Earl O. Skogley

The phytoavailability soil test - PST.

Abstract Current soil tests are based on single and multiple nutrient extractions with a wide range of chemical solutions. For most nutrients this approach provides an “index”; of plant availability, but it may not be accurate on specific soils or in certain regions. Major problems with chemical extraction soil testing cannot be solved because they are inherent in the approach. The Phytoavailability Soil Test (PST) is a simplified soil‐extraction methodology based on ion‐exchange‐resin extraction of nutrients from saturated paste soil samples. The need for drying and grinding soil samples is thus eliminated. PST provides a “universal”; extraction for all nutrients. It mimics nutrient accumulation in plants, thus providing a more theoretically accurate basis for soil testing. PST also provides a system which can be “standardized”; for use in all regions. Factors which influence the rate and amount of resin‐extracted nutrients, including type of resin, shape of resin bag, soil water content, microbial activ...

Nutrient adsorption kinetics of ion exchange resin capsules: A study with soils of international origin

Abstract A method based on use of ion exchange resin capsules was evaluated for simultaneous extraction of plant available nutrients (N, P, K, Ca, Mg, and Na) to determine its utility as a general soil testing procedure for soils of world‐wide origin. Nutrient release kinetics of soils representing many soil orders were measured in saturated soil paste during 14 d incubation periods. Suppressed ion chromatography was suitable for simultaneous determination of five cations in extracts from the resin capsules. The fractional power equation described well the cumulative nutrient adsorption by the resin as a function of time for all nutrients. The constants a and b in this equation combine quantitative levels of nutrient availability as well as transport and release mechanisms in the soil. Ranges of a and b in soil are presented and their relationships to other soil properties are discussed. A simple method for calculating kinetic constants in the power function based on only two incubation times is proposed....

The universal bioavailability environment/soil test unibest

Abstract The Universal Bioavailability Environment/Soil Test (UNIBEST) provides a new methodology for testing and monitoring soil, the vadose zone, water‐saturated strata, free water, or other media. The methodology is based on placement of a uniform, rigid, spherical, porous capsule of mixed‐bed ion‐exchange resin into the medium to be tested. Solutes, both cations and anions, are independently and selectively adsorbed, based on their concentration in the solution phase and their rate of diffusion to the resin sink. The exchange capacity of the resin capsule functions as an effectively infinite sink, allowing continuous adsorption of elements in a manner somewhat analogous to absorption by living organisms. Thus, quantities of elements accumulated in the capsule during a selected time relate to their “bioavailability.”; The test is being developed as a “universal”; single‐extraction approach for laboratory soil testing. However, capsule characteristics allow for in‐situ methodology development to replace...

Effect of sample pretreatment on extractable soil potassium

Abstract Effect of soil sample treatment on potassium (K) release characteristics of Northern Great Plains soils was studied. Samples of agricultural soils were extracted with neutral normal ammonium acetate for K after selected pretreatment. Field‐moist sub‐soil samples with approximately 100 mg/kg extractable K release nearly double this amount after they were air on oven‐dried prior to analysis. The percentage increase in extractable K in dried soils decreased as the K level in the field‐moist soils increased. At 420 and 500 mg/kg, the extractable K content of air‐dried and oven‐dried soils, respectively, equaled the extractable K content of field‐moist samples. Above these concentrations, drying decreased extractable K. Oven‐drying (60 C) affected extractable K more severely than did air‐drying the soils. Drying and grinding the 15‐ to 30‐cm depth samples significantly increased exchangeable K compared to field‐moist samples. Rehydration of oven‐dried soils to 40% water did not affect extractable K. H...

Carbonaceous Resin Capsule for Vapor-phase Monitoring of Volatile Monoaromatic Hydrocarbons in Soil

Soil and groundwater contamination by organic substances is a major environmental and health concern, but methods of direct, in situ evaluation of quantities and forms of these contaminants are generally highly limited. The resin capsule system (RCS) has been developed for use in the laboratory or in the field for inorganic chemicals, and its application has been extended to include organic chemicals by incorporation of carbonaceous, hydrophobic adsorbers in the capsules. The objective of this study was to determine the efficacy of carbonaceous resin capsules for detecting benzene, toluene, ethylbenzene, and xylene (BTEX) vapors diffusing through a soil column, and to investigate sensitivity to environmental factors that influence vapor phase diffusion. Results show that the RCS can serve as a trap for organic vapors, and that quantities of BTEX accumulated are influenced by soil texture and water content during extended adsorption times. The nature of these effects, as measured by the RCS, was similar to expectations, based on previously reported results from studies involving direct measurements. These results provide evidence that the RCS could be developed to serve as a simple, inexpensive, direct, in situ methodology for monitoring volatile organic chemicals in soils.

Carbonaceous resin capsule for vapor-phase monitoring of volatile hydrocarbons in soil: partitioning and kinetic model verification

The resin capsule system (RCS) was tested as a means of providing data on the presence and forms of volatile hydrocarbons. Results indicated that resin capsules provided data showing sensitivity to soil variables (texture and moisture content) and time. The objectives of this paper are to evaluate the RCS methodology and to determine whether carbonaceous resin capsules provide results that can be described by fundamental chemical partitioning and kinetic principles. Findings revealed a significant relationship between quantities of benzene, toluene, ethylbenzene, and xylene adsorbed on the capsule and quantities partitioned into the vapor phase. Kinetic evaluation indicated that the vapor adsorption by the resin capsule is regulated by diffusion processes. No verification of rate-limiting processes was possible due to limitations imposed by the experimental design, but it appears that during early stages, adsorption rate was limited by vapor diffusion through the soil. The resin capsule data also reflected differences that would be expected due to properties of the organic liquids present. These results provide further evidence that the RCS could be developed to suggest direct in situ monitoring to reveal quantities and nature of organic substances in soils.