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• annual, bi-annual and noxious weeds. After consulting, in the field, with Harry Ranney, <br />Colorado Dept. of Minerals and Geology, it was determined that two pastures with reasonable <br />levels of management would be selected for sampling. One pasture was owned by Morgan and <br />the other by Benson. Both had been irrigated in the 1999 season and both had little to no <br />grazing influence. Results of cover, production and woody stem density were based on these <br />two pastures. <br />Perennial grasses dominated the irrigated pasture type with vegetative cover of 44.5 percent, <br />while perennial forbs accounted for nearly all of the remaining vegetative cover (33.3 percent). <br />Total annual production for the type was estimated at 4,153 pounds/acre. Woody stem density <br />was zero in this type. A total of 64 species were found to occur in the type, with 21 of those <br />species encountered in the cover sampling. Only 15 of these species had relative cover values <br />of 1 percent or greater. Of these 15 species, 8 were graminoids and 7 were forbs. <br />Irrigated pasture occurs on soil map units 98A, 96C, 98D, 98E and 98F and 98G. Soil ranges <br />from deep to shallow. Moderately deep to deep irrigated pastures have a potential to become <br />• irrigated haylands. Some operators have chosen to let hayland areas degrade over time so <br />that the current use is irrigated pasture. Pastures on shallow soil have a lower production value <br />and are irrigated solely due to the fact that they are down slope from an irrigation ditch. <br />The 1987 conclusions are restated here as they have the same application and results as <br />those found in 1999. The general stocking rate for the irrigated pasture is approximately 1.2 <br />AUM's/acre at a 70 percent utilization rate. Since the production on these pastures can be <br />sustained by irrigation, this stocking rate should apply during the majority of the growing <br />season. Ideally, the forage should achieve a 4-5 inch height in the spring and between pasture <br />recovery periods before grazing with allowance fora 4-5 inch stubble height of vegetation <br />remaining at the end of the growing season (SCS 1985). Observations during 1999 indicate <br />that the trend is to graze early, continuously during the growing season, and late for a number <br />of the operators. <br />Many factors contribute to the composition, utility and appearance of the irrigated pasture type. <br />Soils vary from deep sandy loams to shallow sandy loams with a few rock outcrops (see <br />• (REVISED 9/99) 2.04.10 - 58 <br />