A popular species may have several desirable characteristics, but if it is not well-adapted to the site, there is little chance for successful establishment. Annual precipitation is the most common determining factor for which species will successfully establish and persist on a given site. Do not select a species that requires more annual precipitation than is typical for the site. Table 2 lists minimum recommended amounts of average annual precipitation for several common dryland species. Another important site factor affecting species selection is soil type. In the intermountain region, key soil attributes include texture, depth, and alkalinity. Table 2 shows which soil characteristics are suitable for each listed dryland species. You can get information on local soil characteristics from the Natural Resources Conservation Service soil survey in conjunction with on-site evaluations, either performed by you or with assistance from a farm advisor, hired consultant, or NRCS conservationist. You will find more information on important soil attributes in the Site Selection section.Seed prices and seed supplies vary from year-to-year depending on production and demand. Typically, native species are more expensive and in shorter supply than common introduced species such as intermediate or crested wheat grass. Seed cost can be a considerable factor on large projects, and it is not uncommon for a native seed mix to cost more than $100 per acre. Although seed can be expensive, vertical racking it is important that you not use less than the recommended seedling rate in order to meet a budget.
When considering costs, always remember that any dryland planting is at the mercy of the weather during the year of establishment. Dry spring weather is not unusual, so when it comes to the cost of seed, decide how much money you are willing to risk in that particular year and bear in mind that a repeat seedling may be necessary in future years.Introduced wheat grasses are the most commonly seeded species in the inter mountain region. They tolerate grazing well, adapt to many soil types, and have good seedling vigor, and the seed is almost always available in adequate supply and at a reasonable price. If you are looking for a reliable, affordable choice, choose the best-adapted wheat grass for your area. On sandy loam soils where precipitation averages 14 or more inches per year, intermediate wheat grass is usually the best choice. On drier sites, pubescent wheat grass is often preferred. Most wheat grass species can be mixed with drought tolerant forbs and shrubs. Table 3 presents some typical seed mixes that are based on introduced wheat grasses and used with the objective of improving livestock forage.There is a long-running debate over the benefits of planting introduced versus native plant species. In the early years of range improvement, introduced species were used almost exclusively for rangeland seedlings. Introduced species have several general advantages over their native counterparts in terms of seed cost, ease of establishment, and tolerance to grazing. For example, when native and introduced grasses were seeded in trials conducted in Siskiyou and Lassen Counties, introduced wheat grasses nearly always outperformed native grasses by a substantial margin with regard to seedling survival and establishment .
The advantages of high seedling vigor and ease of establishment are especially important on sites that are prone to invasion by noxious weeds such as cheat grass, medusahead, or yellow starthistle. Restoration ecologists continue to work on methods to improve seedling techniques for native species, but for now, introduced species have a significant advantage over native species with regard to establishment success.Proponents of native species point to the inherent benefits of maintaining species that are native to a given region, even though those species may be hard to establish. Native species proponents have two common concerns about planting introduced grasses: the lack of natural recruitment of native forbs and shrubs into stands of introduced grasses, which carries with it a reduction in plant diversity and possibly wildlife habitat; and the species’ potential to spread into, and possibly outcompete, nearby native plant communities. The competitive nature of a well-established stand of introduced wheat grasses may impede the establishment of some native species. However, there is no published research clearly demonstrating that grasses native to inter mountain rangelands are measurably more compatible with native shrubs and forbs than are introduced wheat grasses, nor have introduced wheat grasses been observed spreading into intact native plant communities. In actuality, there are many places within the inter mountain region where sagebrush, juniper, and other native species have moved into established wheat grass seedlings. In any case, it is clear that a well-established stand of perennial cool-season grasses is preferable to the weedy annual grasses or other noxious weeds that typically invade range sites where pasture seedlings fail.
Seeding recommendations vary from single grass species to complex seed mixes. Mixes are an attractive choice because they address variations in soil characteristics and provide a diversity of species that offer various benefits to livestock, wildlife, and the suppression of weeds. Managing a seed-mix planting can be quite complicated, however, especially when it comes to weed control and livestock management. On a relatively small homogenous site, a single grass species or a simple mix of a single grass and a forb is often adequate. Single-species plantings are easy to manage and can supply livestock with needed forage. Single-species pastures also allow managers to choose from a wide range of herbicides that they can safely apply for weed control. They also eliminate the potential for uneven livestock grazing based on the animals’ preference of one plant species over the other. Large seedlings that feature more variation in soils may warrant a more complex species mix. Subtle differences in soil and microclimate can be enough to favor one species over another, so by seedling a mixture of several species you can often improve the odds that at least a couple of species will establish over the entire landscape. Furthermore, by planting mixes you can improve biodiversity across the landscape. When deciding on which species to include in a seed mix, choose plants with similar levels of seedling vigor, maturity dates, tolerance to grazing, and palatability. A species mix that varies too widely in these characteristics will usually yield a field where grazing preferences can lead to overgrazing and loss of the most palatable species.Seeding rates vary depending on plant species, site conditions, and seedling methods. Table 2 provides recommended seedling rates for several dryland forage species, assuming optimal site and seedling conditions. When broadcasting seed onto rough or rocky terrain, rolling benches you may want to increase the seedling rate to help compensate for an unavoidable lack of uniformity in seed placement. If weeds are a problem, you can try increasing the seedling rate to improve weed suppression after grass establishment, but you will still need to control weeds throughout the establishment phase. Although increases in the seedling rate can be beneficial, they are no substitute for proper establishment practices. Excessively high seedling rates can even result in the failure of a stand. Soil moisture is a limiting factor, and a high seedling rate can lead to high seedling mortality as plants of the desired species compete with one another for that moisture. Actual seedling rates should be based on the Pure Live Seed Percentage . PLS is a computation that reflects the germination and purity of a seedlot where a PLS of 100 percent equals 100 percent germination and purity. Referring to PLS, you can accurately compare different seed prices and know that you are sowing at the correct seedling rate. To determine the PLS for a seedlot , you multiply the seed germination percentage by its purity percentage and then divide by 100. Germination and purity percentages are listed on the seed bag along with percentages of weed seed and inert matter. Avoid buying seed that contains noxious weeds or high levels of inert matter and aim for a PLS above 80 percent.
To convert the recommended PLS seedling rate to a bulk seedling rate, divide the PLS seedling rate by the seedlot’s PLS percentage and then multiply by 100.The fall seedling period runs from September to early November. Seeding at this time takes advantage of growth during the coolest, wettest time of year, when plant water needs are low. By seedling perennial grass at this time, you can give the plants a better opportunity to become established before moisture stress occurs. There are several risks and problems associated with seedling in both early and late fall, however. Early fall seedling. A dryland pasture crop seeded early in the fall can fail if there is sufficient rainfall for germination in early fall but it is followed by an extended dry period. The seed germinate with the initial rainfall, but can then desiccate and die if no subsequent rainfall comes soon enough. Late fall seedling. The chances of more continuous rainfall are greater for seedlings made later in the fall. When you seed late in the fall, however, temperatures may be so cold that plants cannot germinate or become well established before the onset of winter. On some soil types there is a risk of frost heaving of small seedlings as a result of winter freeze-and-thaw cycles. An additional problem with fall seedlings is that winter annual weeds, particularly grasses, generally emerge at the same time as the plants you have seeded. Winter annual weeds grow rapidly, often outcompeting perennial grass seedlings, and unfortunately there are few ways to control these weeds after crop emergence . Despite the risks and the potential for weed problems, fall may be the best time to seed a dryland pasture, especially in areas where the soil is too wet for planting in spring. Seeding in late fall also works best on alkali soils, where it allows seeds to take full advantage of the diluting effect of winter moisture and waterlogged soil conditions.Tillage may or may not be necessary for a dryland seedling, depending on soil conditions, what weeds are present, and what tillage equipment is available to you. Plowing or ripping to prepare a seedbed is common for most field and vegetable crops but rare for dryland seedling because the economic returns normally do not justify the cost of intensive tillage. In addition, the soil in many dryland pasture sites is too rocky or too shallow to allow any type of deep tillage. Disking or harrowing will usually suffice. This sort of less-intensive tillage serves to loosen the soil enough to let the planter place the seed at the proper depth and cover it with soil. Disking or harrowing also help control weeds that may have emerged before the time of planting. The biggest disadvantage of tillage involves soil moisture—especially for late winter to spring seedlings. Soils at this time of year are often too wet to allow any type of tillage operation. If you feel it is necessary to till before you plant, you have to delay your planting date until the soil has dried enough to allow tillage. This may delay planting beyond the most desirable period and soil moisture may become too scarce when the grasses are trying to get established. In addition, when you till a field it loses much of its soil moisture through evaporation. That means the crop will require rainfall after seedling just to allow the seeds to germinate and to settle the seedbed. One way to minimize soil moisture losses during spring tillage and seedling is to work one day at a time, tilling only the amount of land you can plant that same day. When you prepare a seedbed and plant it on the same day, you can plant the seeds directly into the soil moisture that tillage has brought to the surface. This strategy does have disadvantages, though: you have to pack the soil immediately after tillage in order to achieve a firm seedbed, and there is the hassle associated with switching every day between tillage and seedling activities. A firm seed bed is important: it keeps the seed from being planted too deep and provides good seed-to-soil contact, so if the seed drill is not equipped with press wheels you will want to use a cultipacker behind the drill. Extensive leveling is not usually necessary in dryland seedlings simply because the field will not be irrigated and problems with puddling or dry spots are not likely.