Posted: March 29, 2012
By: Donna Foulk, Equine Extension Educator
Adopting good pasture management practices is increasingly important as stocking density or number of horses per acre increases. In most areas, pastures can be maintained with very little management at stocking densities of 2-4 acres per horse. At higher stocking densities, good management is necessary to maintain high quality pastures. Without adequate pasture availability, horse owners need to feed hay to help meet the animal’s nutrient requirements and prevent overgrazing of the pasture. The pasture management techniques outlined below can be used to help you maintain healthy, productive pastures for your horses.
Test Your Soil
Proper fertilization is a critical step in maintaining high quality forage in pastures. Soil nutrient and pH levels are extremely variable from farm to farm. It is important to accurately determine the nutrients and pH of the soil for each pasture and field on the farm by performing a soil analysis. Consult your local Extension office or analytical laboratory for soil test kits and directions on how to collect a soil sample. It is important to collect a representative sample so the recommendations you receive from the analysis are applicable to your entire pasture instead of only a small area. After submitting the sample, the lab will provide a complete report which documents soil nutrient levels and pH. The report will also provide recommendations for the application of fertilizer and lime.
Apply Fertilizer and Lime Based on Soil Tests
Maintaining proper soil pH is essential to the production of healthy forages. Soil pH is a measure of the acidity of the soil. A pH of 7 is neutral, a pH greater than 7 is basic, and a pH less than 7 is acidic. Grass forages perform well in soils with a pH between 6 and 7. Legumes require a higher pH or more basic soils. Acidic soils are detrimental to plant health and productivity because acidic conditions limit the availability of many soil nutrients. Acidic soils may also mobilize metals and other materials in the soil that may be harmful to plants. A soil analysis report will provide the soil pH along with recommendations for the application of lime. Lime is basic in nature. Therefore, application of lime increases soil pH and makes the nutrients in the soil available to the plant.
Plants require many nutrients for growth and reproduction. Your laboratory report will tell you the specific nutrients to apply on your farm. The three primary nutrients on your report will be nitrogen (N), phosphorus (P), and potassium (K).
For grasses, nitrogen is a critical nutrient for forage quality and growth. In contrast, legumes such as clovers and alfalfa are able to “fix” nitrogen or take nitrogen from the air and convert it to a form which they can utilize. Therefore, legumes do not have the same requirement or response to nitrogen as grasses. For grasses, adequate nitrogen is associated with a dark green color and vigorous, vegetative growth. A nitrogen deficiency is indicated by a pale green or yellow color and poor growth. Heavily grazed pastures require approximately 100 to 150 pounds of nitrogen per acre per year. Too much nitrogen applied at one time can cause animal health and water quality problems, so nitrogen application should be divided into multiple applications. A good rule of thumb is to apply 50 pounds per acre at the onset of the spring growing season. An additional 50 pounds of nitrogen per acre should be applied in early fall. Summer applications are appropriate if environmental conditions such as proper temperature and moisture, are allowing the pasture grasses to grow. Summer applications should be restricted to 30 pounds per acre and should match forage growth.
Phosphorous and potassium are also important nutrients. Phosphorus improves forage quality and root development. A well-developed root system increases the plant’s ability to acquire nutrients and water from the soil. Adequate potassium improves the plant’s ability to survive periods of stress such as drought or freezing winter temperatures. A potassium deficiency is characterized by poor growth, reduced disease resistance, and reduced winter-hardiness.
When purchasing fertilizer, the nutrients in the fertilizer are stated on the label. The percentage of nitrogen, phosphorus, and potassium are expressed as a ratio, by weight. The nitrogen, phosphorus, and potassium ratio is listed in that order. For example, a 10-10-20 fertilizer contains 10% nitrogen, 10% phosphorous, and 20% potassium. One hundred pounds of this fertilizer contains 10 pounds of nitrogen (10% of 100 pounds), 10 pounds of phosphorous (10% of 100 pounds), and 20 pounds of potassium (20% of 100 pounds). Fertilizer is available in many ratios. Commonly available fertilizer ratios include: 10-20-20, 15-15-15, 10-10-10, 5-10-5, 5-10-10, 10-20-10, 10-20-20, 20-10-10, and 46-0-0.
In addition to these three primary nutrients, grasses also require some additional micro and macro nutrients, such as sulfur, iron, and boron. Since many soils have sufficient levels of these nutrients, it is wise to test soil concentrations if you suspect that a deficiency might occur. Most soil laboratories will test and provide recommendations for these nutrients for an additional fee. Caution: Fertilizers can be toxic to livestock. Animals should be kept out of the pasture when fertilizer is applied and should not be returned to the pasture until all of the fertilizer has leached into the soil. Application of fertilizer prior to rainfall or irrigation can reduce the time the animals have to be out of the pasture.
Pasture renovation is an effective way to improve stand density or introduce new species into existing pastures. Following a few simple management techniques goes a long way to promote the establishment of new seedings.
When renovating pastures, it is very important to select the correct forage species. Always match the forage species to your site conditions, management level, and the stocking rate of your pastures. Forage species vary greatly in terms of their ability to tolerate poor soil fertility, low pH levels, wet and dry soil conditions, and intense grazing. There are many new forage varieties available that have been developed to match specific pasture conditions. Most pasture seed mixes contain a variety of species. If you purchase high quality seed, it is expected that several of the species in the mix will thrive in a pasture even with variable management or environmental conditions. To ensure quality, it is important to purchase seed from a reputable dealer and purchase seed mixtures formulated for horse pastures. Many turf grasses, including fescue and perennial ryegrass, contain harmful endophytes. An endophyte is a fungus that lives within the plant and produces a chemical that fights insects and diseases. Endophytes can be beneficial to plants because they improve persistence, but specific endophytes may have a detrimental impact on animal health. Not all endophytes are harmful to animals. Therefore, it is important to purchase endophyte-free seed or seed with an endophyte which is safe for animals to consume.
When you have identified the seed you are going to purchase, select the appropriate time of year to plant. In general, spring and fall are ideal seasons to plant. In regions prone to summer drought and with limited irrigation, early fall seedings are generally more effective.
Proper soil preparation promotes the growth and survival of new seedlings. To ensure adequate pasture fertility and pH, submit a soil sample to the lab and fertilize and lime as recommended. Prior to seeding, control weeds in your existing pasture and mow or graze the existing pasture to reduce competition
Pastures can be renovated by using a no-till drill or a broadcast seeder. Renovating pastures using a no-till drill increases the chances for good germination and establishment. A no-till drill cuts a slit in the ground, drops the seed in the slit, covers the seed, and firms the soil. When using a drill, do not plant the seed too deep; maximum planting depth for grasses is ¼ inch. To locate a no-till drill, contact your local equipment company.
With proper soil preparation and management, broadcasting can also be an effective seeding method. In general, just broadcasting seed onto unprepared soil does not result in enough seed-to-soil contact to allow for high germination rates and good establishment. Therefore, to promote establishment of broadcast seedings, the soil surface must be disturbed prior to planting. To loosen the soil, scratch the surface with a disc or a harrow. Then, broadcast the seed using a spin-seeder or by hand. After broadcasting, roll the pasture to ensure adequate seed-to-soil contact. If irrigation is available, irrigate lightly after seeding to keep the soil surface moist until the grass germinates and each plant has 2 to 3 leaves per seedling. Then, irrigate according to local recommendations for pastures.
To ensure the new seedlings have time to establish, control animal access to the new pasture. Once the new seedlings are firmly rooted, lightly graze or mow multiple times. Grazing or mowing grasses promotes tillering and the development of the root system. Initial grazings should begin when the grass is 6 inches tall and animals should be removed when the grass has been grazed to 3 inches. For the initial grazings, allow short-term access in favorable weather and provide your animals hay to prevent overgrazing.
Once established, proper grazing management by controlling the intensity and timing of grazing improves forage quality and long-term productivity. Grazing height is a simple measure to control the duration of grazing - when to graze and when to remove the horses from a pasture. A good rule of thumb is to allow pasture to reach 6 to 8 inches and then graze to 3 to 4 inches. A rotational grazing system allows you to control the timing of grazing.
Information on forage species, establishment and management, soil fertility management and weed/insect management can be found in the Penn State Agronomy Guide on line