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 Management Daniel Kluchinski County Agent & Assistant Director Rutgers University Mid-Atlantic Equine Pasture Initiative Paul H. Craig Dauphin 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

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 CaCO 3 or MgCO 3

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 o o  Numbers represent the percentage, by weight, of N, P 2 O 5, and K 2 O, respectively

Fertilizer Basics: Nitrogen  Nitrogen is abbreviated as “N”  Listed as the first number in fertilizer grade o  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 grade o  Vital role in plant reproduction  Essential for root growth and seedling development  Supplied as P 2 O 5  Limited soil mobility

Fertilizer Basics: Potassium  Potassium is abbreviated as “K”  Third number in fertilizer grade o  Important in many chemical processes in plant growth  Important for disease resistance, overall plant health, and winter hardiness  Supplied as K 2 O  Little soil mobility

Fertilizer Basics: Grades  Multiply the total weight of fertilizer material by the percentage for each nutrient to determine actual nutrient content o For example, an 80-pound bag of fertilizer contains  8 lb. of N  8 lb. of P 2 O 5  8 lb. of K 2 O

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 P 2 O 5  9 lb. of K 2 O 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 Seedings o 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, P 2 O 5, and K 2 O 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 Pastures o 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 lb P 2 O 5 and lb K 2 O 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 Management o All soil test reports should be kept on file for historic reference o 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