Carbon Dioxide Partial Pressure in Lysimeter Soils

The carbonate chemistry portion of mechanistic salinity models is generally the weak link in describing salt reactions in soils. This is primarily due to a lack of available soil atmosphere CO2 data. Carbon dioxide concentrations were measured at 0.25, 0.50, and 0.75 m depths in 0.30 m diam lysimeters containing 1.0 m of sodic soil. Four non-cropped treatments included a check, gypsum, fresh manure, and chopped alfalfa irrigated weekly with 70 mm (5.0 l) of tap water (EC-0.7 and SAR= 1.7). Six cropped treatments included barley (Hordeum vulgare), alfalfa (Medicago sativa L.), Sordan (Sordan is a trade name for a sorghum (Sorghum bicolor), sudangrass (Sorghum sudanese hybrid], Sordan + leaching, cotton (Gossypium hirsutum L), and tall wheatgrass (Agropyron elongatum). The cropped lysimeters were irrigated at 1.25 times the consumptive use since the previous irrigation (0.20 leaching fraction). Soil PCO2 values were decreased by the gypsum treatment and increased by all other treatments as compared to check. Cotton and barley had the lowest PCO2 values for the cropped treatments and Sordan had the highest (frequently above 16 kPa). The PCO2 levels were affected by applied organic matter source, crop, plant growth rate, irrigation water application and leaching

Sodium Adsorption Ratio-Exchangeable Sodium Percentage Relationships in a High Potassium Saline-Sodic Soil

Exchangeable sodium percentage (ESP) and sodium absorption ratio (SAR) values were obtained from 692 soil samples and their saturation extract solutions. All samples were from a Declo silt loam (coarse, loamy, mixed, mesic, Xerollic Calciorthids) phase that was saline-sodic and very high in potassium (K). Some samples contained as much as 80 meq K/l in the saturation paste extract. In those samples where the Na : K ratio was less than 4 : 1 the measured ESP was considerably lower at a given SAR than is usually observed in high Na soils. As the soluble salts were leached from this soil in lysimeters and under field conditions, with or without Ca amendments, the soil did not become sodic nor have decreased infiltration rates when irrigated with low salt water (200 µmhos /cm). The exchangeable K was more tightly held on the exchange sites than were Ca, Mg, or Na, thus reducing the high Na effects

Management of soil salinity in South East Australia: Impressions of a visitor

Officers of the Riverina Branch of the Australian Society of Soil Science Inc. are to be complimented for the fine conference programme and field trip. It brought together a "critical mass" of individuals and disciplines involved in the salinity problems of the area. This kind of gathering needs to be promoted every four to six years. The interactions between disciplines was very stimulating to all those involved. The following comments are not meant as criticisms, but rather as the perceptions of an outsider and newcomer, of topics that appear to warrant more thought and investigation

Coefficients for estimating SAR from soil pH and EC data and calculating pH from SAR and EC values in salinity models

Data from highly weathered, low pH, sodic Australian soils have been used to develop a method for estimating soil exchangeable sodium percentage (ESP) or soil extract sodium adsorption ratio (SAR) from soil pH and electrical conductivity (EC) data. The method can also be used to calculate soil pH in soil salinity models using SAR and EC values. The pH was calculated as pH - A + (B x SAR^1/2)/(1 + C x EC). Rewriting the equations in terms of SAR (or ESP), gives SAR (or ESP) - [(pH - A)(1 + C x EC)/B]2 . This study was conducted to determine whether these same methods could be used to predict the pH and SAR values for arid climate soils that are only slightly weathered and are often sodic under natural conditions. Existing pH, EC, and SAR data from Declo loam (coarse-loamy, mixed, mesic, Xerollic Calciorthids), Freedom silt loam (fine-silty, mixed, mesic, Xerollic Calciorthids), and Mazuma sandy loam (coarse-loamy, mixed (calcareous), mesic Typic Torriorthents) were used to calculate the A, B, and C coefficients for the three high sodium soils. Coefficients obtained for a particular soil site were then used to predict pH or SAR of soil samples at additional sites and the correlation between calculated and measured values were determined. The A values for the Idaho soils are about 0.8 greater than those for the Australian soils, which were not completely base saturated. The Australian soils B values were about twice that of the calcareous Idaho soils, and the C values were not significantly different for the Australian and Idaho soils. In both cases the A coefficient values were slightly smaller than or nearly equal to the smallest pH values in a particular data set. Using coefficients from one location of a particular sodic or saline-sodic soil to predict pH or SAR of the same soil, at a second location, was shown to be practical. Each soil type, however, requires its own set of coefficients. These relationships provide a rapid field method for estimating SAR or ESP from easily obtainable EC and pH data once the A, B, and C coefficients are determined for a particular soil. They also provide a method for pH calculation in soil salinity models that take into account soil EC and sodium effects on pH

Potentiometric Titration of Sulfate Using A Lead-Mercury Amalgam Indicator Electrode

A lead sensitive indicator electrode was constructed with a 70 percent lead and 30 percent mercury amalgam billet. Sulfate concentrations in pure solutions, natural waters, and soil saturation extracts were determined potentiometrically using the lead-mercury amalgam indicator electrode and a standard calomel reference electrode. Sulfate concentrations over the range 0.4 to 20 milliequivalents sulfate per liter were determined with an automatic titrator and compared to a turbidimetric method for accuracy and precision. The values obtained by the two methods from twelve saturation extracts and three subsurface drainage waters were not significantly different and the potentiometric method was generally more precise. The automatic sulfate titration method has the advantages of increased sensitivity and speed

Sample preparation for determining ions in dark colored sodic soil extracts

Saturation paste extracts of sodic soils (pH >8.5 and electrical conductivity <4.0 dS m-1) usually contain dark colored, suspended organic matter that interferes with colorimetric, turbidimetric, potentiometric, ion chromatographic (IC) and to a lesser extent, atomic absorption spectrophotometry and flame emission procedures. Bicarbonate also interferes with formate analysis by IC in those extracts. This study was conducted to develop a simple pretreatment method for removing those interferences without introducing new interferences. Fifteen mL extract samples were titrated to pH 8.4, then to 4.7 and finally to a pH range of 3.0 to 3.5 with standardized H2S04 or HCl. The first two end points determine CO23- and HCO3 concentrations. The third pH adjustment removed the HCO3 interference from the formate analysis and allowed for organic matter coagulation. The acid choice depended on whether CL- or SO24- was to be measured later. To remove the organic matter, the extracts were centrifuged and forced through a 0.2-µm nylon filter following 0.08 M AlCl3 or 0.04 M Al2(SO4)3 treatments. Formate and acetate concentrations were determined by IC. The concentrations were determined by colorimetric, and IC procedures. The SO24- concentrations were measured turbidimetrically and by IC. The extracts were analyzed for Ca2+ and Mg2+ by atomic adsorption spectrophotometry, and Na+ and K+ by flame emission. Titrating the extracts as described provided CO23- and HCO3- data, removed the HCO3 interference from the formate analysis, and allowed Al3+ to coagulate the suspended organic matter, which was then removed by centrifugation and filtration. This pretreatment did not interfere with any of the analytical methods tested, except for cation determination by IC and anion determination by IC when methyl orange was used as a pH end point indicator

Salt- and sodium-affected soils

This publication is designed to help identify salt- and sodium-affected soils, the salt or sodium sources, how to take soil and water samples, how to reduce the harmful effects of salts and sodium and where to get advice in making reclamation and management decisions for each situation. Salt- and sodium-affected soils, and waters used for irrigation, present a complex combination of problems and possible solutions. It is not the intent here to cover all technical aspects or possible treatment approaches available, but rather to give a simplified overview of what should be considered in diagnosing and managing salt- and sodium-affected soils and irrigation waters. Since summarizing the effects of salt and sodium on soils and plants is difficult without using the appropriate terminology, a glossary is included

Methods for treating bone deficit conditions with benzothiazole

" Compounds containing two aromatic systems covalently linked through a linker containing one or more atoms, or ""linker"" defined as including a covalent bond per se so as to space the aromatic systems at a distance 1.5-15 .ANG., are effective in treating conditions associated with bone deficits. The compounds can be administered to vertebrate subjects alone or in combination with additional agents that promote bone growth or that inhibit bone resorption. They can be screened for activity prior to administration by assessing their ability to effect the transcription of a reporter gene coupled to a promoter associated with a bone morphogenetic protein and/or their ability to stimulate calvarial growth in model animal systems. "Board of Regents, University of Texas Syste

Cheese whey as an amendment to disturbed lands: Effects on soil hydraulic properties

Whey, the liquid byproduct of cheese production, can improve minesoils by increasing the aggregate stability of soils high in sodium or susceptible to erosion. Whey effects on soil hydraulic properties, however, are not known. In this experiment, we determined whey effects on infiltration rates (at water potentials of -30 mm or less) and unsaturated hydraulic conductivities of surface soil horizons after a winter wheat (Triticum aestivum L.) growing season. The experimental design was a randomized complete block with three replications of four liquid whey application treatments, totaling either 0, 202, 404, or 808 Mg/ha (control, low, medium, and high, respectively). In Fall 1992 near Kimberly, ID, a field of Portneuf silt loam (Durixerollic Calciorthid) was leveled, subsoiled, then roller-harrowed twice. After planting Malcolm wheat on September 15, we furrowed all plots and then constructed a berm around each. At 3-week intervals beginning on May 19, 1993, either zero, one, two, or four flood applications of 202 Mg/ha of whey were made to each plot, without subsequent tillage. After August wheat harvest, a tension infiltrometer was used to measure vadose zone, unsaturated flow characteristics in the bottom of undisturbed furrows, where most whey had infiltrated. Infiltration rates at potentials of -60 and -150 mm decreased linearly as whey applications increased from 202 to 808 Mg/ha. At a potential of -60 mm, hydraulic conductivity increased but then decreased with whey additions. In short, soil hydraulic properties were little affected by surface whey additions of 404 Mg/ha or less

Cheese whey as a soil conditioner

Whey is the liquid by-product of cheese and cottage cheese manufacture from milk. Each kg of cheese produced results in the production of about 9 kg of whey. In 1993, the U.S. cheese and cottage cheese industry produced approximately 23 x 10^6 m^3 (6 x 10^9 gal) of whey (National Agricultural Statistics Service, 1994). Most of this is used directly as livestock feed or concentrated or dehydrated and used in human food and animal feed manufacture. Depending on the locality and economic factors, 20 to 100% of the whey produced is applied for beneficial effects on soils, or is land applied as a disposal procedure