Donald Suarez

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Papers by Donald Suarez

Effect of Mineral Weathering on Clay Dispersion and Hydraulic Conductivity of Sodic Soils

Soil Science Society of America Journal, Mar 1, 1981

On p. 289, figure captions 2 and 3 should be interchanged. In the right-hand column, Fig. 2 shoul... more

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Season-long Changes in Infiltration Rates Associated with Irrigation Water Sodicity and pH

There is increasing need to substitute low quality waters, including saline sodic waters and trea... more There is increasing need to substitute low quality waters, including saline sodic waters and treated municipal waste water for fresh water when irrigating land in arid and semi-arid regions of the world. In almost all instances low quality waters are more sodic than the fresh waters currently utilized. A major hazard associated with these waters is the reduction in water infiltration rates due to the increase in the soil exchangeable sodium percentage. Deterioration of soil; physical properties may threaten the present and future productivity of these lands. We examine the effect of even small increases in sodium on the infiltration rate over the span of a complete cropping season in a series of experiments from sodium adsorption ratio (SAR) of 0-13. Based on these controlled studies with wetting and drying cycles over 180 d conducted in container studies, we conclude that for the non-calcareous soil examined, even small increases in SAR resulted in significant decreases in infiltration rates. The deterioration in infiltration capability increased with time, suggesting that short term experiments may not characterize the long term consequences of using degraded waters for irrigation. Increased pH resulted in decreased infiltration at comparable SAR values.

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Sodium-Calcium Exchange with Anion Exclusion and Weathering Corrections

Soil Science Society of America Journal, May 1, 1991

In order to accurately model soil reclamation with concentrated electrolytes such as CaCl 2 or se... more In order to accurately model soil reclamation with concentrated electrolytes such as CaCl 2 or sea water, it must be determined if there is an effect of salinity on the Na-Ca exchange selectivity. A new procedure for determining Na-Ca selectivity in calcareous and gypsiferous soils was used to study the effects of ionic strength and mineralogy on Na-Ca exchange. Four specimen clay minerals and three whole soils were equilibrated with solutions ranging in concentration from 10 to 1000 mmol c L' 1 and at Na adsorption ratios from 1 to SO (mmol L~') 1/2. Exchangeable-cation values were corrected for calcite and gypsum dissolution as well as anion exclusion. The selectivity data were compared with other reported values for Na-Ca exchange in order to determine if there were any trends in selectivity with mineralogy or surface charge density. Generally, Na-Ca selectivity was independent of ionic strength. Vermiculite exhibited near-ideal exchange when compared with the nonpreference isotherm. There was no effect of mineralogy on the Na-Ca selectivity, even though the soils and minerals had various surface charge densities. The Gapon selectivity coefficients (K G) for the calcareous Many Farms soil (a mesic Torrifluvent) and the gypsiferous Shiprock soil (a mesic Torriorthent) averaged 0.011 and 0.013 (mmol L~')~1 /2 i respectively. Failure to correct for anion exclusion and min

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Sodium-Calcium Exchange with Anion Exclusion and Weathering Corrections

Soil Science Society of America Journal, May 1, 1991

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Spinach biomass yield and physiological response to interactive salinity and water stress

Agricultural Water Management, Aug 1, 2017

Critical shortages of fresh water throughout arid regions are forcing growers to decide among the... more Critical shortages of fresh water throughout arid regions are forcing growers to decide among the following options, applying insufficient fresh water, causing water stress, applying saline water causing salt stress or applying some combination minimizing saline water application, causing combined water and salt stress. A comprehensive approach to manage drought and salinity is to evaluate the impact of water stress and salt stress individually and then examine their interactions on plant production. To analyze salinity and water stress responses and their interaction together on spinach growth, an experiment was conducted from April 1 to May 21, 2013, using 6 different irrigation waters at electrical conductivity (EC): 0.85, 4, 7, 9, 12, 15 dS m −1. Soil moisture was recorded by sensors and stress treatments had the following soil water matric pressure control (−45 kPa), −200 to −300 kPa, and −400 to −500 kPa. We evaluated three replicates per treatment for yield, vegetative parameters, ion composition, and physiological parameters. The results showed that the spinach yield response to salt and water stress was very different. Spinach yield initially increased with salinity and subsequently decreased only when the irrigation water was EC 9 dS m −1 and above (osmotic pressure of −310 kPa). In contrast, yield decreased at the first water stress level (−230 kPa) relative to control. The additional presence of salinity stress decreased the relative yield response due to water stress. Similarly under water stress the relative yield response to increasing salinity was reduced. Although no model provided good prediction of stress response, the best predictive model (relative error) was one that considered the response to multiple stresses as the product of the response to the individual stresses.

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Inorganic Carbon

CRC Press eBooks, Dec 22, 2005

The effect of selenium on salinity stress and selenate – sulfate comparision in kale

Journal of Plant Nutrition, Jun 7, 2021

Abstract Increased salinity is a threat to arid and semiarid zone agriculture worldwide. Kale con... more Abstract Increased salinity is a threat to arid and semiarid zone agriculture worldwide. Kale consumption has increased as its nutritional and antioxidant benefits become more widely known. Compared with other vegetables, it is relatively salt tolerant. However, there is limited information on its salt tolerance, nutrient uptake under saline conditions, and physiological response. We examined the yield response, physiological parameters, and mineral nutrient content of kale grown under variable conditions of salt and Se addition in a greenhouse study. The experiment consisted of four salinity levels, four Se levels, and combined salinity treatments for a total of 16 treatments each with four replications. Salinity decreased yield when irrigated at 6 and 9 dS m−1 but not at 3 dS m−1. Selenium addition increased yield at all salinity levels but did not increase salt tolerance. Addition of 0.25 mg Se per kg of soil, corresponding to leaf Se concentrations of 1 mg kg−1, was sufficient to increase yield by an average of 11% relative to control. Kale yield loss began between 3 and 6 dS m−1 irrigation water salinity and 50% yield loss occurred at EC 6.

Selenium in Water Management Wetlands in the Semi-arid West

Hortscience, Feb 1, 1999

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Selenium Speciation of Marine Shales, Alluvial Soils, and Evaporation of California

The surface exposed shales of the Moreno and Kreyenhagen Formations are considered to be the sour... more The surface exposed shales of the Moreno and Kreyenhagen Formations are considered to be the sources of selenium (Se) that have enriched soils of the west-central San Joaqnin Valley of California. Although the total Se content for the source shales and the resulting alluvial, seleniferous soils has been reported, the distribution of Se oxidation states has not been determined in these materials. This study investigates the Se speciation trends in the seleniferous source shales, the adjacent alluvial soils, the San Luis Drain sediment to the Kesterson evaporation pond soils. The surface-exposed Moreno shales (5.21 mg total Se kg-') had half of the Se content of the less exposed Kreyenhagen shale (10.94 mg total Se kg-'). The elemental Se (Se') concentration was similar in the two shales, hut the selenate (Se+ VI), selenite (Se + IV), and selenide (Se-II) concentrations were lower in the Moreno shale as compared with the Kreyenhagen shale. The Se in the San Luis Drain sediment (83.8 mg total Se kg-') was enriched in the Se' and the Se-II fractions (91.4% of Se inventory). The soils of the Kesterson evaporation pond 4 (47.8 mg total Se kg-'), 7 (6.7 mg total Se kg-'), and 11 (5.4 mg total Se kg-') were also enriched in Se with 86, 76, and 48% of the Se inventory present in the Se" and Se-II fractions, respectively. The organic C content also decreased in the sequence, San Luis Drain, Kesterson pond 4, 7, and 11, from 33.3, 26.7, and 19.3 g C, to 15.1 g C kg-' soil material, respectively, suggesting a relationship between Se concentrations and organic C levels. A linear relationship between the sum of (Se-II and Se')-Se and organic C levels (Rr = O.%*; significant at the 0.05 level) was noted for the analyzed San Luis Drain sediment and the Kesterson soils. For the nine soil materials, an exponential relationship (R' = 0.96) was determined for the sum of (Se-II and Se')-Se and organic C contents, suggesting that the Se in the materials tested was highly associated with the soil organic matter fraction. An additional 12 Se analyses and organic C contents from Se contaminated semiarid and irrigation drainage water evaporation basin soils obtained from the literature closely fit the exponential function established for the nine soil materials. The results suggest that an initial release of organicassociated Se would be expected with increased C oxidation, along with a slower, long-term release of the refractory Se, due to the reversion of the former Kesterson wetland evaporation pond ecosystem back to a native semiarid grassland.

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Changes in the Distribution of Selenium Oxidation States with Sample Storage

Journal of Environmental Quality, Nov 1, 1997

Significant changes in the distribution of selenium (Se) oxidation states of fresh soil were note... more Significant changes in the distribution of selenium (Se) oxidation states of fresh soil were noted with oven-drying (90°C) or with outdoor storage (>5 yr) in compromised plastic containers compared with small changes in Se oxidation state distribution in air-dried samples. Compromised outdoor storage resulted in a 25% increase in the selenate (Se 6+) concentrations with a concomitant 18.4 and 5.7% decrease in elemental Se and selenite (Se 4+) concentrations, respectively, on a total Se basis. Substantial increases in phosphate-soluble selenide from 15.7% of total Se for fresh seleniferous alfalfa (Medicago sativa L.) to 32.6% phosphate-soluble Se were noted with air-dried alfalfa. The results indicate that air-drying will not substantially alter the distribution of soil Se oxidation states, but will result in a significant increase in the concentration of phosphate-soluble Se in seleniferous alfalfa residue. S ELENIUM has become one of the major elemental contaminant problems in irrigation drainage waters in the western portion of the USA due to the toxicological effects of Se on fish and wildlife. An overview of the Se problem in California evaporation ponds including the Kesterson evaporation ponds is presented by Ohlendorf and Santolo (1994). In environmental and biological samples, Se can exist in inorganic forms as elemental Se (Se°), metal selenides (Se2-), and selenite (Se 4+) and selenate (Se6÷), and as organic species with direct Se-C bonds such as methylated compounds, seleno-amino acids, and selenoproteins. Research has identified that the toxic dose of Se is very much dependent on its chemical form, with different toxicity for organic and inorganic Se compounds (Heinz et al., 1987, 1988, 1989). Thus, identification of each Se oxidation state in soil, plant, and water samples is more important than the determination of a total Se concentration (Martens and Suarez, 1997). Accurate determination of the distribution of Se oxidation states, especially in water samples, has been shown to be dependent on sample preparation and storage (Wang,

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Nonequilibrium and Multicomponent Transport Models

Agronomy, Oct 26, 2015

Long Term Weathering Rates of Twelve Mineral Fractions Isolated from a Granodiorite Derived Soil

Mineralogical Magazine, 1998

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Perspective on Irrigation Management and Salinity

Outlook on Agriculture, Dec 1, 1992

Arid and semiarid areas face increasing demands on their limited water supplies. In many regions ... more Arid and semiarid areas face increasing demands on their limited water supplies. In many regions agriculture utilizesthe bulk of the available fresh water, often exceeding the sustainable water yield and relying on utilization of subsurface reserves. Increased water demands by urban users will require greater water use efficiency by the agricultural sector as well as use of urban waste waters and under-utilized brackish waters. To date advances have been made in irrigation management, but genetic research has not altered the basic water requirements of plants.

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Linking Genetic Determinants With Salinity Tolerance and Ion Relationships in Eggplant, Tomato, and Pepper

The Solanaceae family includes commercially important vegetable crops characterized by their rela... more The Solanaceae family includes commercially important vegetable crops characterized by their relative sensitivity to salinity. Evaluation of 24 heirloom cultivars of eggplant (Solanum melongena), tomato (Solanum lycopersicum), and pepper (Capsicum spp.) from different geographic regions under salinity revealed significant variation in salt tolerance. Relative fruit yield under salt treatment varied from 52 to 114% for eggplant, 56 to 84% for tomato, and 52 to 99% for pepper. Cultivars from all three crops, except Habanero peppers (C. chinense), restricted Na transport from roots to shoots under salinity. The high salt tolerance level showed a strong association with low leaf Na concentration. Additionally, the K-salinity/K-control ratio was critical in determining the salinity tolerance of a genotype. Differences in relative yield under salinity were regulated by several component traits, which was consistent with the gene expression of relevant genes. Gene expression analyses using...

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Hydrodynamics and Chemical Transport in the Root Zone and Shallow Ground Water System: Modeling

Root Extraction of Nutrients Associated with Long-Term Soil Management

Advances in Soil Science, 1992

A major charge to agricultural research is to identify management practices that maintain long-te... more A major charge to agricultural research is to identify management practices that maintain long-term soil fertility and crop production with reduced chemical inputs and tillage operations. Of prime importance is gaining a fundamental understanding of soil physical, chemical, and biological factors limiting crop production. In general, soil water content of the root zone is the major limitation to root growth, but many other dynamic variables also affect the root extraction of nutrients.

Evaluation of salt-tolerant forages for sequential water reuse systems

Agricultural Water Management, Nov 1, 2004

Implementation of the saline drainage water reuse system proposed for the westside of the San Joa... more Implementation of the saline drainage water reuse system proposed for the westside of the San Joaquin Valley (SJV) of California requires development of sustainable cropping systems, which incorporate useful, salt-tolerant agronomic species. Ion composition in the saline drainage effluents present in the SJV is unique, with Na + , SO 4 2À , Cl À , Mg 2+ and Ca 2+ predominating in that order. To identify potentially suitable crops for reuse systems, 10 forages were tested in greenhouse sand cultures located at USDA-ARS George E. Brown Jr. Salinity Laboratory, Riverside, California. Crops were: alfalfa (Medicago sativa L.) cvs. 'Salado' and 'SW 9720'; narrowleaf trefoil (Lotus glaber Greene) cv. 'PI 608022'; broadleaf trefoil (L. ulginosus Schk.) cv. 'Big'; tall wheatgrass (Agropyron elongatum (Host) Beauv.) cv. 'Jose'; alkali sacaton (Sporobolus airoides Torr.); kikuyugrass (Pennisetum clandestinum Hochst. Ex Chiov.) cv. 'Whittet'; paspalum (Paspalum vaginatum Swartz) cvs. PI '299042' and 'Polo'; and bermudagrass (Cynodon dactylon L. Pers.) cv. 'Tifton'. Two saline treatments, 15 and 25 dS m À1 , were imposed. Shoots were sub-sampled for mineral ion analysis when the forages were harvested. Patterns of shoot ion concentrations were unique for each species and varied with salinity level, external ion ratios, harvest date and plant age. Plant preference for K + over Na + did not appear to be a reliable predictor of salt tolerance. Salt-tolerant crops, such as kikuyugrass and bermudagrass, were highly selective for K + (S K,Na $ 200 to 400), whereas selectivity www.elsevier.com/locate/agwat Agricultural Water Management 70 (2004) 121-135

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The effect of total carbon on microscopic soil properties and implications for crop production

Journal of Arid Land, Jun 20, 2012

Soil structure is a dynamic property affected by physical, chemical, and microbiological processe... more Soil structure is a dynamic property affected by physical, chemical, and microbiological processes. Addition of organic matter to soils and the use of different management practices have been reported to impact soil structure and crop production. Moderation in soil temperature and increases in microbial activity and soil water retention are often suggested as reasons for the rise in crop yield when organic matter is added to the soil. Less is known about the direct effect of changes in soil structure on crop production. A field experiment was conducted to study the effect of summer cover crop and in-season management system on soil structure. The experiment was a nested design with summer cover crop as the main plot and management system as the subplot. Summer cover crop treatments included cowpea (Vigna unguiculata L. Walp.) incorporated into the soil in the fall (CI), cowpea used as mulch in the fall (CM), sudangrass (Sorghum vulgare) incorporated into the soil in the fall (S), and dry fallow or bare ground (B). Management systems were organic (ORG) and conventional (CNV) systems. Lettuce (Lactuca sativa L.) and cantaloupes (Cucumis melo L.) were cultivated in rotation in the plots for three consecutive years using the same cover crops and management systems for each plot. Disturbed and undisturbed soil cores were collected at the end of the third year and used for laboratory experiments to measure physical, chemical, and hydraulic properties. Image analysis was used to quantify soil structure properties using a scanning electron microscope on thin sections prepared from the undisturbed soil cores. We found that total soil carbon was correlated with porosity, saturation percentage, and pore roughness. Pore roughness was correlated with crop production in general and with marketable production in particular. We found that the higher the complexity of the pore space, the more water retained in the soil, which may increase soil water residence and reduce plant water stress.

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Variations in Soil Stability within and among Soil Types

Soil Science Society of America Journal, Sep 1, 1992

One of the most important considerations when im,gating with mar ginal waler or managing sodic so... more One of the most important considerations when im,gating with mar ginal waler or managing sodic soils is maintaining or restoring. good soil structure_ Recommendations developed to date have considered water quality parameters and assumed that soils behaved similarly. We examined the Hocculation behavior of three different types of micaceous soils at variable electrolyte concentration, sodium adsorp tion ratio [SAR Na/(Ca + Mg)o.S, where concentrations are ex pressed in mmol L-'); and pH_ The variability in critical coagulation concentration (CCC) among soil types and among samples within the same soil type also was investigated. 1;he CCC values were calculated at electrolyte concentrations of 2, 5, 10, 20, and 40 mmol. L-, at SAR values of 5,10,20,40, and 80 (mmol L-')0.5, and at pH values of 6_0, • 7.5, and 9.0. The variability in CCC was large among soil types of similar mineralogy, and even within the same soil type. This varia bility was greater at higher pH,suggesting that at least part of the ..ariation results from differences in variable charge. Increasing pH had an adverse effect on dispersion, especially when the SAR was high enough to break apart the illite domains. There was no relationship among CCC, organic maUer, and Fe and AI oxide contents for the soils studied. In the range investigated (1-4 g organic C kg-' 5011), only the Ebro Basin soils showed increases in CCC witb increasing , organic matter at high pH and SAR. Aggregate stability was measured on aggregates of the soils after saturation with solutions having salt concentrations of 2 and 40 mmol L-'; SAR values of 5, 20, and 80 c (mmo! L-')"'; and pH values .of 6.0,7.5, and 9.0. No relation was found between the Hocculation test data and the aggregate stability results. Apparently tl'\e measured parameters' in these two tests are governed by different soil factors. Particle-size distribution and po rosity, as well as the drying and rewetting processes, exert a major influence on aggregate stability, but are not considered in flocculation tests. Regardless of the test used, differences. in results for samples of the same soil type preclude the use of generalized tbreshold lines for soil stability. ' M AINTENANCE OF SOIL STABILITY is an important aspec't of agricultural management. Poor aggre gate stability; clay dispersion, and low infiltration are often aggravated in arid soils by chemical conditions such as high exchangeable Na.. Early recommendations for maintaining good '. soil structure advocated reducing the ESP of soils to < 15 by the application of chemical amendments (U_S.Sa linity Laboratory Staff, 1954)_ Subsequently, stability lines including solution salt concentration as well as ESP were recommended (e.g .• Quirk and Schofield, 1955; Rhoades, 1982; Ayers and Westcot, 1985), since it had been noted that increasing solute concentration increased soil stability. Additional variables such as Fe oxides (McNeal and Coleman, 1966), organic matter (Kemper and Kock,

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Gypsum Effect on the Aggregate Size and Geometry of Three Sodic Soils Under Reclamation

Soil Science Society of America Journal, 2002

the soil particles and aggregates. Dispersion or flocculation of clays occurs because of the repu... more the soil particles and aggregates. Dispersion or flocculation of clays occurs because of the repulsion of similar Reclamation of sodic soils is imperative in many areas where detericharged clay platelets and the ability of the soil solution oration of land and water resources is in progress. While the chemical mechanisms involved in the reclamation of sodic soils are well de-to mitigate this repulsion. Irreversible changes in soil scribed and understood, the in situ physical processes undergoing structure may occur when clay particles become disduring the salt leaching and cation substitution are normally not taken lodged if, for example, the electrolyte level is decreased into consideration. Three sodic soils mixed with different amounts of or the Na fraction increases. gypsum were packed in columns and leached under saturated condi-There are several studies in which the decrease of K sat tions for a period of time between 1 and 3 mo. Saturated hydraulic has been related with increases in Na content (McNeal conductivity (K sat) was measured and a thin section was prepared for

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Donald Suarez

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