Soil Science Society of America Journal
1435-0661
0361-5995
Mỹ
Cơ quản chủ quản: WILEY , John Wiley & Sons Inc.
Lĩnh vực:
Soil Science
Các bài báo tiêu biểu
Speciation and Distribution of Phosphorus in a Fertilized Soil Phosphorus availability is often a limiting factor for crop production around the world. The efficiency of P fertilizers in calcareous soils is limited by reactions that decrease P availability; however, fluid fertilizers have recently been shown, in highly calcareous soils of southern Australia, to be more efficient for crop (wheat [Triticum aestivum L.]) P nutrition than granular products. To elucidate the mechanisms responsible for this differential response, an isotopic dilution technique (E value) coupled with a synchrotron‐based spectroscopic investigation were used to assess the reaction products of a granular (monoammonium phosphate, MAP) and a fluid P (technical‐grade monoammonium phosphate, TG‐MAP) fertilizer in a highly calcareous soil. The isotopic exchangeability of P from the fluid fertilizer, measured with the E‐value technique, was higher than that of the granular product. The spatially resolved spectroscopic investigation, performed using nano x‐ray fluorescence and nano x‐ray absorption near‐edge structure (n‐XANES), showed that P is heterogeneously distributed in soil and that, at least in this highly calcareous soil, it is invariably associated with Ca rather than Fe at the nanoscale. “Bulk” XANES spectroscopy revealed that, in the soil surrounding fertilizer granules, P precipitation in the form of octacalcium phosphate and apatite‐like compounds is the dominant mechanism responsible for decreases in P exchangeability. This process was less prominent when the fluid P fertilizer was applied to the soil.
Tập 70 Số 6 - Trang 2038-2048 - 2006
Designs for Disc Permeameters Abstract Disc permeameters are designed to measure hydraulic properties of field soils containing macropores and preferential flow paths and are particularly useful in soil management studies. We present here designs for disc permeameters for both positive and negative water supply heads. The effects of the water supply membrane and soil contact material on permeameter performance are examined using approximate quasi‐analytic solutions to the flow equation. This analysis provides approximate criteria for the selection of membrane and soil contact materials. Limitations to performance caused by restricted air entry are considered and design criteria are given also. We present in situ tests of the disc permeameter for the early stages of one‐dimensional infiltration and an example of the deterministic variation of sorptivity of a field soil with supply potential. Finally, we use ponded and unsaturated sorptivities measured in situ with disc permeameters to find the saturated hydraulic conductivity and flow‐weighted mean characteristic pore dimension of a field soil.
Tập 52 Số 5 - Trang 1205-1215 - 1988
Effect of Water Regime on Aggregate-tensile Strength, Rupture Energy, and Friability
Tập 66 Số 3 - Trang 702 - 2002
Transient Flow from Tension Infiltrometers I. The Two‐Parameter Equation Tension disk infiltrometer experiments are generally conducted until apparent steady state is reached because most of the methods of analysis are based on Wooding's solution for steady state flux. However, the time necessary to reach steady state may be a penalizing aspect for soils with low permeability and the information contained in the transient stages is not utilized. Moreover, these methods assume homogeneous soil and a uniform initial water content, which may be unrealistic when a large volume of soil is sampled. In this series, we propose and compare several new methods of analysis that are based on the transient stage of axisymmetric infiltration. In the first part, we show that a two‐parameter equation—one term linear in square root of time and one term linear in time—adequately describes the transient flow from the disk infiltrometer for both simulated and laboratory tests. The technique used for the determination of the two coefficients must meet two criteria; it must verify the validity of the two‐term equation throughout the duration of the experiment, and it must account for the early‐time perturbation that is induced by the sand‐contact layer placed between the disk and the soil. We show that the best technique consists in linearizing the data by differentiating cumulative infiltration with respect to the square root of time. Direct nonlinear fitting on cumulative infiltration or infiltration flux is likely to lead to unacceptable errors, either because of the undetected invalidity of the two‐parameter equation or arising from the influence of the contact layer.
Tập 64 Số 4 - Trang 1263-1272 - 2000
Factors Controlling Soil Organic Carbon Stocks with Depth in Eastern Australia
Tập 79 Số 6 - Trang 1741-1751 - 2015
Genesis of Argillic Horizons in Soils Derived from Coarse‐textured Calcareous Gravels Abstract Soils with fine‐textured argillic horizons overlying calcareous gravel are of widespread occurrence on terraces, kames, and eskers in Ohio. The objective of this study was to determine if the argillic horizon in these soils, generally containing 25–50% clay, could develop from a calcareous gravelly deposit containing < 10% clay. Two pairs of sites were chosen, one pair developed on gravel material containing 60% carbonates, the other pair on gravel containing 40% carbonates. One member of each pair occurred on a terrace whereas the other occurred on a kame. A reconstruction technique utilizing Ti and Zr contents of the soil fraction >2 µm was used to calculate the gains and losses of various constituents in the solum relative to the parent material. The residue remaining after acid dissolution of carbonates was determined for gravel, sand, and silt fractions. The carbonate content of the C horizons ranged from as high as 90% in the 16–32 mm fraction to < 5% in the clay fraction. Dissolution of carbonates and addition of clay residue from the carbonate rocks decreased the gravel content from 75 to 52% and increased the clay content from 1.4 to 10.3%. A calculation of gains and losses for weathered solum shows substantial gains of clay, silt, and sand which is balanced by a loss of gravel. It has been proposed that the gain in sand, silt, and clay is a result of disintegration of shale, siltstone, sandstone, and crystalline lithics in the sand and gravel fractions. It is therefore concluded that fine‐textured B horizons could develop from coarse‐textured calcareous gravelly outwash.
Tập 40 Số 5 - Trang 739-744 - 1976
A Technique for Rapid Removal of Gypsum from Soil Samples Abstract Removal of gypsum from soil samples is necessary to disperse soils for particle‐size analysis or clay separation for mineralogical study. A technique utilizing the heating of gypsiferous soil overnight at 105°C is presented. The heat treatment converts gypsum to bassanite which is more soluble than the gypsum and the disruption of the gypsum upon dehydration also yields bassanite particles which can easily be crushed to provide a greater surface area. Subsequently, the time required to remove gypsum from soil by dialysis is reduced by >50%. Heating the samples did not change the clay mineralogy or the cation exchange capacity, but did result in slightly higher total and fine clays and slightly lower sand contents.
Tập 46 Số 6 - Trang 1338-1340 - 1982
Genesis of Argillic Horizons in Soils of Desert Areas of the Southwestern United States Abstract We studied soils and landscapes in the southwestern part of the Lake Lahontan drainage basin in Nevada and soils on alluvial fans near Phoenix and Willcox, Arizona and Mojave, California. The youngest surface is less than 12,000 YBP (years before present), the oldest is pre‐Wisconsin in age. Typic Torripsamments are on surfaces younger than 12,000 YBP, finer textured Haplargids and Paleargids are on surfaces older than 12,000 YBP. The volume of clay skins in a sandy family of Xeralfic Haplargids on a late Wisconsin age, dune‐sand surface is approximately equal to the increase of clay in its B horizon, whereas clay skins are mostly lacking in the fine‐textured Haplargids and Paleargids formed in sandy alluvium. Both the distribution of quartz and total silica in the sand + silt and the distribution of volcanic fragments in the very fine sand show that the A horizons of the finer textured Haplargids and the Paleargid are as weathered as, or more weathered, than their B horizons. This is evidence that the B horizons of Argids were formed at least in part by translocation of clay. Accumulation of total Al2 O3 and Fe2 O3 in these argillic horizons is more direct evidence that clay translocation occurred. The older Argids have clay maxima below the calculated depth of wetting in most years. These clay maxima are near the depth of wetting expected once or twice each 100 years in the older Argids, but the present climate does not seem adequate to have produced the soils in the time involved. Rather these older Argids are probably products of moister Plestocene climates.
Tập 39 Số 5 - Trang 919-926 - 1975