productive Developed by: Hudson Minshew Oregon State University Extension Service Susan Donaldson University of Nevada Cooperative Extension NRCS, Bozeman, Mont.
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Part One: Fertilizing What do my soil test results mean? What nutrients do plants need? How can I supply those nutrients?
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What kind of information does my soil test report provide? Particle size analysis Soil organic matter content pH Soluble salts Nutrient content USDA NRCS
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Particle size analysis Provides the relative percentages of sand, silt, and clay Allows determination of soil textural class A loamy texture is generally best for most plants NRCS, Bozeman, Mont.
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Soil organic matter (OM) Living or dead plant and animal residue Measured in % OM content is highly variable Generally, 3 to 8 % OM content is good for plants UNCE, Reno, Nev.
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pH Indicates relative acidity or alkalinity pH 7 = neutral; less than pH 7 = acid; more than pH 7 = alkaline or basic Adapted from library.thinkquest.org by A. Miller
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Soil pH and nutrients Adapted from www.soil.ncsu.edu by A. Miller Widest part of the bar indicates maximum availability
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What makes soils acid? Acid soils: pH is below 7 Soils become acid due to heavy rainfall that weathers soils quickly Basic cations such as calcium, magnesium, and potassium are leached from the soil profile This natural weathering process makes soils acid
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Raising the pH of acid soils Add lime to raise the pH (making soil less acid) Lime most often consists of calcium carbonate Plant response will be relatively slow, taking weeks or months
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What makes soils alkaline? Alkaline soils: pH is above 7 Soils that have not been greatly weathered or leached Soils high in calcium Reduces solubility of all micronutrients Adapted from library.thinkquest.org by A. Miller
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http://ag.arizona.edu Example of crop grown in alkaline soil
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Adapted from ag.arizona.edu by A. Miller
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Soluble salts A measure of inorganic chemicals that are more soluble than gypsum, such as sodium, calcium, magnesium, chloride, sulfate and bicarbonate Salty soils are a problem in arid regions or in poorly drained soils USDA NRCS
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Classifying salt-affected soils Electrical conductivity measurements (EC) Exchangeable sodium percentage (ESP) Salt-affected soils are commonly classified for management purposes into three groups: saline, sodic, and saline-sodic based on EC and ESP
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Managing salt-affected soils Select plants that can tolerate salinity Avoid excess or salty forms of fertilizers Incorporate organic matter If appropriate, add sulfur to lower the pH
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Managing salt-affected soils In soils with good drainage, periodically leach the salts below root zone with high quality irrigation water (avoid if high water table present) Check with your local Extension office for help
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Plant nutrients Substances necessary for plant growth Some, such as hydrogen, oxygen and carbon, come from the air and water Others, such as nitrogen and phosphorus, may need to be added Excess or improper use of fertilizers may result in water pollution
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Macronutrients N = nitrogen P = phosphorus K = potassium
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More macronutrients H = hydrogen O = oxygen C = carbon Ca = calcium Mg = magnesium S = sulfur
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Micronutrients Fe = iron Mn = manganese Zn = zinc B = boron Mb = molybdenum Ni = nickel Cu = copper Co = cobalt Cl = chlorine
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Six questions to ask yourself before you add fertilizer 1.Which elements do I need? (N, P, K, S, Ca) 2.How much do I apply? 3.What type of material do I use? 4.Which application method is best? 5.When is the best time to apply it? 6.Will I get a return on my investment?
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Types of fertilizers Chemical fertilizers Organic fertilizers (bone meal, compost, manure, etc.) www.farmphoto.com
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What’s in the bag? WAY TO GROW FERTILIZER 28 – 14 - 5 GUARANTEED ANALYSIS Total nitrogen 28% 6% Ammonium nitrogen 14% Urea nitrogen Available phosphoric acid 14% Soluble potash 5% Derived from sulfur-coated urea, etc. Product name NPK formula Nitrogen content Phosphorus content Potassium content Specific sources
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How much fertilizer do I need to apply? Estimate the amount of fertilizer needed based on soil test results, crop needs and area to receive fertilizer Most fertilizer recommendations are in pounds per 1,000 square feet, or pounds per acre
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Calculating fertilizer rates X 100 Pounds of nutrient recommended Percentage of nutrient in fertilizer material To convert a recommendation to pounds/acre of an actual fertilizer material, use the following formula :
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Calculating land area Length x Width = Area If the area is oddly shaped or oval, calculate using a regular shape that closely fits the shape of the land to be fertilized 100 ft 200 ft 150 ft
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Fertilizing with manures Good source of nutrients and organic matter Protects soil from raindrop impact and erosion Local supply often available at no cost OSU Extension Service
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Poultry manure is high in nitrogen Beef and horse manure tends to be lower in nitrogen Sheep manure is high in potassium Different sources of manure have different amounts of nutrients UNCE, Reno, Nev.
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Cautions for fertilizing with manures Watch out for weeds and pathogens Know the manure nutrient content Consider the salt content Univ. of Oregon
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Cautions for fertilizing with manures Incorporate or apply evenly to avoid smothering plants Don’t apply on frozen slopes Avoid leaching nutrients into waterways UNCE, Reno, Nev.
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USDA NRCS Nutrient deficiencies
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Visual symptoms of deficiencies: Nitrogen http://agri.atu.edu
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Visual symptoms of deficiencies: Phosphorus http://agri.atu.edu
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Visual symptoms of deficiencies: Potassium Alfalfa Corn http://agri.atu.edu http://ipm.iastate.edu
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Visual symptoms of deficiencies: Calcium http://agri.atu.edu
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Visual symptoms of deficiencies: Zinc http://agri.atu.edu
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Visual symptoms of deficiencies: Manganese http://agri.atu.edu
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What we’ve learned Use soil test results to guide you in amending your soil Test results are only as good as the sample you collect Fertilize to meet plant needs, and avoid costly overuse that may pollute water
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Part II: Soil Surveys How to use a soil survey How to find a map unit Map unit descriptions Soil ratings and capabilities
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USDA NRCS Where do soil surveys come from, and where can I get one?
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http://websoilsurvey.nrcs.usda.gov
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Why should we use soil surveys? Contain practical information for the landowner Can prevent management mistake Help determine the potential of your land
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How do I use a soil survey? Locate your property on the “Index to Map Sheets” page Note the number of the map sheet Find that sheet Locate your property on the map sheet Make a list of map unit symbols
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Soil map units A map unit describes a soil “type” in the soil survey “Map-unit descriptions” are found at the beginning of the survey Soil map units are arranged alphabetically as well as numerically in the soil survey
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Soil map unit example 630 Fleischmann gravelly clay loam Soil textural class is part of map unit name Number designation Name given by soil scientists conducting survey
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What can you do with the number? Determine capabilities and limitations See “Summary of Tables” in the soil survey for additional data on a specific soil use For our example soil, can we build a septic absorption field? See Table 10: Lists a severe limitation due to cemented pan
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NRCS Web-based soil surveys http://websoilsurvey.nrcs.usda.gov/app Can search by address, or use the map to zoom in Steps in using the site: –Select area of interest (your property) –View the soil map and learn about the soil properties –Use soil data explorer for additional information –Create a custom soil report
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What does all the information mean? USDA NRCS
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Soil limitations NRCS, Bozeman, Mont.
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Suitability ratings Temperature and precipitation data Freeze dates and growing season Productivity Building site development Other information
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Suitability for irrigation Physical and chemical properties (percent OM, pH, permeability, available water capacity) Soil surveys can differ in the information they provide.
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Restrictive features Cemented pan Droughty Erodes easily Flooding Low strength Restrictive layer Shrink-swell potential UNCE, Reno, Nev.
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Capability classes Classes I and II—good farmland with few to moderate limitations Classes III and IV—severe to very severe limitations for growing crops Classes V and VI—limitations that are impractical to remove. Classes VII and VIII—very severe, unsuited for cultivation.
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Capability classes USDA NRCS
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Land capability and yields USDA NRCS
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To wrap it up... Soil surveys are generated by NRCS scientists They are available in printed form or on the Web Soil surveys are useful for determining capabilities and limitations of your soils
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Additional activity: Use the Web soil survey
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Enter an address
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Select “Area of Interest”
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Go to “Soil Map”
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Clip “Area of Interest” to property level
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Go to “Soil Data Explorer”
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Click on “Vegetative Productivity”
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Look at “Yields of Irrigated Crops”
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Click on “Sanitary Facilities”
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Look at “Septic Tank Absorption Fields”
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Generate your custom soil resource report As you use “Soil Data Explorer” to look at different features, click “Add to Shopping Cart” to add the information to the report Click on the “Shopping Cart” button to get the report
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