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A total of 66 species were found to occur in the type (Attachment 2.04.10-6, formerly Peabody <br />10-1), with 21 of those species encountered in the cover sampling. Only 12 of these species <br />had relative cover values of 1 percent or greater. Of these 12 species, 8 were graminoids and <br />four were forbs. Though this represents a low level of diversity for native plant communities, <br />irrigated pastures that are in good condition and well managed should have a composition of <br />only a few species (Stewart 1973). <br />The general stocking rate for the irrigated pasture is approximately 1.2 AUM's/acre at a 70 <br />percent utilization rate. Since the production on these pastures can be sustained by irrigation, <br />this stocking rate should apply during the majority of the growing season. Ideally, the forage <br />should achieve a 4-5 inch height in the spring and between pasture recovery periods before <br />grazing with allowance for a 4-5 inch stubble height of vegetation remaining at the end of the <br />growing season (SCS 1985). Observations during 1987 indicate that the trend is to graze <br />early, continuously during the growing season, and late for a number of the operators. <br />Many factors contribute to the composition, utility and appearance of the irrigated pasture type. <br />Soils vary from moderately deep loams to shallow loams and with a number of rock outcrops <br />(see Section 2.04.9, Soils Resource Information). The deeper soils could be placed in hay <br />production, however the various operators' management objectives dictate a use of these <br />lands for irrigated pasture. At the other extreme, are the areas of shallow soils. These lands <br />normally occur as the remnant sagebrush type or as disturbed areas associated with <br />farmsteads or facilities. In these cases, the operator has chosen to apply irrigation water on <br />seeded pasture species even though the site potential is low. In some cases, the sites are so <br />shallow, that tillage and seeding are not feasible and continued application of irrigation water <br />has allowed for volunteering of species normally found in the irrigated pasture type. These <br />shallow, sites have a lower production potential than the deeper sites, but it is much higher <br />than if left in the dry remnant sagebrush state. Within the irrigated pasture type are small <br />localized areas that receive only limited amounts of supplemental irrigation water because of <br />the natural topography or land form. These areas are too small to stratify out from the type. <br />Land leveling or shaping to overcome these problems has not been done to any great extent <br />within the study area. Ground water seeps and boggy areas from irrigation runoff and irrigation <br />recharged ground water systems contribute to areas of higher production or occur as small <br />inclusions of the swale/drainage vegetation type. <br />February 2015 (TR -66) 2.04.10-34 <br />