Soil Fertility and Pasture Fertilization

1. Soil Fertility and Pasture Fertilization Les Vough Forage Crops Extension Specialist Emeritus INAG 116

2. Causes of low pasture productivity:  Lack of adequate fertilization.  Poor grazing management.  Unproductive species.

3. Adequate Fertilization Soil test every 2-3 years. Lime and fertilize according to soil test recommendations.

7. 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.

13. 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.

14. Mid-Atlantic Equine Pasture Initiative Mid-Atlantic Equine Pasture Initiative Pasture Soil Fertility Management Daniel Kluchinski County Agent & Assistant Director Rutgers University Paul H. Craig Dauphin County Cooperative Extension Agent Penn State University

15. pH Basics • Soil acidity or alkalinity is measured by pH • 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

16. 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

17. 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

18. 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

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

20. CCE value

21. Fertilizer Basics • Most fertilizers are products that supply: • Nitrogen (N) • Phosphorous (P) • Potassium (K)

22. 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

23. 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

24. 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

25. 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

27. 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

28. 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

29. 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

30. 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.

31. 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

32. 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

33. 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

34. 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 >25% 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.

35. 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

36. 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

37. 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

38. 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

39. 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