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• A total of 66 species were found to occur in the type (Peabody Appendix 10-1), with 21 of those <br />species encountered in the cover sampling. Only 12 of these species had relative cover values <br />of 1 percent or greater. Of these 12 species, 8 were graminoids and four were fortis. Though <br />this represents a low level of diversity for native plant communities, irrigated pastures that are in <br />good condition and well managed should have a composition of only a few species (Stewart <br />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 fora 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 early, <br />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 looms to shallow looms 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 lands <br />for irrigated pasture. At the other extreme, are the areas of shallow soils. These lands normally <br />occur as the remnant sagebrush type or as disturbed areas associated with farmsteads or <br />facilities. In these cases, the operator has chosen to apply irrigation water on seeded pasture <br />species even though the site potential is low. In some cases, the sites are so shallo, that tillage <br />and seeding are not feasible and continued application of irrigation water has allowed for <br />volunteering of species normally found in the irrigated pasture type. These shallo, sites have a <br />lower production potential than the deeper sites, but it is much higher than if left in the dry <br />remnant sagebrush state. Within the irrigated pasture type are small localized areas that receive <br />only limited amounts of supplemental irrigation water because of the natural topography or <br />landform. These areas are too small to stratify out from the type. Land leveling or shaping to <br />overcome these problems has not been done to any great extent within the study area. Ground <br />water seeps and boggy areas from irrigation runoff and irrigation recharged ground water <br />• (REVISED 8/15/00) 2.04.10 - 29 <br />