Soil Fertility and Pasture Fertilization

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Soil Fertility and Pasture Fertilization

• Les Vough
• Forage Crops Extension
• Specialist Emeritus

INAG 116
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Causes of low pasture productivity

• ? Lack of adequate fertilization.
• ? Poor grazing management.
• ? Unproductive species.

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Adequate Fertilization

• ? Soil test every 2-3 years.
• ? Lime and fertilize according to soil test
  recommendations.

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Soil Testing

• ? If no-till seeding, sample from 2 depths --
  surface to 2 inches and surface to 8 inches or
  normal plow layer if pasture has ever been
  plowed.
• ? If tilled soil seeding, sample from surface to
  8 inches or the plow or tillage depth.

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Correct Fertility Deficiencies

• ? Do not attempt seeding unless willing to apply
  the recommended amounts of lime and fertilizer.
• ? pH affects availability and plant utilization
  of minerals.
• ? P critical for seedling development.
• K critical for maintaining legumes.
• Apply 1 3 years before seeding.

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Pasture Soil Fertility Management
Mid-Atlantic Equine Pasture Initiative
Mid-Atlantic Equine Pasture Initiative

• Daniel Kluchinski
• County Agent Assistant Director
• Rutgers University

Paul H. Craig Dauphin County Cooperative
Extension Agent Penn State University
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pH Basics

• Soil acidity or alkalinity is measured by pH
• The pH scale is from 0 to 14
• 7.0 Neutral
• lt 7.0 acidic
• gt 7.0 alkaline or basic
• Crops have specific soil pH requirements for
  optimum growth
• Most pasture grasses and legumes prefer a pH
  range of 6.5-7.0

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pH Basics

• Low pH conditions can cause
• Aluminum toxicities
• Reduced availability of soil nutrients
• Poor conditions for soil microbes
• Deficiencies of calcium and/or magnesium
• Poor soil structure

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pH Basics Limestone

• Limestone is an amendment used to reduce soil
  acidity (raise pH)
• Limestone contains carbonates and oxides of
  calcium and magnesium
• Expressed as CaCO3 or MgCO3

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pH Basics Limestone

• Quality and neutralizing ability
• Depends on origin or source of limestone
• Limestone recommendations are based on Calcium
  Carbonate Equivalent (CCE)
• Can vary from less than 60 to more than 125 CCE
  
• The actual amount of limestone to be applied will
  differ from material to material due to different
  CCE values for each

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pH Basics Limestone

• Limestone particle size affects rate of
  neutralization
• Finer materials react faster
• Pulverized gt ground gt granular
• Ag lime must meet minimum standards and the label
  must provide a guaranteed analysis

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CCE value
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Fertilizer Basics

• Most fertilizers are products that supply
• Nitrogen (N)
• Phosphorous (P)
• Potassium (K)

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Fertilizer Basics Grades

• Grades of fertilizer are identified by three
  numbers, for example
• 10-10-10
• 5-10-5
• 46-0-0
• Numbers represent the percentage, by weight, of
  N, P2O5, and K2O, respectively

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Fertilizer Basics Nitrogen

• Nitrogen is abbreviated as N
• Listed as the first number in fertilizer grade
• 10-10-10
• Critical component of plant proteins
• Required for vegetative growth
• Produces lush, dark green coloration
• Most forms do not remain in the soil, rather they
  have high soil mobility
• N must be annually applied and in methods
  that reduce environmental problems
• Can be fixed by legumes

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Fertilizer Basics Phosphorous

• Phosphorus is abbreviated as P
• Listed as the second number in fertilizer grade
• 10-10-10
• Vital role in plant reproduction
• Essential for root growth and seedling
  development
• Supplied as P2O5
• Limited soil mobility

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Fertilizer Basics Potassium

• Potassium is abbreviated as K
• Third number in fertilizer grade
• 10-10-10
• Important in many chemical processes in plant
  growth
• Important for disease resistance, overall plant
  health, and winter hardiness
• Supplied as K2O
• Little soil mobility

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Fertilizer Basics Grades

• Multiply the total weight of fertilizer material
  by the percentage for each nutrient to determine
  actual nutrient content
• For example, an 80-pound bag of 10-10-10
  fertilizer contains
• 8 lb. of N
• 8 lb. of P2O5
• 8 lb. of K2O

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Fertilizer Basics Grades

• Fertilizer recommendations are provided based on
  pounds of nutrients needed for the given crop
  based on the soil test levels and expected yields
• Application timing and method will be provided in
  the recommendation

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Fertilizer Basics Manures

• Manures are a source of nutrients
• Typical nutrient composition of horse manure (per
  ton)
• 12 lb. of N
• 5 lb. of P2O5
• 9 lb. of K2O
• A manure analysis will provide data on specific
  nutrient concentrations

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Fertilizer Basics Manures

• Manure should be applied to fields only if
  fertility levels justify their application.
• Manures can be composted to reduce their volume
  as well as any pathogens contained within.

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Pasture Fertility Management

• Soil testing data and recommendations should be
  followed to develop a fertility and pH management
  plan
• Recommendations differ, depending upon
• New seeding or established stand
• Grass and legume species
• Current fertility levels

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Pasture Fertility Management

• Establishing New Seedings
• Last chance to build nutrient levels into the
  optimum range throughout the rooting zone
• At this time, tillage may be used to incorporate
  and mix lime and fertilizer into the soil
• This is particularly important if the soil pH or
  phosphorus level is very low
• Fertilizer and lime usually broadcast onto the
  field and disked or tilled into the soil prior to
  seedbed preparation

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Pasture Fertility Management

• Establishing New Seedings
• Different application procedures are used
  depending on the amount of lime or fertilizer to
  be applied
• If large amounts are recommended, apply as a
  split application -- plow down ½ the amount and
  surface apply the remaining ½
• If small amounts are recommended, apply the
  entire amount on surface

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Pasture Fertility Management

• Maintenance of Established Pastures
• Amount of N, P2O5, and K2O recommended depends on
  current soil fertility levels and the type of
  pasture species being grown.
• N not recommended for pastures containing gt25
  legumes.
• Heat sensitive grasses such as Kentucky bluegrass
  and timothy require different fertilizer rates
  and application times than less sensitive grasses
  such as tall fescue and orchardgrass.

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Pasture Fertility Management

• N -- Established Grass Pastures
• Rate based on expected yield
• Generally 40 lb N/acre/ton of expected yield is
  recommended
• Equivalent to approximately 100 to 250 lb N/acre
  annually
• Timing split applications
• Late winter/early spring (green up)
• Mid- to late May
• Late Aug/early Sept

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Pasture Fertility Management

• P and K --Established Grass Pastures
• Application rates based on soil nutrient levels
  and expected yields
• Generally 10 - 20 lb P2O5 and 45 - 60 lb K2O
  removed/ton of forage
• Timing
• For low fertilizer rates, timing not critical
• High rates should be split for maximum efficiency
  
• ½ in mid- to late May
• ½ in late Aug/early Sept

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Pasture Fertility Management

• Long-Term Management
• Recommended fertilizer applications should be
  followed for a 2- to 3-year period.
• Soil should be retested every 2 to 3 years to
  determine
• Soil pH and fertility status
• If any change in fertilization and pH management
  is necessary

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Pasture Fertility Management

• Long-Term Management
• All soil test reports should be kept on file for
  historic reference
• All application records should be retained for
  future reference
• Include a field-by-field inventory
• Record lime and fertilizer analyses
• and rates
• Record manure applications
• Reference this information and follow the
  recommendations to improve and maintain soil
  fertility

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Conclusions

• Optimum production of pasture plants depends on
  optimum pH and fertility management
• Soil testing is the foundation for sound soil
  fertility management
• Timely applications of necessary lime and plant
  nutrients will provide pasture plants with
  optimum fertility conditions
• Proper management is essential to reduce
  environmental risks or degradation