Mowing benefits a pasture in many ways. Mowing at regular intervals maintains grasses in a vegetative stage and produces a high quality, uniform pasture. Mowing also promotes tillering of the grass which leads to a dense, leafy sward. In addition to maintaining quality and productivity of favorable species, mowing also helps prevent the growth of weeds. It removes some weed species and reduces the production of weed seeds by others. Mowing at the proper height is important to maintain the health and survival of pasture grasses. Many grass species store their energy reserves in the bottom few inches of the plant, so mowing too low reduces their reserves and limits their ability to regrow. When mowing, maintain a mowing height of 2 to 3 inches if your pasture is composed primarily of fine-bladed, short grass species such as perennial ryegrass and bluegrass. Mow to maintain a slightly higher level of 3-5 inches if you pasture is composed primarily of taller species such as orchardgrass or timothy.
Proper pasture management leads to high quality, productive pastures that can supply excellent nutrition for horses. Pasture management can be a challenge because of continually changing environmental conditions and fluctuations in horse populations on farms. 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.
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.
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.
Soil fertility is a complex subject. 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 use. 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.
Weeds can be a serious problem in pastures. Since some weeds can be harmful to animal health, pastures should be managed to minimize the presence of weeds. If you are establishing a new pasture, it is important to address weed issues prior to planting. In established pastures, the most effective weed management technique is to maintain a healthy stand of grasses and legumes which compete with weed seedlings. If weeds continue to be a problem, an herbicide application may be appropriate to suppress them. If weed pressure is high, the conditions which promote weed growth need to be addressed. Herbicide alone will not provide a long-term solution.
The first step in any weed control program is to identify the specific species of weeds in your pasture. If you decide to use herbicides as a weed management tool, it is very important to apply the right product because the efficacy varies by species. An herbicide that eliminates one weed species may have no activity on another weed.
In addition to selecting the correct product, it is important to apply the herbicide at the right time. To ensure the timing of application is effective to control the specific weed, it is important to identify the life cycle of the weed. Perennial weeds live more than one year and are dormant in the winter. The ideal time to control perennial weeds is late summer when the weeds are moving their food reserves into the roots. Canada thistle, curly dock, and milkweed are examples of perennial weeds that commonly grow in pastures.
Annual weeds only live one year, but are prolific seed producers. The parent plant will die but the weed seeds that are produced can germinate and produce many plants the following year. Annual weeds exist as summer annual or winter annual weeds. Summer annual weeds produce seeds in the summer. The seeds survive the winter and germinate the next spring. A think, healthy stand of grasses should be able to out-compete newly emerging weed seedlings in spring. If summer annual weeds do become established, then the mature weeds will be highly visible in summer, since the grasses are slowing their growth at this time due to hot, dry conditions. Mowing can sometimes effectively reduce weed seed production and will help reduce weed pressure. The ideal time to control summer annual weeds with herbicides is in late spring when the weed seedlings are very small. It is a poor decision to use herbicides on summer annual weeds in late summer because the plants have already dropped their seeds and are beginning to die. Examples of some common summer annual weeds are lamb's quarters, ragweed, and pigweed.
Winter annual weeds such as chickweed and mustard also live one year, but germinate from seeds in late summer. Winter annual seedlings appear in pastures in early fall and persist as plants through the winter. Winter annual weeds flower very early in spring, drop their seeds and die. By summer, winter annual weeds are no longer competitive in the pasture. However, the seeds are present and ready to germinate in early fall. Since winter annual weeds are present in spring and fall, when the cool season grasses are rapidly growing, it is rarely necessary to control these weeds. Healthy pasture grasses should be able to prevent the germination of winter annual weed seeds and reduce the survival of any seedlings. If pasture growth is very poor and the elimination of winter annuals is warranted, the best time to control them is late summer, after all of the weed seeds have germinated.
Caution: Pesticides to control weeds should be used at the correct rate and time. When using herbicides, it is critical to follow all label directions and restrictions.
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 1/4 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.
Rotational grazing systems improve the productivity of a pasture. Rotational grazing systems allow grasses time to rest which allows grasses time to restore energy reserves required for growth. In addition to the heavy traffic patterns of horses, the natural grazing behavior of horses is stressful on pastures. Horses tend to feed on grasses in the same area and graze the same grasses over and over because they are the most palatable. In addition, the precision of a horse's lips and teeth allow close grazing of select plants in a pasture. Repeated, close grazing of a grass plant depletes energy reserves, reduces growth, and will eventually kill the plant.
As stocking density increases, the implementation of a rotational grazing system becomes more important to maintain quality, productive pasture. A simple two-paddock system will improve productivity. To set up a simple two-paddock system, put one cross-fence across the pasture and rotate the horses between the two pastures. Turn animals into the pasture when the grass is 6 to 8 inches tall and allow them to graze it down to 3 to 4 inches. Development of a system with more than two paddocks will provide additional improvements in pasture performance.
Additional steps may be required to give grasses adequate rest. During periods when grass growth is limited, restrict access to the pastures and increase the amount of hay fed. In addition, it may be beneficial to incorporate a stress lot into the rotational system. The stress lot may be composed of soil or stone dust or may be planted with a forage mixture specially formulated for higher traffic and grazing tolerance.
Spring and fall are ideal times to plan and implement pasture improvements and improve your grazing system. To help develop a rotational grazing system and maximize the resources on your farm, the first step is to map your farm. Diagram the existing barns, pastures, and permanent fences. Consider layouts which allow you to increase the number of paddocks and still allow you to move your animals easily around your farm. Two examples of rotational grazing systems for one farm layout are presented below.