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United States Department of Agriculture

Agricultural Research Service

Research Project: SALINITY AND TRACE ELEMENTS ASSOCIATED WITH WATER REUSE IN IRRIGATED SYSTEMS: PROCESSES, SAMPLING PROTOCOLS, AND SITE-SPECIFIC MANAGEMENT
2012 Annual Report


1a.Objectives (from AD-416):
Water quality criteria were initially developed to protect irrigated soils from possible adverse soil structural changes (such as reduced infiltration) and avoid reductions in crop yield due to salinity. Increased demands on our limited water resources necessitates that we more accurately determine these criteria since many waters deemed unsuitable can be used under specified conditions. Application of these criteria and application of recycled irrigation drainage water and treated municipal waste water will reduce the margin of error and require that we carefully monitor changes in soil properties, and thus develop improved monitoring protocols and practices. Based on these needs the research project is focused under two objectives: Objective 1: Develop new knowledge and guidelines related to major ion, B, and Mo concentrations for the sustained use of degraded waters including drainage waters and municipal waste waters. Objective 2: Evaluate the use of geophysical and geographic information system technology to monitor spatio-temporal changes of soil properties, salinity, trace elements and N. Both of these objectives are necessary for effective and protective implementation of irrigation with impaired waters. Although the stated objectives can be achieved by pursuing parallel lines of research, they will be combined in development of management practices. The monitoring technology objective is also essential to future field evaluation of the criteria and predictions made relative to objective one.


1b.Approach (from AD-416):
1:The adsorption behavior of Boron (B) and Molybdenum (Mo) will be studied as a function of solution pH, solution anion concentration, electrolyte composition, and competing anion concentration in batch systems on soils chosen to represent a variety of soil orders. The adsorption behavior will be described using a chemical surface complexation model, allowing for development of improved management of degraded waters high in B and Mo. The desorption behavior of both native soil B and recently added B will be characterized in batch systems to determine the extent of desorption hysteresis in the presence and absence of competing ions. If desorption hysteresis is found, mathematical equations will be developed to describe the B desorption process in batch systems. Data will be analyzed, and B movement predicted using initial soil characteristics, ET calculations, and water composition using the UNSATCHEM model. New B transport routines will be developed if needed. Waters of varying composition including salinity, SAR, pH, alkalinity, and Ca/Mg ratio, will be applied to soils in outdoor containers with measurement of the water infiltration rate for both irrigation water and alternate application of rain using a rainfall simulator. The results of these experiments will be incorporated into predicted routines in UNSATCHEM and in guidelines for use of impaired waters. We will evaluate the impact of use of degraded water on soil quality, productivity and forage quality of a marginally productive saline-sodic soil. Characterization of soil spatial variability will utilize ECa measured by electromagnetic induction equipment, where each site is geo-referenced using GPS. 2: Validation of use of ECa-directed sampling to spatially characterize soil properties (salinity, texture, water content) will be made at a drainage water reuse site. ECa measurements will be used to determine 40 site locations from a response surface sampling design algorithm. Additional sites will be randomly selected for a validation data set. Correlating properties will be predicted from spatial regression models and compared to randomly chosen positions where validation sample data have been collected with development of a protocol for model validation of directed sampling techniques. A site in semi-arid CO under no-till will be used to evaluate ECa-delineated zones as a framework for site-specific N management in winter wheat and for field-scale monitoring of soil quality response and identification of soil quality trends. To evaluate site specific management, using ECa zones, 3 years of yield, ECa zone, and N-treatment maps will be compared with geo-referenced soil sample analyses for N-use efficiency and optimal N rates for each ECa zone. A phenomenological model of salinity development will be formulated based on spatial data of potential soil salinization factors (e.g., soil type, poor drainage areas, topography, leaching fraction, depth to groundwater, groundwater quality, etc.) for the Red River Valley basin of North Dakota and Minnesota. The phenomenological model will be used to create an inventory map of salinity for the entire Red River Valley.


3.Progress Report:
This is the final report for project 5310-61000-013-00D which started in 12/2006. This project research is continued in the new project 5310-61000-016-00D. Integrated field scale management systems for use of degraded waters. We measured Selenite adsorption on oxides, clay minerals and 45 soils as a function of pH and successfully modeled the data with the triple layer surface complexation model. We determined that apparent boron adsorption hysteresis on high organic matter soils was actually a deficiency of existing experimental techniques, thus simplifying B modeling. Boron (B) adsorption in the presence of divalent and monovalent cations was similar, thus no need to consider cation composition to predict B transport. We established that most B release in arid land soils is due to desorption rather than mineral dissolution, thus producers need not be concerned about regeneration of B toxicity after leaching. Molybdenum (Mo) is sometimes present in drainage waters at levels toxic to livestock. We studied Mo adsorption on soil as a function of pH, salinity and Mo and competing ion concentration. Adsorption behavior was well described using a chemical surface complexation model. Long-term sustainability of degraded water use was evaluated with ECa-directed sampling of soil quality. Spatio-temporal analysis of the data established that agricultural drainage water can be utilized for irrigation and in some instances reduce salinity and sodicity. Results also showed that in the presence of a shallow water tables the reclaimed soils quickly return to their original state upon terminating irrigation. Integrated advanced information technologies were used to delineate Site-Specific Nitrogen Management Units, establishing optimal N rates for ECa-based management units. Response surface soil sampling design was shown to be more efficient than traditional design based sampling. We utilized satellite imagery to assess soil salinity in 300,000 acres of the Red River Valley in Minnesota. We correlated salinity variability to multi-year enhanced vegetative index, crop history, and land eligible for Conservation Reserve Program, thus providing protocols for mapping soil salinity at the regional scale. We developed a new version of UNSATCHEM with improved routines for B adsorption. We developed the Extract Chem, model to predict composition of a soil extract with changes in water content, We measured B transport in soil columns for 3 arid land soils at two pH values (adsorption is pH dependant). We obtained good predictions of B transport using the UNSATCHEM model, utilizing basic soil properties to predict adsorption, thus avoiding the need to measure individual adsorption-desorption-pH dependence of each soil. We measured infiltration rates for soils treated under combined irrigation-rain applications at different sodium and pH values of irrigation water. We determined that increases in pH reduced infiltration rates and that this effect was magnified with successive wetting and drying cycles. We developed new water suitability criteria for irrigation that account for the impact of rain, pH, wetting and drying cycles, as well as salinity and sodicity.


4.Accomplishments
1. Water quality criteria for irrigation. Using marginal waters and treated wastewaters for irrigation increases the need for accurate water quality criteria. Agricultural Research Service (ARS) scientists in Riverside, California, used results from new field and laboratory experiments to revise earlier water quality criteria, now relating infiltration hazard to pH, as well as SAR (sodium adsorption ratio), and salinity, replacing earlier Food and Agricultural Organization (FAO) criteria that did not consider pH and underestimated the adverse impacts of low SAR on water infiltration. New guidelines related to infiltration hazard are now also provided for environments where rainfall is a contributor to the water budget. Results from this work provide water quality specialists, water planners, regulatory agencies, and producers with the improved ability to evaluate the infiltration hazards associated with the application of irrigation waters based on their chemical composition. The improved guidelines ensure safer use of saline waters for irrigation and thus extend the supply of water resources available for agriculture.

2. Identification of adsorbed boron (B) versus mineral incorporated boron in soils. Boron is a specifically adsorbing anion that can be detrimental to plants at elevated levels. To avoid B toxicity for agricultural crops, there is a need to accurately characterize B pools in soil, because availability of adsorbed boron is greater than boron incorporated in mineral forms. Release of native adsorbed B has been reported to be a significant source of soluble B in arid land soils. Agricultural Research Service scientists in Riverside, California, established that most B release is due to desorption rather than mineral dissolution. Thus producers do not have to be concerned about the regeneration of soluble B and its potential toxicity after leaching to below toxic levels. This research is important for managing and controlling soluble B in regions with high native soil B, such as commonly occur in the arid southwestern U.S.

3. Water reuse can be evaluated with (Electrical Conductivity) ECa-directed sampling. Drainage water reuse offers a means of providing an additional source of irrigation water and concurrently reducing the volume of drainage water disposed in evaporation ponds or surface waters, but nothing is known of its long-term impact and sustainability. The long-term (i.e., 12 years from 1999-2011) impact and sustainability of drainage water reuse on a saline-sodic field in San Joaquin Valley’s west side (WSJV) was evaluated by an ARS researcher at Riverside, California, using a electrical conductivity remote sensing directed soil sampling to measure and monitor spatial changes in soil properties affecting the yield and quality of a forage crop. Results indicated a reduction in salinity, Molybdenum (Mo), Boron (B), and SAR through the top 1.2 m of the soil profile from 1999-2009. The discontinued reuse of drainage water from 2009-2011 caused soil salinity and SAR to build gradually, returning the study site to levels comparable to 1999. The study demonstrated both the viability of using drainage water to reclaim saline-sodic soils but also how quickly reclaimed soils return to their original degraded state once irrigation was terminated. This information is of use to farm managers and advisors managing drainage water for agricultural reuse.

4. Computer model to convert soil solution concentrations to different water contents. In many instances consultants and researchers use a high water dilution extract such as 1:2 or 1:5 soil:water for analysis and diagnosis of salinity problems. Interpretation of these data is complicated as crop salt tolerance data are reported in terms of a saturation extract water content that cannot be easily calculated from the higher water content extract composition often measured. We have developed a new user friendly computer model (Extract Chem) that enables conversion of water composition at one water content to that at another water content. This allows for accurate assessment of soil water salinity and composition, including B concentration. The model is available on our ARS website for download on our FTP site. Users are a mixture of researchers as well as consultants, farm advisors and technical specialists.


Review Publications
Corwin, D.L., Lesch, S.M., Lobell, D.B. 2012. Laboratory and field measurements. In: Wallender, W.W. and Tanji, K.K. (eds.) ASCE Manual and Reports on Engineering Practice No. 71 Agricultural Salinity Assessment and Management. 2nd Edition. ASCE, Reston, VA. p. 295-341.

Lesch, S.M. 2012. Statistical models for the prediction of field scale, spatial salinity patterns from soil conductivity survey data. In: Wallender, W.W. and Tanji, K.K. (eds.) ASCE Manual and Report on Engineering Practice No. 71 Agricultural Salinity Assessment and Management. 2nd Edition. ASCE, Reston, VA. p. 461-482.

Deverel, S.J., Goldberg, S.R., Fujii, R. 2012. Chemistry of trace elements in soils and groundwater. In: Wallender, W.W. and Tanji, K.K., editors. ASCE Manual and Reports on Engineering Practice No. 71. Agricultural Salinity Assessment and Management (2nd Edition). ASCE, Reston, VA. Chapter 4. p. 89-137.

Corwin, D.L., Rhoades, J.D., Simunek, J. 2012. Leaching requirement: Steady-state versus transient models. In: Wallender, W.W. and Tanji, K.K. (eds.) ASCE Manual and Reports on Engineering Practice No. 71 Agricultural Salinity Assessment and Management. 2nd Edition. ASCE, Reston, VA. p. 801-824.

Suarez, D.L. 2012. Irrigation water quality assessments. In: Wallender, W.W. and Tanji, K.K. (eds.) ASCE Manual and Reports on Engineering Practice No. 71 Agricultural Salinity Assessment and Management (2nd Edition). ASCE, Reston, VA. Chapter 11 pp. 343-370.

Suarez, D.L. 2012. Modeling transient rootzone salinity (SWS Model). In : Wallender, W.W. and Tanji, K.K. (eds.) Agricultural Salinity Assessment and Management. ASCE Manual and Reports on Engineering Practice No. 71 (2nd Edition). ASCE, Reston, VA. Chapter 28 pp. 855-897.

Suarez, D.L., Jurinak, J.J. 2012. The chemistry of salt-affected soils and waters. In: Wallender, W.W. and Tanji, K.K. (eds.) ASCE Manual and Reports on Engineering Practice No. 71 Agricultural Salinity Assessment and Management (2nd Edition). ASCE, Reston, VA. Chapter 3 pp. 57-88.

Corwin, D.L. 2012. Field-scale monitoring of the long-term impact and sustainability of drainage water reuse on the west side of California’s San Joaquin Valley. Journal of Environmental Monitoring. 14(6)1576-1596.

Skaggs, T.H., Suarez, D.L., Goldberg, S.R., Shouse, P.J. 2012. Replicated lysimeter measurements of tracer transport in clayey soils: Effects of irrigation water salinity. Agricultural Water Management. 110:84-93.

Ha, W., Suarez, D.L., Lesch, S.M. 2011. Perchlorate uptake in spinach as related to perchlorate, nitrate and chloride concentrations in irrigation water. Journal of Environmental Science and Technology. 45(21):9363-9371.

Suarez, D.L., Wood, J.D., Taber, Jr, P.E. 2012. Adsorption and desorption of B in column studies as related to PH: Results and model predictions. Vadose Zone Journal. 11:DOI:10.2136/vzj2011.0073.

Ayars, J.E., Corwin, D.L., Hoffman, G.J. 2012. Leaching and root zone salinity control. In: Wallender, W.W. and Tanji, K.K. (eds.) ASCE Manual and Reports on Engineering Practice No. 71 Agricultural Salinity Assessment and Management. 2nd Edition. ASCE, Reston, VA. p. 371-403.

Goldberg, S.R., Lebron, I., Seaman, J.C., Suarez, D.L. 2012. Soil colloidal behavior. In: P.M. Huang, Y. Li and M.E. Sumner (eds.) Handbook of Soil Sciences Properties and Processes (2nd Edition). CRC Press, Taylor and Francis Group. Boca Raton, FL. Chapter 15. pp: 15-1 - 15-39.

Last Modified: 8/22/2014
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