The Nebraska Sandhills is well known as extensive native grasslands, but the abundance of groundwater in the underlying aquifer and development of center pivot irrigation systems led to interest in the potential for crop production in the Sandhills. The expansion of center pivot use was substantial during the 1960s and 1970s and included irrigation development in the Sandhills. Currently, there are about 331,000 acres that are irrigated within the geographic area of the Sandhills. Whereas every Sandhills county has at least some irrigated acres, most of these acres are in the peripheral areas of the Sandhills, where land is more level, and the soils are somewhat less erosive. This includes significant portions of Holt, Wheeler, Brown, Rock, and Antelope Counties. Center pivot irrigation also can be found in scattered locations within interior Sandhills counties, such as Grant, Hooker, Thomas, Blaine, Arthur, and McPherson, with anywhere from two thousand to thirteen thousand irrigated acres.
In the 1970s, faculty from the University of Nebraska–Lincoln West Central Research and Extension Center in North Platte conducted research at a facility called the Sandhills Agricultural Laboratory, located near Tryon. This research focused on several aspects of corn and grain sorghum production, including irrigation and nutrient management, variety testing, and cropping systems for sandy soils. Another important area of research at this facility concerned irrigated perennial grasses and provided a basis for recommendations pertaining to selection of species and variety, fertilizer, irrigation, and grazing management.
Whereas corn and soybeans are the primary crops grown on the more contiguous irrigated acres of the eastern or peripheral Sandhills areas, alfalfa, perennial cool-season grasses, and annual forages are more common on the scattered center pivot acres located elsewhere within the Sandhills. These scattered center pivot acres can be a valuable resource for forage production, particularly if a ranch does not have any, or limited, subirrigated meadow acres. Additionally, the irrigated forage production provides a means to reduce some of the negative impacts associated with drought.
With annual forage production under irrigation, a double-cropping approach is typically used. This often includes seeding a cool-season species, such as rye or triticale, in early fall. The following spring (May or early June) that crop can be grazed or harvested for hay. Immediately following that harvest, a warm-season annual species, such as Sudan grass, forage sorghum, sorghum–Sudan grass hybrids, pearl millet, or foxtail millet is planted. This warm-season forage crop is grazed or harvested in mid- to late summer. The sequence is repeated, with the planting of the cool-season annual again in the fall. Instead of the winter-hardy rye or triticale, spring-planted oats can be another cool-season option. Although the oat growing period is typically not finished until later June, there is still adequate time for growing a warm-season annual forage crop. Total production for both the cool- and warm-season forage crops can range from seven to ten tons per acre.
Alfalfa or cool-season perennial grass production on irrigated acres is another viable option that can benefit a ranching operation. Alfalfa alone, or as the dominant part in a mixture with grass, will provide a high-protein hay source. The use of introduced cool-season perennial grasses is generally favored over warm-season grasses (e.g., big bluestem, switchgrass, Indian grass), because of their greater response to irrigation, fertilizer, and longer growing season potential. A mixture of several species is most often used in these irrigated stands. There are numerous species available, but mixtures that include orchard grass, smooth bromegrass, meadow bromegrass, creeping foxtail, or intermediate wheatgrasses have been found to be well adapted for use on sandy soils and in the Sandhills climate. Adding a legume, such as alfalfa or clover, to the mixture is a common practice.
Similar to a subirrigated meadow, many producers like the flexibility of irrigated cool-season grasses, where they have the option of either grazing or haying or using a combination of haying and grazing on that forage resource. Whereas subirrigated meadows are generally hayed once in midsummer and have some regrowth for fall or winter grazing, irrigated cool-season grasses can be harvested anywhere from two to four times depending on the fertilizer and irrigation management. The cool-season grasses complement the warm-season dominated native Sandhills range, allowing grazing to take place earlier in the spring before native range is ready. There are several grazing and haying combination strategies that can be used, including spring grazing, a summer haying, and then grazing again in fall; or two or three hay harvests and then fall grazing. When strictly hayed, production potential from the irrigated grasses might range from four to seven tons per acre totaled over multiple harvests. When strictly grazed, carrying capacity may be in the range of five to eight animal unit months (AUM) per acre. Management should include some form of rotational grazing that allows for multiple grazing cycles, with the proper time periods for grazing and grass regrowth.