Potential Groundwater Pollution Research Articles

Produced water, money water, living water: Anthropological perspectives on water and fracking

Advances in hydraulic fracturing (aka “fracking”) technologies and horizontal drilling have enabled the extraction of previously unviable unconventional oil and gas resources. However, as global environmental concerns have become more prominent and unconventional oil and gas developments have moved ever closer to residential centers, public scrutiny of the industry and its methods and impacts of extraction have increased. Water impacts feature prominently among the contemporary societal concerns about fracking. These concerns include the large water requirements of the process itself, as well as concerns about the potential pollution of groundwater and the (underground) environment more broadly. Anthropologists have undertaken qualitative field research on unconventional gas developments in a variety of settings, largely among local communities in regions of extraction. The perspectives employed by anthropologists are commonly drawn from the broader social science literature, including the anthropology of water and natural resources, science and technology studies, studies of social movements, and studies which examine the energy‐society nexus. Based on the shortcomings of the published anthropological accounts, interdisciplinary research collaboration with hydrologists, engineers and economists, as well as a more fulsome engagement with the variety of hopes, fears and dreams of fracking and unconventional gas, is recommended. WIREs Water 2018, 5:e1272. doi: 10.1002/wat2.1272This article is categorized under: Engineering Water > Sustainable Engineering of Water Science of Water > Water Quality Human Water > Methods

Application of Zeolites for Sustainable Agriculture: a Review on Water and Nutrient Retention

Developing urbanization, water shortage, watercourse pollution, and demands for more food due to population growth require a more efficient water irrigation and fertilizer application. Retaining nutrients and water in agricultural soils brings about higher crop yields and prevents pollution of water courses. Among different solutions, zeolites, which are environmental friendly, ubiquitous, and inexpensive, have been extensively employed in agricultural activities. These minerals are considered as soil conditioners to improve soil physical and chemical properties including infiltration rate, saturated hydraulic conductivity (K s), water holding capacity (WHC), and cation exchange capacity (CEC). Natural and surface-modified zeolites can efficiently hold water and nutrients including ammonium (NH4 +), nitrate (NO3 −) and phosphate (PO4 3−), potassium (K+), and sulfate (SO4 2−) in their unique porous structures. Their application as slow-release fertilizers (SRFs) are reported as well. Therefore, zeolite application can improve both water use efficiency (WUE) and nutrient use efficiency (NUE) in agricultural activities and consequently can reduce the potential of surface and groundwater pollution. This review paper summarizes findings in the literature about the impact of zeolite applications on water and nutrient retention in the agriculture. Furthermore, it explores benefits and drawbacks of zeolite applications in this regard.

Lignin and ethylcellulose in controlled release formulations to reduce leaching of chloridazon and metribuzin in light-textured soils

In this research, controlled release formulations (CRFs) of the herbicides chloridazon and metribuzin, identified as potential leachers, have been evaluated in soils with different texture. To prepare the CRFs, ethylcellulose (EC) and dibutylsebacate (DBS) have been used as coating agents in lignin-polyethylene glycol based formulations.Mobility experiments have been carried out in two light textured soils (sandy and sandy-loam). Breakthrough curves have shown that the use of CRFs reduces the presence of chloridazon and metribuzin in the leachate compared to technical and commercial products, being the lignin CRF coated with EC and DBS the most efficient to diminish the herbicide leaching.Mass balance study has shown a higher amount of chloridazon and metribuzin recovered in soils when these herbicides were tested as CRFs compared to technical and commercial products. The gradual release of herbicides from the CRFs resulting in a rather available levels of chloridazon and metribuzin in soil for a longer time. A good correlation between percentages of herbicide recovered in leachates and T50 values (time corresponding to 50% release of herbicide in water) was obtained, which allows to select the most appropriate CRF in each agro-environmental practice to reduce the potential pollution of groundwater by chloridazon and metribuzin.

Vertical distribution of archaeal communities associated with anaerobic degradation of pentabromodiphenyl ether (BDE-99) in river-based groundwater recharge with reclaimed water.

When groundwater is recharged with reclaimed water, the presence of trace amounts of biorefractory pentabromodiphenyl ether (PBDE, specifically BDE-99) might cause potential groundwater pollution. A laboratory-scale column was designed to investigate the distribution of the community of archaea in this scenario and the associated anaerobic degradation of BDE-99. The concentration of BDE-99 decreased significantly as soil depth increased, and fluorescence in situ hybridization (FISH) analysis suggested that archaea exerted significant effects on the biodegradation of PBDE. Through 454 pyrosequencing of 16s rRNA genes, we found that the distribution and structure of the archaeal community associated with anaerobic degradation of BDE-99 in the river-based aquifer media changed significantly between different soil depths. The primary debrominated metabolites varied with changes in the vertically distributed archaeal community. The archaea in the surface layer were dominated by Methanomethylovorans, and the middle layer was mainly composed of Nitrososphaera. Nitrosopumilus and Nitrososphaera were equally abundant in the bottom layer. In addition, Methanomethylovorans abundance depended on the depth of soil, and the relative abundance of Nitrosopumilus increased with increasing depth, which was associated with the oxidation-reduction potential and the content of intermediate metabolites. We propose that Nitrososphaera and Nitrosopumilus might be the key archaeal taxa mediating the biodegradation of BDE-99.

Vegetation as the Bioindicator of Human-induced Degradation in Karst Landscape: Case Study of Waste-filled Dolines

Mismanagement practices, such as unsustainable waste disposal, created many degraded sites. In karst landscapes, old uncontrolled landfills are often located in dolines (sinkholes). Buried waste material in dolines represents degradation of landform, habitats and a potential danger of groundwater pollution. Buried waste provides heterogeneous ecological conditions on the surface, thus plant communities or individual plant species that developed on the surface of landfills can be used as a bioindicators of waste-filled doline sites and therefore indicators of land degradation. We aimed to discover the potential of vegetation to detect unknown locations of old dump-sites in suffusion dolines in Logasko polje (Dinaric Karst, Slovenia), either by plant communities or by plant species. We aimed to ascertain whether vegetation can indicate the dumping period by estimation of community succession stage. Locations and the age of waste-filled dolines (doline-dumps) were preliminary identified by a historical landscape study. Thus, we used time series of aerial photographs and digital photogrammetry tools for 3D modelling of historical terrain. Ecological evaluation was based on sampling the floristic composition of plots (5x5 m). We analysed ecological conditions by Ellenberg bioindicator values, structure by life history traits and naturalness by hemerobic levels of plants. We studied in detail 30 up to 50-years-old waste-filled dolines that are interspersed by dry and mesic grasslands. Ecological evaluation demonstrated that the main driver of ecological diversity at doline-dumps is the time at which the doline was backfilled and succession started. Annual and eutrophic communities dominate the youngest doline-dumps, middle aged doline-dumps are covered by nitrophilous perennial forbs and, finally, communities developed towards mesic grassland. We conclude that plant communities in combination with diagnostic plant species can be used as a bioindicators of doline-dumps in agricultural landscape of Logasko polje and can therefore indicate the sites of potential groundwater pollution sources but not the type of long-time buried waste. Key words: suffusion dolines, plant communities, waste dumping, Ellenberg indicator values, polje.

Potential groundwater pollution from improper oil and metal waste disposal in Suame, Ghana

Suame is an industrialized hub in Kumasi, Ghana, that is noted for vehicle repairs and servicing, sale of automobile spare parts, and metal fabrication. Some of these activities generate huge volumes of waste oil and metals that are often disposed off indiscriminately into the environment. These could pose a threat to the quality of groundwater in the area, especially if they continuously accumulate in the environment. This study, therefore, investigated the potential impact of the waste disposal on groundwater quality in the area. The methods employed involved mapping all the potential waste oil spillage sources and sampling the soils in such areas (at 0 – 30 and 30 – 60 cm depths) and groundwater supply points for laboratory analyses to determine the presence of the waste. In all, 36 samples (comprising 12 soil and 24 groundwater) were analysedfor the presence of heavy metals including Cd, Ni, Cu, Pb, Zn and Cr, which were used as traceelements for the presence of the waste in the samples. Computedgeo-accumulation indices from the results show the soils are moderately to heavily polluted with Cd and Pb whilst the groundwater, when compared to the WHO drinking water guidelines, is polluted with Pb and Ni. Althoughthe source of the high Pb content observed could be attributed to its transport directly from the activities in the area, the presence of high Ni makes it inconclusive since the Ni in the soil was within the concentration expected of the parent rock geochemistry. This notwithstanding, the study has indicated that groundwater in the area is not safe for human consumption unless the lead and nickel concentrations are reduced to acceptable standard for drinking.Keywords: Groundwater quality, pollution, waste disposal, Suame, Ghana

Valorization of Organic Wastes to Reduce the Movement of Priority Substances Through a Semiarid Soil

In this work, we examined the effect of two different organic wastes, composted sheep manure and coir, on the sorption, persistence, and mobility of three pesticides (alachlor, chlorfenvinphos, and chlorpyrifos) included as priority substances in European Directive 2013/39/EU. With this aim, leaching studies were conducted using disturbed soil columns filled with a typical agricultural soil (hipercalcic calcisol) from a semiarid area (southeastern Spain) to determine their potential for groundwater pollution. The three compounds were found in leachates of unamended soil although in different proportions: 53% (alachlor), 9% (chlorfenvinphos), and 6% (chlorpiryfos). The addition of organic wastes significantly increased the sorption of the studied pesticides. As a consequence, the half-lives of the studied pesticides were higher in amended than in unamended soils. A marked reduction of the amount recovered in leachates was observed in the amended soils, except for chlorpiryfos, whose recoveries barely changed. According to their potential groundwater pollution calculated as the groundwater ubiquity score (GUS) index, alachlor and chlorfenvinphos show medium leachability while chlorpiryfos is unlikely to leach.

Model-based assessment of groundwater vulnerability for the Dalyan Region of southwestern Mediterranean Turkey

The Dalyan Region that drains into a complex lagoon system is located on the Mediterranean Sea coast of southwest Turkey. There are no large streams in the area, indicating that a considerable amount of freshwater draining into the lagoon is expected to be based on groundwater inflows and that groundwater quality is an important issue for the lagoon ecosystem. Since the lagoon and its watershed are within an environmental special protection area, planning preventive and mitigative measures toward water quantity and quality, including groundwater, is crucial. Since an important step in such a study is the generation of vulnerability map of groundwater pollution, this study aims at the generation of an intrinsic groundwater vulnerability map and its assessment for the first time in the study area based on the DRASTIC method. Since the DRASTIC method requires recharge rates for the calculation of groundwater pollution potential index, these were obtained from a previous modeling study conducted in the same area, where SWAT model was used. The intrinsic vulnerability maps generated were overlaid with current land-use maps to evaluate actual groundwater pollution risk. Our analyses showed that 46% of the study area is under the high risk of groundwater pollution, where 62% of the vulnerable high-risk area is agricultural land.

Sorption of selected pharmaceuticals and pesticides on different river sediments

In the present work, the sorption ability of 17 pharmaceutical compounds, two metabolites, and 15 pesticides (34 target compounds in total) onto four different river sediments was investigated separately. Selected compounds present the most frequently prescribed pharmaceuticals in human and animal medicine and the most frequently used pesticides in agriculture. Their presence into the surface, ground, and waste waters was confirmed into the numerous papers in literature, as well as their presence into the river sediments (for some of them). However, investigations of their sorption onto the river sediments, as major natural protection from potential pollution of ground water by them is missing. Sorption in this study was investigated onto river sediments taken from rivers in the Republic of Serbia, where only less than 10% of total generated waste water passes through mainly basic treatment processes. Experiments were based on batch equilibrium procedures and obtained solutions were analyzed by previously developed and validated sensitive high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analytical methods. All results were modeled by Freundlich isotherms. Obtained results have shown that Kf coefficient values are in correlation with organic carbon content. Kd sorption coefficient values were relatively low and ranged in wide ranges for almost all compounds and sediments. That implicates on the conclusion that capacities of the investigated sorbents are not large for those compounds.

Groundwater vulnerability assessment in agricultural areas using a modified DRASTIC model.

Groundwater contamination is a major concern for groundwater resource managers worldwide. We evaluated groundwater pollution potential by producing a vulnerability map of an aquifer using a modified Depth to water, Net recharge, Aquifer media, Soil media, Topography, Impact of vadose zone, and Hydraulic conductivity (DRASTIC) model within a Geographic Information System (GIS) environment. The proposed modification which incorporated the use of statistical techniques optimizes the rating function of the DRASTIC model parameters, to obtain a more accurate vulnerability map. The new rates were computed using the relationships between the parameters and point data chloride concentrations in groundwater. The model was applied on Saveh-Nobaran plain in central Iran, and results showed that the coefficient of determination (R (2)) between the point data and the relevant vulnerability map increased significantly from 0.52 to 0.78 after modification. As compared to the original DRASTIC model, the modified version produced better vulnerability zonation. Additionally, single-parameter and parameter removal sensitivity analyses were performed to evaluate the relative importance of each DRASTIC parameter. The results from both analyses revealed that the vadose zone is the most sensitive parameter influencing the variability of the aquifers' vulnerability index. Based on the results, for non-point source pollution in agricultural areas, using the modified DRASTIC model is efficient compared to the original model. The proposed method can be effective for future groundwater assessment and plain-land management where agricultural activities are dominant.

GEOINFORMATION DATABASE FOR EVALUATION OF POTENTIAL NITRATE POLLUTION OF SURFACE WATER AND GROUNDWATER

Presented by the rationale for the structure, methods and results of creation of the geoinformation database for assessing the potential nitrate-made pollution of surface and groundwater in Odessa region. The database includes basic derivatives and digital layers of spatial information characterizing relief, hydrographic network, soil cover, land-use and spatial distribution parameters of the mathematical model of evaluation, which is selected as a regression model, developed at the Aristotle University of Thessaloniki (Greece). The database is used raster and vector spatial data models, but the basic model is a raster with the size of the raster 3710 x 3632 and with the raster cell size 92.6 m.

Characterization of Soil and Sediment Parameters of Jisike-Izombe Upper Aquifer System for Assessment of the Potential of Groundwater Pollution

The JES field, an onshore field in the Jisike – Izombe area of southeastern Nigeria had a number of oil-producing wells before it was abandoned over a decade ago. By means of soil/sediment samples retrieved from three strategically located boreholes around the field, the subsurface units were delineated and the physical characteristics of the vadose zone were determined in order to predict the groundwater pollution potential of the upper aquifer system in the area. Ground conditions were found to be approximately 1metre (3.043ft) of loamy top soil overlying about 1.2metres (3.65ft) of clayey laterite which overlies 19.4 – 24.6metres i.e (60ft – 75ft) of reddish-brown silty sand, beneath which is medium – coarse grained white sand which constitutes the aquifer system with estimated hydraulic conductivity in the range 1 x 10 -1 to 169 x 10 -1 mm/sec. Flow analysis of groundwater indicates a southwesterly flow with the River Niger as possible discharge zone. The high leaching potentials and high transmissive properties of the sediments below the clayey laterite suggests a vulnerability of the aquifer to pollution through vertical infiltration. However, borehole water quality parameters for the area show that groundwater quality is not in anyway compromised when compared to the WHO limits. Rather, it is argued that the groundwater is naturally well protected by the upper part of the vadose zone where the clayey lateritic soil with iron oxide cementation of soil particles provides an appreciable degree of barrier to downward movement of contaminants. Because of the clayey behavour of the near-surface soils and their affinity for the retention of contaminants, it is concluded that the area is not a locus of groundwater pollution. © JASEM

English

Underground coal gasification (UCG) generates potential groundwater pollution because it changes local hydrogeological parameters. Groundwater pollution is caused by diffusion and penetration of contaminants generated by UCG processes towards surrounding strata and possible leaching of residue by natural groundwater flow after gasification. A large number of hazardous water-borne contaminants were identified during different UCG operations conducted so far, and in some locations long-term groundwater contaminations were observed. Organic pollutants were detected after UCG process are phenols, benzene with its derivatives, polycyclic aromatic hydrocarbons (PAHs), heterocycles etc. and inorganic pollutants includes ammonia, mercury, zinc, sulphates, cyanides, heavy metals etc. Adsorption function of coal and surrounding strata makes a significant contribution to decrease the contaminants over time and distance from the burn cavity. Possible pollution control measures regarding UCG include identifying unsuitable zone, sitting a hydraulic barrier and pumping contaminated water out for surface disposal. The paper enumerates major pollutants identified in different UCG sites and its mitigation measures during gasification processes, and groundwater remediation after gasification.   Key words: Underground coal gasification, groundwater contamination, water influx.

Use of different organic wastes as strategy to mitigate the leaching potential of phenylurea herbicides through the soil.

In this study, the leaching of 14 substituted phenylurea herbicides (PUHs) through disturbed soil columns packed with three different soils was investigated in order to determine their potential for groundwater pollution. Simultaneously, a series of experiments were conducted to demonstrate the effect of four different organic wastes (composted sheep manure (CSM), composted pine bark (CPB), spent coffee grounds (SCG) and coir (CR)) on their mobility. All herbicides, except difenoxuron, showed medium/high leachability through the unamended soils. In general, addition of agro-industrial and composted organic wastes at a rate of 10% (w/w) increased the adsorption of PUHs and decreased their mobility in the soil, reducing their leaching. In all cases, the groundwater ubiquity score (GUS) index was calculated for each herbicide on the basis of its persistence (as t ½) and mobility (as K OC). The results obtained point to the interest in the use of agro-industrial and composted organic wastes in reducing the risk of groundwater pollution by pesticide drainage.

Characterizing land use impact on multi-tracer displacement and soil structure

Summary Leaching of solutes below the root zone has been identified as a main source of potential groundwater pollution. The occurrence of preferential flow paths in structured soils can enhance rapid leaching of solutes below the root zone. There is evidence that the actual land use can affect solute displacement by altering soil structure and the abundance of preferential flow paths. In the present study, a field experiment was conducted to assess the impacts of land use (grassland vs. no-till cropland) on profile-scale displacement of bromine (Br) and Brilliant Blue FCF. The objectives were (i) to study both solutes displacement patterns, (ii) to analyze the spatial variation and anisotropic variance structures of the solutes and controlling physical soil properties, and (iii) to analyze soil structure development as a result of the land use system and possible implications for solute displacement. Two ponding infiltration experiments with Potassiumbromide (KBr) and Brilliant Blue FCF were performed on a silt loam soil in Lexington, KY. A total of 30 mm multi-tracer solution was infiltrated on an area of 1.20 × 0.70 m. Eleven vertical profile sections (width: 1.10 m, depth: 0.80 m) were excavated in steps of 0.05 m and sampled. Dye stained areas were mapped based on digital image analysis. Small soil samples were taken for Br concentrations, soil texture, and volumetric soil water content at regular intervals along a vertical 0.10 × 0.10 m raster. Vane shear resistance was measured as a proxy for mechanical soil strength. X-ray fluorescence analysis was used to determine total Br contents and the relative SiO 2 signal intensity, the latter being used as proxy for soil particle size distribution. Although both experimental sites were under the same land use until some 10 years ago before the current land uses were established, solutes displacement differed between both land uses. The dye-stained patterns revealed a high proportion of non-equilibrium flow through vertically orientated macropores and a less permeable soil matrix at the grassland site. Continuous biological activity since transversion into grassland resulted in these macropores and the absence of any compaction in the subsoil. Large proportions of Br also infiltrated directly into the loose, densely rooted soil matrix close to the surface. Soil structure development at the no-till cropland site was mainly controlled by agricultural operations. The homogeneous Br distribution in the topsoil reflected a less dense soil matrix with a network of well-connected inter-aggregate pores. A residual plough pan restricted solute displacement to deeper soil layers or to groundwater bodies. Although ponding infiltration was applied in this study, the leaching risk for both applied solutes – Br and Brilliant Blue FCF – was rather small.

Transformation and removal pathways of four common PPCP/EDCs in soil

Pharmaceutical and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs) enter the soil environment via irrigation with treated wastewater, groundwater recharge, and land application of biosolids. The transformation and fate of PPCP/EDCs in soil affects their potential for plant uptake and groundwater pollution. This study examined four PPCP/EDCs (bisphenol A, diclofenac, naproxen, and 4-nonylphenol) in soil by using 14C-labeling and analyzing mineralization, extractable residue, bound residue, and formation of transformation products. At the end of 112 d of incubation, the majority of 14C-naproxen and 14C-diclofenac was mineralized to 14CO2, while a majority of 14C-bisphenol A and 14Cnonylphenol was converted to bound residue. After 112 d, the estimated half-lives of the parent compounds were only 1.4–5.4 d. However a variety of transformation products were found and several for bisphenol A and diclofenac were identified, suggesting the need to consider degradation intermediates in soils impacted by PPCP/EDCs.

Use of different organic wastes in reducing the potential leaching of propanil, isoxaben, cadusafos and pencycuron through the soil

In this study, we examined the effect of four different organic wastes (OW)—composted sheep manure (CSM), spent coffee grounds (SCG), composted pine bark (CPB) and coir (CR)—on the potential groundwater pollution of propanil and isoxaben (herbicides), cadusafos (insecticide) and pencycuron (fungicide) under laboratory conditions. For this purpose, leaching studies were conducted using disturbed soil columns filled with a clay loam soil (Hipercalcic calcisol). The addition of organic matter (OM) drastically reduced the movement of the studied pesticides. The results obtained point to the interest in the use of agro-industrial and composted OW in reducing the groundwater pollution by pesticide drainage.

Minimization of methabenzthiazuron residues in leaching water using amended soils and photocatalytic treatment with TiO2 and ZnO

In the present work, potential groundwater pollution by methabenzthiazuron (MTBU) and the effect of three different amendments (composted sheep manure, composted pine bark and spent coffee grounds) on its mobility were investigated under laboratory conditions. The efficiency of ZnO and TiO2 suspensions in the photocatalytic degradation of MTBU in leaching water was also investigated. The relative and cumulative breakthrough curves were obtained from disturbed soil columns. The presence and/or addition of organic matter drastically reduced the movement of the herbicide. On other hand, photocatalytic experiments showed that the addition of ZnO and TiO2 strongly enhances the degradation rate of this herbicide compared with the results of photolytic experiments under artificial light. ZnO appeared to be more effective in MTBU oxidation than TiO2. The results obtained point to the interest of using organic wastes and heterogeneous photocatalysis for reducing the pollution of groundwater by pesticide drainage.

Modeling the risk of groundwater contamination using modified DRASTIC and GIS in Amman-Zerqa Basin, Jordan

AbstractAmman-Zerqa Basin (AZB) is the second largest groundwater basin in Jordan with the highest abstraction rate, where more than 28% of total abstractions in Jordan come from this basin. In view of the extensive reliance on this basin, contamination of AZB groundwater became an alarming issue. This paper develops a Modified DRASTIC model by combining the generic DRASTIC model with land use activities and lineament density for the study area with a new model map that evaluates pollution potential of groundwater resources in AZB to various types of pollution. It involves the comparison of modified DRASTIC model that integrates nitrate loading along with other DRASTIC parameters. In addition, parameters to account for differences in land use and lineaments density were added to the DRASTIC model to reflect their influences on groundwater pollution potential. The DRASTIC model showed only 0.08% (3 km2) of the AZB is situated in the high vulnerability area and about 30% of the basin is located in the moderately vulnerable zone (mainly in central basin). After modifying the DRASTIC to account for lineament density, about 87% of the area was classified as having low pollution potential and no vulnerability class accounts for about 5.01% of the AZB area. The moderately susceptible zone covers 7.83% of the basin’s total area and the high vulnerability area constitutes 0.13%. The vulnerability map based on land use revealed that about 71% of the study area has low pollution potential and no vulnerability area accounts for about 0.55%, whereas moderate pollution potential zone covers an area of 28.35% and the high vulnerability class constitutes 0.11% of AZB. The final DRASTIC model which combined all DRASTIC models shows that slightly more than 89% of the study area falls under low pollution risk and about 6% is considered areas with no vulnerability. The moderate pollution risk potential covers an area of about 4% of AZB and the high vulnerability class constitutes 0.21% of the basin. The results also showed that an area of about 1761 km2 of bare soils is of low vulnerability, whereas about 28 km2 is moderately vulnerable. For agriculture and the urban sector, approximately 1472 km2 are located within the low vulnerability zone and about 144 km2 are moderately vulnerable, which together account for about 8% of the total agriculture and urban area. These areas are contaminated with human activities, particularly from the agriculture. Management of land use must be considered when changing human or agricultural activity patterns in the study area, to reduce groundwater vulnerability in the basin. The results also showed that the wells with the highest nitrate levels (81–107 mg/l) were located in high vulnerable areas and are attributed to leakage from old sewage water.

Modeling a Sustainable Salt Tolerant Grass-Livestock Production System under Saline Conditions in the Western San Joaquin Valley of California

Salinity and trace mineral accumulation threaten the sustainability of crop production in many semi-arid parts of the world, including California’s western San Joaquin Valley (WSJV). We used data from a multi-year field-scale trial in Kings County and related container trials to simulate a forage-grazing system under saline conditions. The model uses rainfall and irrigation water amounts, irrigation water quality, soil, plant, and atmospheric variables to predict Bermuda grass (Cynodon dactylon (L.) Pers.) growth, quality, and use by cattle. Simulations based on field measurements and a related container study indicate that although soil chemical composition is affected by irrigation water quality, irrigation timing and frequency can be used to mitigate salt and trace mineral accumulation. Bermuda grass yields of up to 12 Mg dry matter (DM)·ha−1 were observed at the field site and predicted by the model. Forage yield and quality supports un-supplemented cattle stocking rates of 1.0 to 1.2 animal units (AU)·ha−1. However, a balance must be achieved between stocking rate, desired average daily gain, accumulation of salts in the soil profile, and potential pollution of ground water from drainage and leaching. Using available weather data, crop-specific parameter values and field scale measurements of soil salinity and nitrogen levels, the model can be used by farmers growing forages on saline soils elsewhere, to sustain forage and livestock production under similarly marginal conditions.