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1. |
ADSORPTION‐DESORPTION OF POTASSIUM AND AMMONIUM AT LOW CATION CONCENTRATIONS IN THREE KENTUCKY SUBSOILS |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 269-278
J. LUMBANRAJA,
V. EVANGELOU,
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摘要:
The presence of surface competing cations and pH are expected to have an influence on the cation adsorption-desorption behavior of soils. In this study, we evaluated the adsorption-desorption behavior of K+in the presence of solution Ca2+(binary) or in the presence of solution Ca2+plus NH4(ternary) and the adsorption-desorption behavior of NH+4in the presence of solution Ca2+(binary) or in the presence of solution Ca2+plus K+(ternary). The soils selected for the study were the Eden, Lowell, and Nicholson soils from Northern Kentucky. These soils are generally known to give poor yield response to fertilizer application. It was shown that potassium adsorption was suppressed by solution NH+4while NH+4adsorption was greatly enhanced by solution K+. Adsorption of K+and NH+4also increased as pH increased. Ammonium desorption, on the other hand, decreased in the presence of solution K+relative to that in the absence of solution K+, increased at the medium pH tested, but decreased at the highest pH tested. Furthermore, in general, fixation accounted for most of the adsorbed K+or NH+4. The results suggested that-predicting exchange or apparent fixation behavior of monovalent cations based on ion size and charge for soils containing vermiculite type minerals is difficult. Experimental exchange data are needed to make accurate binary or ternary cation exchange predictions in such soil systems
ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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2. |
METRIBUZIN MOBILITY AND DEGRADATION IN UNDISTURBED SOIL COLUMNS |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 279-288
MARTIN LOCKE,
SIDNEY HARPER,
LEWIS GASTON,
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摘要:
Metribuzin [4-amino-6-(1–1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] is a widely used soil-applied herbicide, and its dissipation was assessed using undisturbed soil columns to simulate field conditions. Metribuzin (technical grade and14C-labeled dissolved in 0.1MCaCl2) was applied to the soil (Dundee loam) surface at a concentration equivalent to 0.68 kg metribuzin ha−1. Water was added to the surface at 1, 8, 15, 22, 29, and 36 days after treatment. Chloride (Cl−) and14C were measured in the effluent. Twenty-four hours after each leaching, three cores were randomly selected, sectioned at 0–3.3-, 3.3–6.6-, and 6.6–10-cm depth increments, and analyzed. Metribuzin mineralization was monitored weekly by trapping14CO2-C in 0.5MNaOH. The pattern of Cl−appearance in the effluent indicated possible preferential flow. Metribuzin degradation in the 10-cm profile followed first-order kinetics, with parent metribuzin being the dominant extractable species until the last 14 days when a composite of unidentified polar metabolites was prevalent. Metribuzin was the primary single component measured in the effluent until 37 days after application. However, from 9 days after herbicide application through the remainder of the experiment, the fraction of total applied14C present as metabolites (summation of known metabolites diketometribuzin [DK], deaminated metribuzin [DA], and deaminated diketometribuzin [DADR] and unidentified polar metabolites) exceeded metribuzin in the effluent. As an average over time, the 3.3–6.6-cm section contained the most methanol unextractable14C
ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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3. |
ENVIRONMENTAL IMPACTS OF NITRIFICATION AND NITRATE ADSORPTION IN FERTILIZED ANDISOLS IN THE VALLE CENTRAL OF COSTA RICA |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 289-299
J. REYNOLDS-VARGAS,
D. RICHTER,
E. BORNEMISZA,
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摘要:
A major scientific challenge for modern agriculture is control of off-site effects on the water resource. In the Valle Central of Costa Rica, coffee plantations may leach fertilizer-derived NO−3to groundwaters, as a result of high fertilization rates (annually ∼270 kg/ha as N), highly permeable and well structured Andisols, and high rates of annual runoff (>1000 mm). The objective of this study was to examine several aspects of the nitrification and NO−3adsorption that control NO−3leaching from these highly productive soils. Monthly collections from four Andisols indicated that soil NO−3varied seasonally, with NO−3accumulating to about 280 kg/ha in the upper meter of soil during the 5-month dry season. Soil NO−3was reduced during wet season months, even though fertilization was confined to the wet season. During these months, soil NO−3averaged about 140 kg/ha as N in the upper meter of soil, apparently reduced by wet season leaching, root uptake, and, possibly, dentrification. Field and laboratory incubations at different soil moisture and temperature regimes demonstrated how soil microflora mineralized N and nitrified NH+4at relatively high rates, even at low water potentials, e.g.,−3can be adsorbed by these allophanous Andisols, especially at low pH (up to about 5 cmol/kg at pH−3to groundwater; however, the effectiveness of adsorption as a protection of groundwater quality is probably limited due to high inputs of fertilizer N and to liming management of coffee soils that maintains relatively high soil pH. Additional research into the coffee N cycle and fertilizer efficiency in coffee is needed to ensure high coffee productivity and to protect aquifer water quality in the Valle Central
ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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4. |
SPECTROSCOPIC PEAT CLASSIFICATION AND CALIBRATION USING ELECTRON SPIN RESONANCE AND MULTIVARIATE DATA ANALYSIS |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 300-311
HANS KARLSTRÖM,
B NORDÉN,
GÖRAN WIKANDER,
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摘要:
Electron Spin Resonance (ESR) measurements were performed on particle size fractions of high and low humifiedSphagnum fuscumandCarex rostrata. Each peat sample was divided into seven particle size groups, where the size varies between >2.0 andCarexpeat type class and the low humifiedSphagnumpeat, slightly worse with the high humifiedCarexpeat and the high humifiedSphagnumpeat types. Many of the dependent variables were well modeled, and unknown test samples were correctly predicted
ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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5. |
MORPHOLOGIC AND COLOR PATTERN INDICATORS OF WATER TABLE LEVELS IN SANDY PINELANDS SOILS |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 312-317
ROBERT ZAMPELLA,
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摘要:
Growing season (March-October) water table levels were measured over a 4-year period, and soil profiles were described along a gradient of upland to wetland pitch pine-dominated sites in the New Jersey Pinelands. These sites were associated with very poorly to somewhat poorly drained soils of the Lakewood sand catena. Although several profile attributes were more closely associated with specific ranges of water table levels, few features were, limited to a specific hydrologic regime. O and A horizon thickness and frequency of very dark gray to black A horizons generally decreased along the wet to dry hydrosequence. E horizon thickness was variable and unrelated to water table level. Bh horizons with values and chromas of 2 or 3 characterized soils with first quartile water tables from 15.1 to 60 cm from the surface. Chromas of 1–4 dominated all but the driest soils. Relatively bright high chroma, horizons, with or without low chroma mottling (chromas ≤ 2), were most common in soils with first quartile water levels greater than 45 cm from the surface, yet they also occurred in some of the most frequently saturated soils. In most cases, low chroma mottles as well as the lower surface of high chroma horizons without mottling were found at or below the highest water level recorded during the study period. These results suggest that soil features are not absolute indicators of water table level in somewhat poorly drained and very poorly drained soils of the Lakewood catena. A dual parameter approach that considers both soil features and vegetation to determine water levels provides a more accurate estimate of hydrologic conditions in these soils. Estimates based on one parameter should not be discounted when that parameter clearly characterizes hydrologic regime
ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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6. |
QUANTIFYING THE CHANGES IN CLAY STABILIZATION AFTER THE INTRODUCTION OF FORAGES |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 318-327
V. RASIAH,
B. KAY,
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摘要:
The objectives of this study were to (i) develop a semiempirical model to predict the changes in clay stabilization after the introduction of forages, (ii) assess the model using data from different soils, and (iii) determine the influence of soil properties on clay stabilization. Dispersible clay (DC) measurements were made at monthly intervals during the 1989, 1990, and 1991 growing seasons on seven soils under continuous conventionally tilled corn and forage treatments established in 1989. The influence of cropping treatment, time of sampling, water content (Θ) at sampling, and the interaction of these terms onDCwas significant for each soil atP= 0.05. Using the variation inDCwith Θ over time, a semi-empirical model was developed to predict the changes in the amount of clay stabilized by forages. The model parameters described (i) the rate at which clay stabilization occurred and (ii) the maximum potential amount of clay stabilized. The rate was characterized by half-life (t1/2) for the stabilization process. TheR2for the best fit of the model ranged from .48 to .84, and the fit was significant for each soil atP= 0.05. The projectedt1/2for clay stabilization ranged from 3.55 to 9.12 years. The maximum potential amount of clay stabilized ranged from 0.55 to 4.51%. Thet1/2decreased with increasing clay and organic matter contents and pH, whereas an opposite trend was observed for the maximum potential amount of clay stabilized. The model provided a framework for assessing the influence of changes in cropping practices and soil properties on clay stabilization
ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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7. |
Soil Biochemistry |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 328-328
J.-M. Bollag,
G. Stotzky,
ROBERT TALE,
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ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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8. |
Farm Land Erosion |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 329-329
S. Wicherek,
HAROLD ECK,
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ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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9. |
Principles of soil Chemistry |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 330-330
Kim Tan,
RICHMOND BARTLETT,
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ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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10. |
Iron Chelation in Plants and Soil Microorganisms |
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Soil Science,
Volume 157,
Issue 5,
1994,
Page 331-332
Larry Arton,
Bruce Hemming,
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ISSN:0038-075X
出版商:OVID
年代:1994
数据来源: OVID
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