Progress 07/01/02 to 06/30/06
Outputs
This project uses various methods to attempt to diagnose and solve irrigation-induced salinity, waterlogging, and pollutant loading problems in the lower Arkansas River Valley in Colorado. High water tables are a factor in the region's salinity problems. Thousands of measurements of water table depth have been taken at wells around the study area. Water table depth has been found to vary greatly with the amount of precipitation and irrigation water available in the area. Irrigation has also been investigated as a factor in the salinity problem. Hundreds of irrigation events have been monitored to determine the amount of water applied to a given field, the amount of runoff, and the amount of deep percolation. Soil salinity has been examined. Soil samples from the area were collected an analyzed, and a correlation between soil salinity measurements from Electro Magnetic (EM) readings and laboratory ECe measurements was developed, allowing for a significant reduction in
the amount of time it takes to determine soil salinity in a field. Soil properties, including texture and density have been analyzed, and the local soil survey maps were digitized in preparation for updating. Several models of different scales, including the basin scale, have been developed to investigate the effects of salinity and to examine the expected impact of various improvement strategies including: increased irrigation efficiency, altered pumping rates, canal lining to reduce seepage, subsurface drainage, and combinations of these alternatives. The models predict the impacts on water table depth, water table salinity, soil salinity, crop yields, return flow and salt loads to the river, and upflux from the shallow water table to nonbeneficial consumptive use. The basin scale model integrates artificial neural networks for estimating return flows to the river, based upon regional-scale model results, into the MODSIM-Q network model for routing flows and salt loads along the
river. Finally, an economic model of crop production for existing acreage allocations in the Arkansas River Valley is in development. The model shows how changes in salt levels that are external to the farm influence on-farm profits, production levels, and water applications. Mathematical simulations of agricultural production indicate that saline conditions cost producers signficantly. More dynamic responses by growers may help or hurt the farmer's bottom line. Changes in irrigation technology due to saline conditions are of particular concern, since parallel econometric results indicate a positive and significant effect on the adoption of more advanced sprinkler irrigation systems when irrigators perceive soil salinity as an on-farm problem.
Impacts
Solution alternatives considered show promise both for boosting agricultural productivity on the land and enhancing the environmental health of the river. Results from the study suggest that strategies to reduce recharge to the water table by improving irrigation efficiency and reducing canal seepage would (a) lower the saline high water table leading to lower soil salinity and increased crop yields, (b) significantly reduce loading of salts and other pollutants to the river, and (c) markedly reduce nonbeneficial consumptive use under fallow land. As the results of this study are conveyed to farmers and land managers at public meetings and through demonstrations and publications, the stakeholders can make well-informed decisions about the adoption of techniques and technology while keeping in mind their economic bottom line.
Publications
- Gates, T. K., Burkhalter, J. P., Labadie, J. W., Valliant, J. C., and Broner, I. 2002. "Monitoring and modeling flow and salt transport in a salinity-threatened irrigated valley". Journal of Irrigation and Drainage Engineering, ASCE, 128(2): 87-99.
- Huber, D., G. Butters, and M.E. Stromberger. 2003. Short-term Effects of Poor Water Quality on Hydraulic Conductivity. In Annual meeting abstracts [CD-ROM]. ASA, CSSA, and SSSA, Madison, WI.
- Burkhalter, J. P., and Gates, T. K. 2005. "Agroecological impacts from salinization and waterlogging in an irrigated river valley". Journal of Irrigation and Drainage Engineering, ASCE, 131(2): 197 - 209.
- Burkhalter, J. P., and Gates, T. K. 2006. "Evaluating regional solutions to salinization and waterlogging in an irrigated river valley." Journal of Irrigation and Drainage Engineering, ASCE, 132(1): 21-30.
- Wittler, J. M., Cardon, G. E., Gates, T. K., Cooper, C. A., and Sutherland, P. L. 2006. "Calibration of electromagnetic induction for regional assessment of soil water salinity in an irrigated valley". Journal of Irrigation and Drainage Engineering, ASCE, 132(5): 436-444.
- Garcia, L.A., Foged, N., and Cardon, G. (2006) "A GIS-Based Model to Estimate Relative Reduction in Crop Yield Due to Salinity and Waterlogging: Philosophy and Development." ASCE Journal of Irrigation and Drainage Engineering, 132(6) 553-563.
- Gates, T.K, L.A. Garcia, and J.W. Labadie (2006). "Toward Optimal Water Management in Colorado"s Lower Arkansas River Valley: Monitoring and Modeling to Enhance Agriculture & Environment." Colorado Agricultural Experiment Station, Technical Report TR-6-10.
- BERRADA, A., HALVORSON, A.D., BARTOLO, M., VALLIANT, J. (2006). "The effect of subsurface drip and furrow irrigation on the movement of salts and nitrate in the root zone." Irrigation Associations Exposition and Technical Conference Proceedings. P. 1-13.
- HALVORSON, A.D., BARTOLO, M., REULE, C.A., BERRADA, A. (2006). "Onion Response to nitrogen fertilization under drip and furrow irrigation." Proceedings National Allium Research Conference. December 7-8, 2006, College Station, TX p. 73-78.
- HALVORSON, A.D., BARTOLO, M., REULE, C.A., BERRADA, A. (2006). "Onion response to nitrogen fertilization under drip and furrow irrigation." Proceedings of Great Plains Soil Fertility Conference. Denver, CO, March 7-8, 2006. Kansas State University, Manhattan, Potash and Phosphate Institute. Brookings, SD. 11:7-12.
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Progress 01/01/03 to 12/31/03
Outputs
This project is comprised of several subprojects that attempt to diagnose and solve irrigation-induced salinity, waterlogging, and pollutant loading problems in the lower Arkansas River Valley in Colorado. One of the subprojects consists of measuring water table depth and salinity in the two major river reaches in the valley and using the information to model the system and evaluate possible solutions. Work has continued in calibrating, refining, and applying a regional-scale flow and salt transport model for the upstream study region near La Junta. The model has been used to examine the expected impact of several improvement strategies: increased irrigation efficiency, altered pumping rates, canal lining to reduce seepage, subsurface drainage, and combinations of these alternatives. The model predicts impacts on water table depth, water table salinity, soil salinity, crop yields, return flow and salt loads to the river, and upflux from the shallow water table to
nonbeneficial consumptive use. A regional-scale steady-state flow and salt transport model currently is being developed and calibrated toward allowing similar investigations in the study region near Lamar. Major progress also has been made in developing a basin-scale model of the Lower Arkansas River. The model integrates artificial neural networks for estimating return flows to the river, based upon regional-scale model results, into the MODSIM-Q network model for routing flows and salt loads along the river. A second subproject involves developing a correlation between soil salinity measurements from Electro Magnetic (EM) readings and Laboratory ECe measurements. All lab analysis for ECe has now been completed for the upstream reach (years 1999 through 2003) and downstream reach (years 2002 and 2003). Soil texture is underway on remaining samples from the 1999 upstream study sites. In 2003, sampling for soil bulk density was undertaken on a large scale. Triplicate undisturbed soil
cores using a hydraulic insertion probe were collected from approximately 40 upstream sites. Bulk density data will allow expression of water content on a relative saturation basis, thereby normalizing water content information in correlation analysis with field salinity probe data. Complete correlation analysis is expected to be completed in 2004. Once calibrated, the EM probe will offer a reliable method of monitoring the management of soil salinity throughout this important agricultural region. Another subproject deals with the development of an economic model of crop production for existing acreage allocations in the Arkansas River Valley. Based on mathematical simulation models of agricultural production in the Arkansas River Basin, it appears that saline conditions cost producers signficantly in lost profits. More dynamic responses by growers may increase or decrease these potential gains. Changes in irrigation technology due to saline conditions are of particular concern, since
parallel econometric results indicate a positive and significant effect on the adoption of more advanced sprinkler irrigation systems when irrigators perceive soil salinity as an on-farm problem.
Impacts
The calibration that is underway for the EM probe will offer a reliable method of monitoring the management of soil salinity throughout this important agricultural region in a much faster and economical way. Based on the mathematical simulation models of agricultural production in the Arkansas River Basin conducted as part of this project, it appears that saline conditions cost producers approximately $94/acre in lost profits. However, these results are conditioned upon existing cropping patterns and irrigation systems.
Publications
- Cardon G.E. 2003. Salinity Issues in Colorado. In: Berrada, A. and T. Houten (eds), Proceedings of the Third Annual Four Corners Irrigation Workshop. Colorado Agric. Exp. Station, Limited Technical Bulletin LTB03-1. pp 27-32.
- Wittler, J, C. Cooper and G.E. Cardon. 2003. Calibration of Electromagnetic Salinity Probes in an Irrigated, Gypsum-Dominated System. Poster Presentation. American Society of Agronomy annual meeting, Nov 2-6, 2003, Denver, CO. Agron. Abstracts. ASA, Madison, WI.
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Progress 01/01/02 to 12/31/02
Outputs
This project is comprised of several subprojects that attempt to diagnose and solve irrigation-induced salinity, waterlogging, and pollutant loading problems in the lower Arkansas River Valley in Colorado. One of the subprojects consists of measuring water table depth and salinity in the two major river reaches in the valley and using the information to model the system and evaluate possible solutions. Over the 2002 irrigation season, the average measured water table depth in the river reach between Manzanola and La Junta was about 2.80 m, an average increase of about 1 m over measured depths in 2001. The average measured water table salinity over the season was about 3.17 dS/m (2800 mg/L) in 2002, an average decrease of 0.46 dS/m (410 mg/L) compared to 2001. Both of these values show significant improvements and most of the improvement is probably because of the drought and the reduction in irrigation flows. In the river reach between Lamar and Holly, estimates of
measured water table depth and salinity were 3.05 m and 4.86 dS/m (4300 mg/L). A second subproject involves developing a correlation between soil salinity measurements from Electro Magnetic (EM) readings and Laboratory ECe measurements. The EM readings are much faster and if a correlation can be developed this would help significantly reduce the time it takes to determine the soil salinity for a field. Preliminary correlations between lab ECe and field EM readings have been developed and the preliminary results show strong correlations. Best agreement was found with a quadratic formulation (vertical orientation, r-square=0.76; horizontal orientation, r-square=0.75). Measuring water quality effects in salinized soils is the third subproject. An experimental setup has been developed to obtain information on the salinity-water quality interactions on hydraulic properties of Arkansas Valley soils (using a continuous flow method developed at Colorado State University). The experiment has
been set up, and the hydraulic properties of 16 samples have been determined. A fourth subproject deals with the development of an economic model of crop production for existing acreage allocations in the Arkansas River Valley. Currently a working static model of the basin's agricultural production as a function of ambient salt levels has been developed. This model shows how changes in salt levels that are external to the farm influence on-farm profits, production levels, and water applications. The fifth subproject deals with the digitizing a portion of the Soil Survey maps of the area. A procedure to do this has been developed, and about 15% of the digitizing has been completed.
Impacts
Solution alternatives considered thus far show promise both for boosting agricultural productivity on the land and enhancing the environmental health of the river. Results from the upstream study subregion suggest that strategies to reduce recharge to the water table by improving irrigation efficiency and reducing canal seepage would (a) lower the saline high water table leading to lower soil salinity and increased crop yields, (b) significantly reduce loading of salts and other pollutants to the river, and (c) markedly reduce nonbeneficial consumptive use under fallow land. This proposition will be verified and refined by data-calibrated subregional and basin-scale modeling. The relationships, thus far, are quite different from those previously established for the EM method in California and Australia and indicate the need for localized calibration. Drought conditions in Colorado for 2002 were the worst in recorded history, resulting in little irrigation water and
very dry soils throughout the year. The influence of moisture, compounded by the sandier textures of soils in the downstream reach, will continue to be investigated in 2003. The preliminary results hold promise of an effective, reliable correlation between standard labor-and time-consuming laboratory salinity analysis, and the rapid field EM methods. Once calibrated, the EM probe will offer a reliable method of monitoring the management of soil salinity throughout this important agricultural region where estimates of crop yield reduction due to salinity average 10 to 30%
Publications
- No publications reported this period
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