Research, Extension and Outreach Projects
Project title and duration: Irrigation Strategies for Erosion Reduction in the Salton Sea Watershed (2000-2003)
Collaborators: K. M. Bali, PI and Project Leader. Juan Guerrero, Livestock Advisor, Imperial County, Jose Aguiar, UCCE-Indio.
Grant support: California State Water Resources Control Board $113,605
US Bureau of Reclamation (provided surge value, irrigation equipment, data loggers, and flumes. Total USBR support: approximately $12,000)
Background, rational, and objectives: Alfalfa acreages account for almost 35% of the 500,000 acres of irrigated land in the Imperial Valley. Alfalfa annual water usages in Imperial Valley exceed one million acre-feet with an average consumptive use of 6.5 ac-ft/ac. Lettuce is the dominant vegetable crop in the Valley. Approximately 35% of the delivered irrigation water in the Valley becomes drainage water (surface & subsurface). Imperial Valley drains and rivers are listed on the State’s 303(d) list. Sediment/silt TMDL has already been developed to reduce sediment load in Imperial Valley drains and rivers. The goal is to achieve 50% reduction in sediment load in drainage water (current average sediment load in drainage water is approximately 400 mg/L). The objectives of this project are: 1) demonstrate the use of management practices (surge & polyacrylamide) to conserve water and reduce sediment load in surface runoff water, 2) develop BMPs for these practices, and 3) conduct educational and outreach efforts to promote practices that conserve water and improve water quality.
Results: The application of PAM through irrigation water resulted in significant improvements in the quality of surface runoff water. Silt loads in surface runoff water were reduced by as much as 90% as compared to normal irrigation practices. Implementation of surge irrigation on lettuce resulted in significant improvements in water quality and no significant impact on yield. In addition to the reduction in silt loads, both management practices reduced the concentration of phosphorous in surface runoff water. Best management practices for implementation of the above practices were developed. The total costs of implementing the above practices ranged from approximately $5 to $25 per acre.
Project title and duration: Irrigation Management Reduces Tailwater (2000-2003)
Collaborators: K. M. Bali, Co-PI and Juan Guerrero, PI, Livestock Advisor, Imperial County
Grant support: California State Water Resources Control Board $264,902
US Bureau of Reclamation (provided irrigation equipment, data loggers, and flumes. Total USBR support: approximately $8,000)
Background, rational, and objectives: Alfalfa acreages account for almost 35% of the 500,000 acres of irrigated land in the Imperial Valley. Alfalfa annual water usages in Imperial Valley exceed one million acre-feet with an average consumptive use of 6.5 ac-ft/ac. Approximately 35% of the delivered irrigation water in the Valley becomes drainage water (surface & subsurface). Imperial Valley drains and rivers are listed on the State’s 303(d) list. Sediment/silt TMDL has already been developed to reduce sediment load in Imperial Valley drains and rivers . The goal is to achieve 50% reduction in sediment load in drainage water. The objectives of this project are: 1) demonstrate the use of runoff reduction method to conserve water and reduce sediment load in surface runoff water, 2) conduct educational and outreach efforts to promote practices that conserve water and improve water quality.
Results: We found that the runoff reduction method is effective in reducing silt load in runoff water and effective in conserving water. The silt load in surface runoff water was reduced by approximately 50% as compared to normal practices. Water savings were significant, 19% in water saving as compared to normal practices. Alfalfa yield and soil salinity were not impacted by our method.
Project title and duration:Optimization of Water and N Application Efficiency for Surface Irrigated Production Systems (2000-2003)
Collaborators: K. M. Bali, Co-PI and Project Leader in CA. Sanchez, Zerrihun, Warrick, all from The University of Arizona, Tucson.
Grant support: USDA-National Research Initiative program $227,000
Background, rational, and objectives: The low deserts soils are commonly used for the production of high value vegetable crops. Water scarcity in the arid southwestern United States is a major impetus for improving water use efficiency in agriculture. Nitrate contamination of surface and groundwater is often associated with excessive irrigation and fertigation practices. We developed new design and management approaches and guidelines for N-fertigation system in surface irrigation settings through field experiments and modeling simulation studies. Our objective was to conduct field experiments to develop database for the calibration and validation of surface hydraulics and chemical transport models. Such models can be used to develop improved management guidelines for the N-fertigation practices in the desert southwest.
Results: We collected several sets of data that we used to simulate N-fertigation practices efficiency under different conditions (varying furrow flow rates, N- concentration in irrigation water, and soil infiltration characteristics). Our growers are under continuous pressure to save water and reduce the amount of nitrogen and fertilizers in surface and subsurface drainage. Results from our work will develop guidelines for new fertigation practices under varying soil and irrigation management practices. We expect that our recommendations will be used by growers to improve fertilizer use efficiency and reduce the impact of nonpoint source pollution on the Salton Sea watershed. Our educational materials can be used to meet the expected Salton Sea Nutrient TMDL regulations.
Project title and duration: Extension of CIMIS to Baja California to improve irrigation efficiency (2001-2002)
Collaborators: Snyder and Bali, UCD & UCCE-Imperial County
Ruiz & Orozco, University of Baja California and State of Baja California, Mexicali, Mexico
Eching, Orang, California department of water resources, Sacramento.
Grant support: UCMEXUS $26,466
Background, rational, and objectives: The University of California (UC) and the California Department of Water Resources (CDWR) developed the California Irrigation Management Information System (CIMIS) to provide badly needed information on reference evapotranspiration (ETo) rates to California growers. The original idea was to improve irrigation efficiency to reduce the demand for water from the developed supply, which reduces the need to build more dams. The ETo information from CIMIS is used in conjunction with crop coefficient (Kc) values to estimate crop evapotranspiration (ETc). The number of weather stations in CIMIS has increase to more than 100 (compare to 43 when CIMIS was started in 1982). Growers in California extensively use evapotranspiration information from CIMIS. Parker et al. (California agriculture,2000) estimated that California growers save approximately $64,700,000 per year in water and energy savings as well as improve production by using CIMIS. Although not included in their paper, the reduction in water applications also reduces fertilizer usage and ground water pollution. In this project, our objective was to expand the CIMIS network by installing two CIMIS weather stations in Baja California, Mexico. Our goal was to provide ETo information, an improved weather data set, and to foster joint teaching and research between UC and the Autonomous University of Baja California.
Results: Two CIMIS weather station were calibrated and installed in the Mexicali Valley. The two new CIMIS stations (#185 UC-Mex and #186 UC-San Luis) were linked to the CIMIS weather stations network and website in January and April, 2002 (http://www.cimis.water.ca.gov/). Educational activities were conducted in the Imperial and Mexicali valleys.
Project title and duration: Agricultural Management Practices for Phosphorus Reduction in the Salton Sea Watershed (2003-2006).
Collaborators: K. M. Bali, PI and Project leader. Herman Meister & Juan Guerrero, UCCE-Imperial; Jose Aguiar, UCCE-Indio; Dan Putnam and Roland Meyer, UCD; Mark Grismer, UCD, Nicole Rothfleisch, Executive Director, Imperial County Farm Bureau; Jason Smith, NRCS, Escondido.
Grant support: California State Water Resources Control Board $241,500
Background, rational and objectives: The Salton Sea exists because of drainage water from agriculture in Imperial and Coachella Valleys as well as flow of agricultural drainage and industrial discharges from Mexico. Agricultural discharges from the Imperial Valley account for almost 85% of the total annual flow of fresh water to the Sea. As the largest inland body of water in California, the Salton Sea provides significant habitat for fish and wildlife. Rising salinity, sediment, nutrients, pesticides, and pollution threaten these habitats. Excessive load of nutrients (mainly phosphorous and nitrogen) and sediment in Imperial Valley drains and rivers have resulted in degraded conditions that impair the designated beneficial uses of the Salton Sea. The Salton Sea Nutrient TMDL Technical Advisory Committee (TAC) and other agencies have identified phosphorous (P) as the primary nutrient creating eutrophic conditions in the Salton Sea. This project will focus on seven cost-effective Best Management Techniques (BMTs) for P load reduction to the Salton Sea. Reduction in the quantity and concentration of P discharged into agricultural drains can be achieved by altering irrigation and fertigation (applying nutrients through irrigation water) management practices.
Results: Preliminary results indicate that P concentration in surface runoff water range from 0.4 to 1.2 mg/L (soluble P). The concentration of P in tile water ranged from 0.05 to 0.3 mg/L. The range of concentrations found in drainage water is approximately two to ten times the P concentration levels that cause eutrophic conditions in the Salton Sea. Significant improvements in water quality are expected as a result of the implementation of these BMTs.
Project title and duration: Imperial Valley Drains Silt TMDL Modeling Studies (2003-2004)
Collaborators: K. M. Bali, Co-PI. Greg Pasternack and Wesley Wallender (UCD professors).
Grant support: California State Water Resources Control Board $99,890
Background, rational and objectives: California Regional water Quality Control Board (Region 7) has been taken monthly sediment load data (drain flow rate and sediment concentration). Sediment load from these monthly data is likely to contain significant errors in estimating sediment loses from agricultural fields in the Valley. Sediment load derived from agricultural return water drainage is highly variable over hours in response to changing flow rate due to the nature of irrigation practices. Because of this natural relationship, a sediment budget based on once-a-month measurements that does not explicitly sample a wide range of loads is likely to contain significant error. As an alternative to expensive, long-term monthly monitoring that leaves farmers uncertain for a long time period while monitoring is on-going, it should be possible to develop a highly accurate sediment budget through continuous monitoring of sediment load and flow rate during irrigation events over 1-3 months, given that fields are irrigated approximately once every 2-6 weeks.
Results: Variation in turbidity and flow rate decreases in frequency from small scale drains to big scale drains implying that different mechanics dominate total suspended sediment (TSS) transport at different scales. The turbidities at small scale (i.e. field scale) are considerably greater than those at middle and big scales, whereas those at the middle scale are not quite different from that at the big scale. This trend indicates that more deposition occurs during the transport of TSS from small scale to middle scale than from middle scale to big scale. A model is being developed to estimate the spatial and temporal variations in sediment loads for various drainsheds in the valley. The model will help both CRWQCB-7 staff and local growers in estimating sediment loads and documenting improvements in water quality in response to various management practices. The model will help both CRWQCB-7 staff and local growers in estimating sediment loads and documenting improvements in water quality in response to various management practices.
Project title and duration: Wheat Reduced Irrigation Studies (2002-2005)
Collaborators: K. M. Bali Co-PI , Lee Jackson ,UCD, and Herman Meister , Imperial County
Grant support: Various donors account and Partial support from Lee Jackson, UCD
US Bureau of Reclamation (provided irrigation equipment, data loggers, and flumes, and technical assistance Total USBR support: approximately $7,000/year)
Background, rational, and objectives: The proposed water transfer agreement between Imperial Irrigation District (IID) and the San Diego County Water Authority (SDCWA) calls for transfer of up to 300,000 acre-feet annually of Imperial Valley-Colorado River water to San Diego. Most of the water available for transfer will have to come from on-farm water conservation practices. Wheat acreages in the Imperial Valley account for 10-20% of the 500,000 acres of irrigated land in the Imperial Valley. Wheat annual water usage in Imperial Valley is about 2.5-3.0 acre-feet/acre. With the continued demand for water in urban areas, it is apparent that traditional water conservation measures such improving irrigation efficiency and using more efficient systems such as pressurized irrigation systems may not yield enough water to meet the expected demand for water in urban areas. The objectives of this project are: 1) determine the potential water savings from reducing the number of irrigations on wheat and 2) evaluate the impact of reduced application of water on wheat yield and quality parameters.
Results: We found that reducing irrigation frequency from five to three irrigations per season saved approximately 25% of the applied water and reduced wheat yield for certain varieties. The average yield of all the varieties in the trial for the normal irrigation was 7,050 lbs/acre, but dropped to 5,960 lbs/ac under the reduced irrigation. The 1,100 pound reduction in yield translates to a net loss of approximately $70 per acre. The varieties that suffered 500 lb or less were selected for further studies in 2003/04 season. Additional work is currently underway (2003/04 wheat season) to evaluate the impact of reducing the irrigation frequency by one and two irrigations on wheat yield and quality.
Project title and duration:Quantitative and Qualitative Assessment of Soil Organic Carbon in Native and Cropland Soils in California (2002-2003)
Collaborators: (PI: Laosheng Wu, Andrew C. Chang, Co-PI, Collaborators: Blake McCullough-Sanden, UCCE, Kern County and K.M. Bali, UCCE, Imperial County)
Grant support: Kearney Foundation $69,989
Background, rational, and objectives: Soil organic carbon (SOC) plays important roles in stabilizing soil aggregates, increasing water-holding capacity of soils, and promoting soil fertility. Organic matter stored in the soils also represents atmospheric carbon dioxide (CO2) that has been sequestered, thus mitigating greenhouse gas emissions and their effects on global warming. The C storage and turnover rates are the determinant factors that will influence the structure and the extent of carbon sequestration of soils. Cultivation practices alter the carbon inputs and outputs in the soils. The changes in the nature of carbon through cultivation may be assessed by comparing the C stocks in soils presently under cultivation with those of the uncultivated native soils. If soils with different durations of cultivation are evaluated, the turn over rates of organic carbon and the evolution of the chemical structures of organic carbon in the soils may be deduced. This investigation determined the dynamic change of carbon storage in native soils and cropland soils that have been cultivated for different length of time.
Results: The labile carbon content and carbon management index were significantly different between native soil and the soil that has been cultivated and irrigated for more than 15 years. The difference indicated that although the total carbon was similar in native and cultivated/irrigated soil, cultivation and irrigation increased the carbon turnover rate. The labile carbon content of the native soil and the soil that has been cultivated for about 10 years was not significantly different. It appears to take about 10-15 years of cultivation and irrigation for the carbon turnover rate of the cultivated soils to exhibit a significant difference. Soil organic carbon plays important roles in stabilizing soil aggregates, increasing water-holding capacity of soils, and promoting soil fertility. Understanding SOC and C storage and turnover rates will help us manage cultural practices in a way to promote healthy soil management practices that can improve fertilizer use efficiency and increase soil water holding capacity.