Laserfiche WebLink
<br />, <br /> <br />~ <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />and perhaps more often in the summer months. <br /> <br />The key to an improved and sustained CoAgMet system is the continued strong collaboration among the CSU <br />Experiment Station, Cooperative Extension, commodity groups, United States Department of Agriculture (USDA) <br />Agricultural Research Service (ARS) and Natural Resources Conservation Service (NRCS) personnel who have <br />built and operated the system and the addition of on the ground local DWR support. Critical to this is annual base <br />funding for one full-time position and a part time student technician accountable for the full operation of the <br />network. <br /> <br />III. irrieation Manaeement Studv <br />Conduct studies in the Arkansas River Valley to detennine adjustments for irrigation management and salinity <br />effects that should be made to predictions of evapotranspiration using the Penman-Monteith method. Estimated cost <br />of $220,000 over the three year period July 1, 2004 - June 30, 2007. <br /> <br />In order to use the Penman-Monteith method to predict ET, crop coefficients for the various crops grown <br />specifically in the Arkansas River Valley must be determined. Colorado's experts have testified that the predictions <br />of ET made by the Pemuan-Monteith method need to be adjusted to account for the less than ideal conditions in <br />most agricultural settings when compared with the ET detennined at an agricultural experiment station. Since the <br />required adjustments have never been determined for agricultural settings in the Lower Arkansas River Basin, they <br />can only be obtained through the conduct of studies in the Arkansas River valley. Colorado's experts proposed the <br />use of an irrigation management factor and a salinity adjustment to modify the results obtained using the Penman- <br />Monteith method with accurately detennined crop coefficients. Although the Special Master found that under some <br />conditions, adjustments are made to reflect local conditions, he also found that in this case, a good deal more needs <br />to be known about farm conditions in Colorado before an irrigation management adjustment should be considered. <br />The Special Master also noted that currently there are no standard publications showing a direct relationship <br />between salinity and ET. The Special Master fmally concluded that Colorado's recommended adjustments to the <br />results of the Penman-Monteith method were not sufficiently supported. He concluded his findings with the <br />statement "This is not to say that the Kansas values, as calculated with the Penman-Monteith equation and crop <br />coefficients can never be changed. As more information is developed on conditions in the Arkansas River Valley, <br />adjustments made in accordance with recognized professional procedures may be appropriate," <br /> <br />The studies are expected to take from 3 to 5 years, with the equipment, transportation, lodging and personnel costs <br />shown below in the first year and the transportation, lodging and personnel costs for the next 2 years. A number of <br />fields in an area around Rocky Ford and an area downstream of Lamar will be selected. These two areas coincide <br />with the study regions where Colorado State University (CSU) has been conducting intensive field-scale and <br />regional-scale studies. The fields will be selected based primarily on the type of irrigation as well as the source of <br />water (canals and wells). Current CSU research activities will be re-organized such that the analysis of the data and <br />laboratory work associated with the proposed project will be covered under on-going field scale activities of salinity <br />and waterlogging projects funded by the Colorado Agricultural Experiment Station. Cost estimates were provided by <br />Prof Tim Gates of CSU based on his on-going salinity and waterlogging projects. <br /> <br />For flood irrigated fields, three irrigation events will be monitored. Flumes and automatic recorders will be used to <br />estimate the amount of water applied, the amount of surface runoff, the amount stored for crop consumptive use, and <br />the amount percolating downward to recharge the shallow water table. Fields under sprinkler systems will be <br />selected so that they have flow meters to facilitate estimation of the volume of water applied during each irrigation. <br />For the drip systems, the volume applied during the whole season will be used. Detailed irrigation studies and soil- <br />moisture monitoring are expected to provide enough data to allow reliable estimates of seasonal crop water use on <br />each field. <br /> <br />For the selected fields, where irrigation monitoring is taking place, soil salinity maps will be generated in the early <br />and late part of the season using EM-38 and handheld GPS units. Areas of high, medium and low salinity will be <br />identified in each field. From these areas plants will be collected at least three times during the season and weighted <br />to determine the amount of biomass for each area and to estimate the impact of salinity on plant development. At <br />the end of the season, crop yield from hand-harvested 3 ft x 3 ft areas will be collected (and the location of these <br />plots recorded using a handheld GPS unit) and used to estimate the spatial distribution and total yield for the whole <br />field. <br /> <br />.1 <br />