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<br />Demonstration ofIrrigation Technology <br />to Improve Crop Yields, Returns and Water Quality in the <br />Arkansas River Valley of Colorado <br /> <br />by <br />Jim Valliant <br />Project Coordinator <br />Colorado State University <br />Cooperative Extension <br /> <br />Progress Report <br />to <br />Colorado Water Conservation Board <br />Department of Natural Resources <br />March 1998 <br /> <br />1997 was a very disappointing year because of the failure, once again, to establish either grasses <br />or legumes on Pivot #7. Also, because of the untimely rains, quantity and quality ofthe alfalfa <br />grown under Pivot #8 was much lower than expected. Only the fact that the stand of alfa\fa on <br />Pivot #8 was improved by overseeding in the spring of 1997 was there any real success. <br /> <br />Again as in 1996, different grass mixtures and/or grass-legume mixtures were planted in Pivot #7 <br />as were two different types of sorghum/sudan grass. The different grasses and grass-legume mixes <br />were planted in early spring and irrigated with water from Well #11, which has better water <br />quality than previously applied using Well #13. The Total Dissolved Solids (TDS) in Well #11 <br />was down to 1,200 ppm as compared to the 4,000 ppm when using Well #13. Seedling sprouts <br />were found throughout the field, however; very few of these sprouts emerged above the soil <br />surfuce. The grasses and grass-legume mixtures were sprinkle irrigated to germinate the seed and <br />plans were made to irrigate this area using drag lines extending down from the sprinkler heads to <br />the ground. Applying irrigation water in this manner would have eliminated saline water being <br />applied to the leaf surface, thus, reducing the possibility of increased salinity due to crystalizing of <br />this water on the leaf. Grasses planted include NewHy Wheatgrass and different mixtures of <br />Orchardgrass, Smooth Bromegrass and Intennediate Wheatgrass as well as Birdsfoot Trefoil and <br />Cicer Milkvetch. <br /> <br />The two different types of sorghum/sudangrass planted under Pivot #7 were a standard type and <br />a Brown Mid Rib type. The Brown Mid Rib type has been show to be more palatable because of <br />the reduction in lignin. The Brown Mid Rib appeared to be more susceptible to salinity as the <br />early growth was not as vigorous as the standard, however; excessive amounts of weeds masked <br />any results that would have shown this effect. Early growth ofthe sorghum/sudangrasses was <br />encouraging but stunting ofthe plants started to occur just as the weeds were emerging. The <br />weeds were sprayed aerially as the crop could not be cultivated because of the close row spacing. <br />Unfortunately, the spraying did not give the kill that was anticipated and resulted in weeds <br />continuing to be competitive with the crop. The sorghum/sudangrass was harvested twice during <br />the growing season, but, again, untimely rains severely reduced the quality of the hay. <br />