Managing Soil to Keep It Productive

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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, MT
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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, MT
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Soil organic matter (OM)

• Living or dead plant and animal residue
• Measured in percent
• OM content is highly variable
• Generally, 3 to 8 OM content is good for plants

UNCE, Reno, NV
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pH

• Indicates relative acidity or alkalinity
• pH 7 neutral less than 7 acid more than 7
  alkaline or basic

Adapted from library.thinkquest.org
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Soil pH and nutrients
Adapted from www.soil.ncsu.edu
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 because of 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
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Example of crop in alkaline soil
ag.arizona.edu
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Adapted from ag.arizona.edu
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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 Cooperative 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

• Which elements do I need? (N, P, K, S,
  Ca)
• How much do I apply?
• What type of material do I use?
• Which application method is best?
• When is the best time to apply it?
• 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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Whats in the bag?
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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
  1000 square feet, or pounds per acre

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Calculating fertilizer rates
To convert a recommendation to pounds/acre of an
actual fertilizer material, use the following
formula
X 100
Pounds of nutrient recommended Percentage
of nutrient in fertilizer material
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Calculating land area

• Length Width Area
• If area is odd shaped or oval, calculate using a
  regular shape that closely fits the shape of the
  land to be fertilized

200 ft
150 ft
150 ft
100 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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Different sources of manure have different
amounts of nutrients

• Poultry manure is high in nitrogen
• Beef and horse manure tends to be lower in
  nitrogen
• Sheep manure is high in potassium (K)

UNCE, Reno, NV
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Cautions for fertilizing with manures

• Watch out for weeds and pathogens
• Know the manure nutrient content
• Consider the salt content

N- P- K
OSU Extension Service
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Cautions for fertilizing with manures

• Incorporate or apply evenly to avoid smothering
  plants
• Dont apply on frozen slopes
• Avoid leaching nutrients into waterways

UNCE, Reno, NV
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Visual symptoms of deficiencies Nitrogen
agri.atu.edu
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Visual symptoms of deficiencies Phosphorus
agri.atu.edu
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Visual symptoms of deficiencies Potassium
Corn
Alfalfa
agri.atu.edu
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Visual symptoms of deficiencies Calcium
agri.atu.edu
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Visual symptoms of deficiencies Zinc
agri.atu.edu
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Visual symptoms of deficiencies Manganese
agri.atu.edu
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What weve 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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Where do soil surveys come from, and where can I
get one?
USDA NRCS
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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

Name given by soil scientists conducting survey
Number designation
Soil textural class is part of map unit name
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What do 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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Soil limitations
NRCS, Bozeman, MT
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Other information

• Suitability ratings
• Temperature and precipitation
• Freeze dates and growing season
• Productivity
• Building site development

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Other information

• Suitability for irrigation
• Physical and chemical properties (OM, pH,
  permeability, AWC)
• Soil surveys can differ in what information they
  provide.

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Restrictive features

• Cemented pan
• Droughty
• Erodes easily
• Flooding
• Low strength
• Restrictive layer
• Shrink-swell potential

UNCE, Reno, NV
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Capability classes

• Class I II --good farmland with few to
  moderate limitations
• Class III IVsevere to very severe limitations
  for growing crops
• Classes V VIlimitations that are impractical
  to remove.
• Classes VII VIIIvery 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...

• Where do soil surveys come from?
• Where can I get my soil survey?
• What information can I get from a soil survey?