2011 21.2 Mindful Pasture Management
A pasture is a complex, dynamic biological system that is influenced by many factors. The best managers frequently monitor their pastures and continuously adapt their practices. A good pasture management plan gets modified as needs change. Doug Warnock, retired WSU extension agent in Kittitas County, says in his Small Ranch Manual, “The presence of livestock on the land and its impact on the environment is totally dependent upon the humans in charge.”
Dryland versus irrigated fields
One can find wooded pastures, irrigated pastures, and dryland pastures, each with a place in the spectrum of usability. Wooded pastures may have their greatest value as wildlife habitat, part of a watershed, timber production or pure esthetics. At the same time, it is possible to graze the understory, particularly if there is good forage or it has been seeded.
Dryland pastures are the most fragile and have the lowest livestock carrying capacity. Most are suitable for primarily shortterm, light spring or fall use, so as not to adversely impact the vegetative cover. Native plants are easily over-utilized resulting in their displacement by noxious weeds and soil movement downslope, which negatively impacts water quality. Even with the best of management practices, we can only expect a fraction of the production of irrigated pastures.
Irrigated pastures can be the most stable and productive from an economic standpoint. There are two types of irrigated pastures: improved and unimproved. Improved pastures are those that have had an introduction of non-native plants. Unimproved pastures are those that have evolved under their own systems to plants that perpetuate themselves. Climate, wind, heat, season, types of forage, pasture use, stage of growth, and precipitation all affect the timing of irrigation. Knowing how much water is available for irrigation and the water requirements of the crop being grown makes an efficient irrigator. Learning the best way to irrigate a field requires a lot of trial and error and a lot of seasons. It is important to study and observe the effectiveness of an irrigation system and make adjustments based on observed results.
With conventional use, most pastures have bluegrass (Poa spp), quackgrass (Agrypyron repens), some short perennial clovers, Meadow foxtail (Alopeceurous pratensis), Redtop (Agrostis spp), some sedges and rushes in the wetter areas, and an assortment of forbs (broadleaf plants). These pastures can be made many times more productive by the introduction of new species and a change in management.
Annual precipitation is a major factor in determining the kind of pasture that is possible. While irrigation has made many an area more productive than it was prior to the enabling water source, dryland pastures are still productive and can yield significant forage.
Who’s eating what ?
Management of the grazing pattern is key to maintaining a high yielding and high quality pasture. If the pasture is not grazed properly, poor production and low quality forage can result. Management needs to be flexible enough to adapt to seasonal variations and to change when the monitoring of both the plants and animals indicates a problem. Doug Warnock points out in a past Capital Press column, “The key to the impact that grazing animals have on the land is related to the time that they have access to any particular plant and the time that the plant has to regrow before the animals return.”
There are seasonal variations in the growth rate of different forage plants. Normally, the largest and most rapid growth for cool season grasses occurs in the first two to three months of the growing season, then growth tapers off as the temperatures get warmer. Alfalfa, clovers and some of the warm season grasses produce more of their growth later in the warmest part of the growing season and will compensate for the hot weather slump of cool season grasses.
GOT PHOTOSYNTHESIS?
Seasonal changes in production can be compensated for by adjusting the number of animals and length of time they graze a particular area or by harvesting part of the forage as hay or silage during the heavier growth period.
It is important not to begin grazing too early in the spring. When the pasture first greens up and begins to grow, it is tempting to turn livestock out to begin grazing, but too early turn-out to graze can cause problems. The plants need to develop enough leaf surface to support the photosynthesis required to replenish their reserves and replace part of their root systems. The stubble height remaining in grazed pastures is more important than previously thought. Basal leaves which are actively photosynthesizing are vital to the plant’s regrowth potential, and to the recovery of crown tissue. The presence of basal leaves results in vigorous plants with extensive leaf surfaces that help reduce the amount of sunlight reaching the soil surface. Maurice Robinette of the Lazy R Ranch outside of Cheney puts it this way, “We try to put the animals at the right place at the right time for the right reasons. We match the nutritional requirements of the animal to the forage availability of the land. When properly done, planned grazing restores damaged grasslands to health and sustainability, increasing the productivity and profitability of ranches.” (Tilth Producers Quarterly, Summer 2010)
THE FOUR INCH RULE
A rule of thumb for mixed species grass and legume pastures is to allow at least four inches of growth before the first grazing in the spring. Subsequent grazing should be done following more than four inches of growth. If plants are grazed too low, they will be weakened and will take longer to recover. For grass plants that produce nearly all reproductive or seed head tillers, graze first spring grass early, then remove livestock until after the plants tillers are beyond the boot growth stage of development. A plant that is grazed too low or at the improper time is not able to restore its roots, will be less competitive and is much more subject to injury from other environmental stresses. Pasture plants provide soil cover that protects against excessive soil drying and weed encroachment. Weakened pasture plants can result in drier soil conditions and weed infestations.
Grazing Methods
There is great variation in the nutrient requirements of livestock of different species, size, and stages of gestation or lactation. For example, a 1,100 pound beef cow requires about 20 percent more protein and energy after she has calved than she does in late gestation. A high-producing dairy cow requires a high level of top quality grass-legume forages, but a dry cow will do well on a lower quality, straight grass pasture.
Overgrazing, the most common reason for loss of good pasture stands, results in poor quality, low-producing pastures. Under-grazing negatively influences pastures by lowering productivity and forage quality. Methods to reduce both over and undergrazing have been practiced through the utilization of one or more grazing approaches.
Continuous grazing is considered the more traditional system of grazing livestock. It is, however, the least efficient system of grazing an irrigated pasture. Stocking rates must be lower with continuous grazing. It results in less total forage production, increased wasted forage, increased soil compaction, increased weed problems, and uneven utilization of forage plants. With low stocking rates, individual animal performance or weight gains can be high. The major advantage of continuous grazing is that the livestock producer is free from decision-making over the growing season.
Rotational grazing requires the livestock producer to make decisions and to practice close control of the grazing animals to ensure proper pasture utilization. The results of rotational grazing include high total herd performance and high land performance, but not necessarily the highest gain per animal. For more efficient grazing on productive soils, divide pastures into four or more sections or paddocks. Set up a rotation that concentrates all the animals on one section, while the other sections are allowed a rest period for regrowth. Pasture plants that have mostly reproductive tillers and plants that tend to grow more upright should be grazed by rotational methods because these plants need time between grazing periods to regrow. Less forage is wasted and weed problems are usually less with rotational grazing. Rotational grazing does incur additional costs. The system requires more fencing, either permanent or temporary, along with additional gates and stock watering troughs to help with animal handling and efficiency.
High intensity, short duration grazing is an intensification of the common rotational grazing system. Another name for this is planned grazing. This is an approach to pasture management that includes the manager’s long term goal for the land, while at the same time providing forage for animal feed. The pasture manager is not only a livestock producer, but also a “grass farmer”. The “grass” is a crop that is harvested by the grazing animals. The process of forage production is possible only because of the plants’ abilities
to use energy from the sun to produce plant mass. The pasture manager is involved in a natural process in which the animals are harvesting the product from solar energy.
The amount of time and effort that the manager has to devote to managing the pasture will depend up the goals and other priorities and responsibilities. The optimal return and greatest positive impact on the land will occur from a more intensive type of management, one that requires more time in monitoring and moving the animals. A recent Farm Walk to the Lazy R Ranch near Cheney in May of 2010 illustrated these concepts very graphically.
Plant Biodiversity
The best in forage quality and quantity comes from a pasture that has a good biodiversity, meaning a variety of grasses, legumes, and forbs. Each species provides different nutrients in differing amounts, so plant diversity is more apt to provide a balanced diet. A combination of grasses and legumes helps to make the amount of feed available more uniform throughout the growing season. Grasses produce more during the cooler spring and fall seasons, while legumes produce more during the warmer summer temperatures. Whenever possible, management practices should promote plant diversity in the pastures.
Developing a Pasture Sense
In order to implement a planned grazing program, one must develop a pasture sense, which includes an understanding of the four natural processes that take place within the pasture ecosystem: the water cycle, the mineral cycle, plant succession, and solar energy flow. Familiarity with the natural growth patterns of plants is also helpful. When these processes are integrated and effective, they provide for high plant diversity and a high level of forage production. The effectiveness of these four processes is greatly impacted by the actions that the manager takes in moving animals during the course of the growing season. Planned grazing management will make good utilization of the impact of the grazing animals to keep pastures healthy.
Forage production is the business of changing sunlight into feed for animals. There are various activities that can impact the quality of the forage. Pasture improvement by seeding, irrigation, stock management, and weed control all contribute to whether or not one has a high quality pasture to offer their livestock. How one manages the various factors and the amount of effort and time invested will yield proportionate results.
