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James E. Altland, James C. Locke, and Charles R. Krause

Cation exchange capacity is a commonly used soil chemical property that describes the maximum quantity of cations a soil or substrate can hold while being exchangeable with the soil solution. Cation exchange capacity is often associated with a soil

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Janet F.M. Rippy and Paul V. Nelson

be neutralized and in the buffering capacity of moss peats. Two factors that may affect the neutralization requirement and buffering capacity of moss peat among batches are cation exchange capacity (CEC) and base saturation [fractional calcium (Ca 2

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Wei Qiang Yang and Barbara L. Goulart

Aluminum (Al) uptake by and root cation exchange capacity (CEC) of mycorrhizal (M) and nonmycorrhizal (NM) blueberry (Vaccinium corymbosum L.) plants were studied. Root CEC was higher in M plants than in NM plants, but total and root Al contents were higher in NM plants. Leaf Al content was higher in NM than in M plants after 1 and 5 hours of exposure. The aurintriboxylic acid stain for Al indicated the presence of Al in the M symbiont. Despite a larger root system and higher root CEC, regression analysis indicated roots of M plants absorbed less Al in the first 5 hours, suggesting that Al sequestration in the M symbiont is responsible for reduced total Al uptake. Differences in dry matter partitioning between M and NM plants were also observed.

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Wei Qiang Yang and Barbara L. Goulart

Aluminum (Al) uptake and root cation exchange capacity (CEC) of mycorrhizal (M) and non-mycorrhizal (NM) blueberry plants (Vaccinium corymbosum L.) were studied. Mycorrhizal roots took up more Al than non-mycorrhizal roots over a 48-h period. Different patterns of Al uptake occurred between M and NM roots. The M roots contained more Al at hour 1, followed by a deep decrease at hour 3, and then increased gradually. However, Al uptake in NM roots increased with time. Foliar Al analysis indicated that Al concentration increased with time in both M and NM plants, but a significant increase of foliar Al concentration during the first 3-h period was not observed in M plants. The results suggested that the rate of Al transport and the redistribution of foliar Al were different in M and NM plants. The higher Al concentration in M roots may be due to the higher CEC in M roots and vice versa. Further, the CEC of M roots was decreased by the respiration inhibitor (CN-) treatment while the CEC of NM roots was not, suggesting that CEC in M roots is related to respiration.

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Janet F. M. Rippy, Paul V. Nelson, and Ted Bilderback

Problems of inconsistent initial pH in peat moss-based substrates that are created using standard formulas for limestone additions, and pH drift from the target in those substrates may be due to variations in the CEC and BS of peat moss. This study was conducted to determine whether such variation exists. Sixty-four peat moss samples were obtained from several bogs across Alberta, Canada. Adsorbed cations on each peat moss sample were displaced with hydrochloric acid (HCl), and flushed out with three deionized water washes. The displacing/flushing solution was collected and later analyzed for concentration of bases (Ca, Mg, K, and Na) using atomic absorption spectrometry. After cations were removed, the peat moss exchange sites were saturated with barium acetate [Ba(OAc)2] to displace the H+, which were then collected by a second flushing with deionized water. This second displacing/flushing solution was titrated with measured amounts of NaOH to a phenolphthalein end point. Base saturation and CEC were calculated. There were significant variations in CEC (ranging from 108.12 to 162.25 cmol·kg-1) and BS (ranging from 13.52% to 63.97% of CEC) among the peat moss samples. Ca accounted for 78.08% of the BS. For a given peat moss, the higher the BS, the lower the neutralization requirement to achieve a target pH. Also, high CEC peat mosses may have greater buffering capacity than those with low CEC, which may result in less pH drift.

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Michael R. Evans, Brian E. Jackson, Michael Popp, and Sammy Sadaka

an alkaline pH. The pH of the biochar products ranged from 4.6 for pine shavings to 9.3 for miscanthus. Table 3. The pH, electrical conductivity (EC), cation-exchange-capacity (CEC), and water-extractable primary macroelement concentration from

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Linda L. Taylor, Alexander X. Niemiera, Robert D. Wright, and J. Roger Harris

lamps from 0600 hr to 2000 hr daily. Cation exchange capacity, carbon-to-nitrogen ratio, particle size distribution, and bulk density. Cation exchange capacity, C:N ratio, particle size distribution, and BD were determined for five treatments: non

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J.L. NUS and S.E. Brauen

In a field experiment, clinoptilolitic zeolite was compared to sphagnum peat and sawdust as sand amendments at 5%, 10%, and 209” (v/v) to enhance `Penncross' creeping bentgrass (Agrostis palustris Huds.) establishment and to compare their gravimetric and volumetric cation exchange capacities and their effects on moisture retention and cation exchange capacities of the resultant mixes. In addition, cation exchange capacities and exchangeable K+ and \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{NH}_{4}^{+}\) \end{document}; were analyzed from clinoptilolitic zeolite of particle sizes ranging from <0.25 mm to >5.0 mm. All amendments, except 10?ZO and 20% sawdust, resulted in superior establishment compared to unamended sand. Peat-amended sand retained significantly more moisture than sawdust- or zeolite-amended sand at –6, –10, –33, and -250 kpa soil matric potentials. Zeolite exhibited a much higher volumetric cation exchange capacity than either sawdust or sphagnum peat. Cation exchange capacity and exchangeable potassium of clinoptilolitic zeolite was greatest when particle size was <0.5 mm; however, little exchangeable ammonium nitrogen was detected.

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James E. Ells, Ann E. MeSay, and Stephen M. Workman

Chopped alfalfa (Medicago sativa L.), alfalfa hay extract, and ammonium hydroxide produced free ammonia in media and inhibited both germination and seedling growth of cucumber (Cucumis sativus L.). Toxic levels of ammonia were not produced by the quantities of manure added to the media. Alfalfa extract enhanced cucumber seedling growth in sand medium while inhibiting growth in sand-soil media. This difference is attributed to a reduced level of microbial activity in the sand. With higher levels of microbial activity, rapid decomposition of the extract may have resulted in a burst of ammonia evolution that proved damaging to cucumbers. The natural buffering capacity of the soil medium apparently mitigated the effects of the ammonia. Ammonium hydroxide, which did not depend on microbiological activity to release ammonia, proved lethal to cucumbers grown in sand. A diminished effect on growth was observed as the cation exchange capacity of the medium increased. Because high levels of alfalfa hay and ammonium hydroxide were required to produce toxic levels of ammonia in soil, it is unlikely that cucumbers would be harmed under normal field usage of alfalfa hay.

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Richard C. Funt, Mark C. Schmittgen, and Glen O. Schwab

The performance of peach trees [Prunus persica (L.) Batsch cv. Redhaven/Siberian C.] on raised beds as compared to the conventional flat (unraised) orchard floor surface was evaluated from 1982 to 1991. The raised bed was similar to the flat bed in cation exchange capacity (CEC), Ca, P, K, Mg, B, and Zn soil levels in the 0-15 cm depth. Microirrigation, using two 3.7 L.h-1 emitters per tree vs. no irrigation, was applied to trees planted in a north-south orientation on a silt loam, noncalcareous soil. Raised beds increased trunk cross-sectional area (TCA) and yield-efficiency over 5 years. Irrigation increased fruit mass mostly in years of highest evaporation. Significant year to year variations occurred in yield, fruit mass, TCA and yield efficiency. There were significant bed × year interactions for yield and TCA. Irrigation increased leaf boron content regardless of bed type. Leaf potassium was higher in flat beds. Nonirrigated trees had the lowest tree survival on the flat bed, but the opposite was true on the raised bed.