Soil Fertility and Pasture Fertilization Les Vough Forage Crops Extension Specialist Emeritus INAG...
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Transcript of Soil Fertility and Pasture Fertilization Les Vough Forage Crops Extension Specialist Emeritus INAG...
Soil Fertility and
Pasture Fertilization
Les Vough
Forage Crops Extension Specialist Emeritus
INAG 116
Causes of low pasture productivity:
Lack of adequate fertilization.
Poor grazing management.
Unproductive species.
Adequate Fertilization
Soil test every 2-3 years.
Lime and fertilize according to soil test recommendations.
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.
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.
Pasture Soil Fertility Pasture Soil Fertility ManagementManagement
Daniel Kluchinski County Agent & Assistant
Director
Rutgers University
Mid-Atlantic Equine Pasture InitiativeMid-Atlantic Equine Pasture Initiative
Paul H. CraigDauphin County Cooperative
Extension Agent
Penn State University
pH Basics
Soil acidity or alkalinity is
measured by pH
o The pH scale is from 0 to 14
7.0 = Neutral
< 7.0 = acidic
> 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
pH Basics
Low pH conditions can cause:
o Aluminum toxicities
o Reduced availability of soil nutrients
o Poor conditions for soil microbes
o Deficiencies of calcium and/or magnesium
o Poor soil structure
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
pH Basics: Limestone
Quality and neutralizing ability
o Depends on origin or source of limestone
o Limestone recommendations are based on Calcium Carbonate Equivalent (CCE)
o Can vary from less than 60 to more than 125 CCE
o The actual amount of limestone to be applied will differ from material to material due to different CCE values for each
pH Basics: Limestone
Limestone particle size affects rate of
neutralization
o Finer materials react faster
o Pulverized > ground > granular
Ag lime must meet minimum standards and
the label must provide a guaranteed analysis
CCE value
Fertilizer Basics
Most fertilizers are products that
supply:
o Nitrogen (N)
o Phosphorous (P)
o Potassium (K)
Fertilizer Basics: Grades
Grades of fertilizer are identified by three numbers, for example:o 10-10-10o 5-10-5o 46-0-0
Numbers represent the percentage, by weight, of N, P2O5, and K2O, respectively
Fertilizer Basics: Nitrogen
Nitrogen is abbreviated as “N” Listed as the first number in fertilizer grade
o 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
Fertilizer Basics: Phosphorous
Phosphorus is abbreviated as “P” Listed as the second number in fertilizer
gradeo 10-10-10
Vital role in plant reproduction Essential for root growth and seedling
development Supplied as P2O5
Limited soil mobility
Fertilizer Basics: Potassium
Potassium is abbreviated as “K” Third number in fertilizer grade
o 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
Fertilizer Basics: Grades
Multiply the total weight of fertilizer material by the percentage for each nutrient to determine actual nutrient contento For example, an 80-pound bag of
10-10-10 fertilizer contains 8 lb. of N
8 lb. of P2O5
8 lb. of K2O
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
Fertilizer Basics: Manures
Manures are a source of nutrients o Typical nutrient composition of
horse manure (per ton) 12 lb. of N
5 lb. of P2O5
9 lb. of K2O
o A manure analysis will provide data on specific nutrient concentrations
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.
Pasture Fertility Management
Soil testing data and recommendations should be followed to develop a fertility and pH management plan
Recommendations differ, depending upon:
o New seeding or established stand
o Grass and legume species
o Current fertility levels
Pasture Fertility Management
Establishing New Seedingso 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
o Fertilizer and lime usually broadcast onto the field and disked or tilled into the soil prior to seedbed preparation
Pasture Fertility Management
Establishing New Seedings o 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
Pasture Fertility Management
Maintenance of Established Pastures
o Amount of N, P2O5, and K2O recommended depends on current soil fertility levels and the type of pasture species being grown.
o N not recommended for pastures containing >25% legumes.
o 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.
Pasture Fertility Management
N -- Established Grass Pastureso 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
o Timing – split applications
– Late winter/early spring (green up)
– Mid- to late May
– Late Aug/early Sept
Pasture Fertility Management
P and K --Established Grass Pastures
o Application rates based on soil nutrient levels
and expected yields
– Generally 10 - 20 lb P2O5 and 45 - 60 lb K2O
removed/ton of forage
o 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
Pasture Fertility Management
Long-Term Management
o Recommended fertilizer applications should be followed for a 2- to 3-year period.
o 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
Pasture Fertility Management
Long-Term Managemento All soil test reports should be kept on file
for historic referenceo 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
o Reference this information and follow the recommendations to improve and maintain soil fertility
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