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<br />i <br /> <br />Demonstration of Best Management Practices (BMPs) <br />to Improve Crop Yields, Returns and Water Quality in the <br />Arkansas River Valley of Colorado <br /> <br />I. Summary <br /> <br />The Arkansas River in southeast Colorado is one of the most saline rivers in the United States. The average <br />salinity levels of the canal systems along the river increase from 300 ppm total dissolved solids (IDS) near <br />Pueblo to over 4,000 ppm between Lamar and the Colorado-Kansas border.(Ref. 1) In fact, more than 200,000 <br />acres along the river are irrigated with Class C4 water, the highest classification for salinity hazard. This <br />classification of water has been considered to be too high to be suitable for optimum crop production, however, <br />this water has been used for irrigation in the Arkansas River Basin since the late 1800's. Still, crop yields and <br />returns could be increased if the water quality was improved. Ground water quality in the eastern reaches of <br />the river are also higher than desirable for optimum crop production. <br /> <br />Two basic processes responsible for the high salinity levels are salt pickup and salt concentration. Salt pickup <br />occurs from water flowing over saline and sedimentary materials, from erosion of saline soils, from deep <br />percolation through saline soils and from groundwater flow through saline sedimentary deposits. Irrigated <br />agriculture causes much of the salt pickup by irrigation water flowing over and percolating through salty soils. <br />Shallow water tables and/or perched water tables have, in recent years, been responsible for cultivated land loss <br />or severely reduced crop yields. This shallow water increased the concentration of salts on or near the land <br />surface due to capillary action. <br /> <br />Salt concentration is significantly increased by consumptive use due to human activities. "Consumptive use <br />alone causes a seven-fold increase in the salt concentration in the Arkansas River. "(Ref. 2) Evaporation from <br />reservoirs, canals, high water table areas and from cropland receiving excessive amounts of irrigation water or <br />poorly timed irrigations are important consumptive uses as well as evapotranspiration by crops and from weeds <br />and phreatophytes in waste water areas. Municipal and industrial activities also contribute to the consumptive <br />use of these waters. <br /> <br />Crop yields on large acreage are being reduced, and in some areas, land is being lost for crop production because <br />of high salinity levels. As a result, there is a need to blend improved yielding capabilities and crop types, <br />economic returns, irrigation practices and water quality concerns into a complete management package that can <br />be put into use by agricultural producers. <br /> <br />This proposed project will demonstrate several best management practices (B.MPs) and the economic benefits <br />of this technology to encourage irrigators to use more effective water management. Low energy precision <br />application (LEP A) through center pivot systems will use drag hoses to apply the water on the ground thus <br />eliminating direct application of the saline river or ground water on the plants. <br /> <br />Surge furrow irrigation through gated pipe with the use of computerized, solar powered surge valves is <br />technology that has not been used in the area. Surge irrigation has improved crop yields while reducing <br />irrigation amounts, runoff and deep percolation. Surge irrigation also improves uniformity of application and <br />reduces soil loss due to erosion. <br /> <br />2 <br />