That pasture is just a sea of green grass, right? Not quite, it’s likely a mix of grasses and broadleaf forbs (herbaceous flowering plants). Even if grasses are the predominant plant type in your pasture, it’s wise to be aware of what other species are present and if they’re desirable as pasture plants. Some weeds are fairly innocuous, while others can be serious problems. The more problematic weeds are competitive with desirable plants or they may be toxic to your animals.

The trend in plant cover is also important. Trend describes changes in the vigor of plants or the changes in area occupied by various species. If more bare patches are visible this year than in past years, the trend is negative. More bare ground increases the risk of soil erosion and exotic plant invasion. It is best to avoid both these situations.

Can we have healthy, and native, pasture?

Some landowners would like to grow productive pasture and host native grasses. Plant communities, particularly west of the Cascades, have been drastically altered in the era since European American migration began in the mid-1800s. Land has been used intensively for many agricultural purposes and many native plant species do not fair well under these conditions. As a result, some remnant meadow communities exist and their component grasses are present in a few locations but not in large quantity. Selection and breeding of grasses native to areas west of the Cascades is not common practice. Pasture managers in the Pacific Northwest rely on varieties of European grass species because they are familiar and have been selected for their vigor under grazing pressure, tolerance of hoof action, and absence of toxins.

East of the Cascades, many native grasses are present on rangeland. A few of these include various wheat grasses, squirrel tail, Idaho fescue, and Basin wild rye in areas where soils are wetter. Managing these grasses and their associated shrubs involves different practices than in the higher rainfall areas of the West. Climatic and soil factors dictate the timing of use of native range. Irrigated pasture and hay production use many of the grass species found west of the Cascades.

Assessing the composition of pasture

Once you know that the soil is stable, the next step in assessing a piece of property is to complete a plant inventory. In turn, knowing what plants are present can indicate soil condition. Sampling techniques can be used to get an accurate picture of what is present by making a visual assessment on a grid or transect lines. If you have undesirable plants, a.k.a. weeds, you need to decide what efforts to get rid of them are needed.

Many plants in small amounts are not a concern. An example is English daisy. It is very short in stature and will not increase in area (plant cover) if shaded by healthy grasses and if the soil remains healthy. True dandelion is also not a concern because it is palatable to all livestock. On the other had, false dandelion is of concern. Once learned, distinguishing the thin-leaved true dandelion from the fleshy and hairy-leaved false dandelion is easy.

Ordinarily, horses will not select false dandelion in large quantity and so it is not a problem for many landowners even where it is present in small quantities. In other cases, individual horses may develop a habit of eating false dandelion because the pasture is degraded and little other vegetation is available. Ingesting large amounts can lead to stringhalt.

Controlling a pest plant when it first appears in pasture will save hours of work and cost in the long run. Spring is a critical time to have a close look at what is growing because many perennial plants break dormancy as day length increases and soil temperatures increase. Checks later in the year are also important as the timing of emergence and growth of annuals varies among species and varieties.

If you are monitoring your pasture, you will notice when a problem plant is present and the area it occupies. Then you can choose an appropriate control technique and prevent the plant from increasing in number and/or area. Control methods may include complementary grazing, targeted grazing, herbicide application, mowing or other mechanical methods like pulling. The most effective managers use a combination of these tools.

Which plants are desirable in a pasture? Why?

Horse pasture seed mixes include several grass species and often a small percentage of a legume such as clover. Let’s start by considering the grasses. We use cool season grasses in the Pacific Northwest because they are best-suited to our climate. Most of our rain falls from October to May. Root growth occurs primarily in fall and top growth is greatest in spring and summer. As the soil dries out in summer and warms up, grass growth slowly declines until another dose of rain wets the soil. This climatic pattern lends itself to the use of many European species including bluegrasses, rye grasses, and orchardgrass, to name a few.

Endophyte-free varieties of tall fescue comprise a large percentage of the total seed weight in many horse pasture mixes. Tall fescue has historically been favored by stockmen because it tolerates poor soils and has a hardy root structure. It begins to grow earlier in the year than orchardgrass. Many varieties of orchardgrass are included in pasture seed also. Orchardgrass develops a large root system which is good for soil and helps the plant withstand grazing pressure.

Along with several species of grass, to ensure varied timing of forage supply, some seed mixes contain a small portion of clover. Again, this legume has benefits for both soil health and your animals. If the proper soil bacteria are present, clover fixes nitrogen in the soil and thereby makes it available to other plants. The clover itself is a good source of protein for livestock and horses. It is traditionally a small portion of a mix to avoid bloat problems that occur in cattle and sheep.

Horses require relatively less protein than other livestock for most of their lives because they are not producing large quantities of milk or growing muscle for meat, like commercial livestock species. It is possible that most of the protein requirement can be met through the pasture forage in summer. Naturally, this varies with the age and work the horse is doing. White clover is the most commonly used variety. It is distinguished from other clovers by its white flowers and white ‘halo’ on the upper surfaces of the leaflets. It is also considered a weed by gardeners and is often found where it has escaped from pasture cultivation.

Kentucky bluegrass is also a common species in pasture mixes because it is palatable and grows rhizomes (underground stems) that allow it to spread and maintain vigor. Even if grazed heavily, such that seeds cannot form, it spreads by the vegetative rhizome and will persist.

What management practices improve pasture?

Proper timing of grazing is important to protect soil from compaction and to allow plants to establish healthy root systems, as mentioned in last month’s article. Soil tests to determine nutrients present or deficient will guide you in fertilizing practices as well. Properly composted manure can be a good source of the nutrients your pasture needs to host healthy plants. This varies depending on the specifics of each site.

Most of us are not seeding new pasture in a freshly tilled seed bed, yet the same plant seeds are useful for over-seeding a pasture needing rehabilitation. One exception is timothy, which makes great hay but often does not stand up to hoof action.

Consider that every time we place hay on the ground we may affect future pasture composition. If you feed mature hay on pasture or in paddocks, be certain the seeds in those flakes are species you want to see next year and in 10 years! This method of feeding can be very effective for re re-seeding pasture with desired species at the same time. However, buying cheap hay which contains weed seed is not a deal. Feeding weedy hay results in endless work and poorer pasture in future years.

Millions of dollars are spent annually controlling weeds in field crops, meadows, and wild lands across the United States. On some public lands you have to feed certified weed-free hay in order to be allowed access to trails and camp sites. Private land owners who have dealt with costly weed problems are also choosing this option. Because this is such an important issue, the Oregon Department of Agriculture offers a certified weed-free hay program. You can purchase hay from a certified grower to ensure you do not contribute to the dispersal and establishment of more weeds. Sources of this hay are available at: http://oregon.gov/ODA/CID/weed_free_forage.shtml. Your animals can eat good forage while you are acting as a steward of our natural resources.

Consider the neighbors

Most of the species we associate with healthy pasture west of the Cascades are of European origin. This is true of many of our food and ornamental crops as well. These species are not a problem simply because they are exotic. If properly managed, we can have agricultural land and native pristine areas. Meeting both goals requires that all of us are diligent and well-informed managers.

The pasture species mentioned in this article are productive under grazing regimes and support ecological functions of water infiltration and soil stability while also being nutritious for horses, livestock, and wildlife. In some locations, the virtues of these plants are also the reasons some and managers oppose their use.

Hardy plants, with high rates of growth or means of growth to overcome competition, can also become invasive. Tall fescue is commonly seeded in Western Oregon due to its growth characteristics but caution may be in order if your land borders a preserve or other area where managers are trying to support a native plant community.

Grasses are wind-pollinated and seeds are dispersed by wind, wildlife and human activity. Consider your own situation and all the land uses in your area. Always talk with managers of land adjoining yours so that your management goals are not in conflict. This collaborative approach may even allow you to reduce costs and complete improvements that otherwise would not be possible. Shared use of equipment for seeding, fertilizing or weed control are just a few of the benefits that may result.