Laserfiche WebLink
<br />Demonstration of Irrigation Technology <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 (TDS) near <br />Pueblo to over 4.000 ppm near the Colorado-Kansas border. Even though TDS in the river is near the 300 <br />ppm level near Pueblo. some irrigation wells in the area have TDS readings as high as 2600 ppm due to <br />natural leaching from saline formations, such as the Greenhorn formation. and due to the salts leached into <br />the ground water aquifer by irrigation. As a result, salinity levels on cropland near the river and on <br />croplands being irrigated with these waters are higher than desirable. <br /> <br />Two basic processes responsible for the high salinity levels are salt pickup and salt concentration. Salt <br />pickup occurs from water flowing over saline and sedimentary materials, from erosion of saline soils, from <br />deep percolation through saline soils and from groundwater flow through saline sedimentary deposits. <br />Irrigated agriculture causes much of the salt pickup by irrigation water flowing over and percolating through <br />salty soils. <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." 1 Evaporation from <br />reservoirs, canals. high water table areas and from cropland receiving excessive amounts of irrigation water <br />or poorly timed irrigations are important consumptive uses as well as evapotranspiration by crops and from <br />weeds and phreatophytes in waste water areas. Municipal and industrial activities also contribute to the <br />consumptive use of these waters. <br /> <br />Crop yields on large acreages are being reduced as a result of high salinity levels. As a result, there is a <br />need to blend improved yielding capabilities and crop types, economic returns, irrigation practices and water <br />quality concerns into a complete management package that can be put into use by agricultural producers. <br /> <br />New, rapid salinity mapping technology will be demonstrated using equipment recently developed by Dr. <br />James Rhoades and his staff at the USDA-ARS Salinity Laboratory of Riverside, California. Two mobile <br />units will be demonstrated. One unit will use a tractor-mounted four-electrode sensor. also called a wenner- <br />array, that measures and logs soil electrical conductivity "on-the-go" while in the soiL. The other mobile <br />unit, an asSAuLT vehicle, is mounted on a high clearance tractor and measures salinity with a sensor above <br />the soil which produces an electromagnetic field that penetrates the soil causing an electrical current flow <br />within the soil profile. The current flow is proportional to the salinity of the soil. This type salinity <br />mapping will help spot field salinity problems before significant crop damage occurs. <br /> <br />Miles, Donald L. "Salinity in the Arkansas Valley of Colorado", May, 1977. Report of <br />Background Information for Educational Program Conducted by the Cooperative Extension <br />Service Colorado State University in Cooperation with the United States Environmental <br />Protection Agency Region VII, Denver. Colorado. <br /> <br />6 <br />