Showing papers in "Soil Science in 1965"
1,010 citations
TL;DR: In this article, the authors show that surface moisture content, organic matter, and particle size strongly influence the reflectance and absorptance of solar radiant energy by soils, and apply the kaolinite reflectance data to Gates' direct solar energy distribution curve, one would expect energy absorption to increase by at least an additional 14.6 percent of that in the incident beam when the particle size is increased from 22 mu to 2650 mu.
Abstract: Data secured with spectrophotometers show that surface moisture content, organic matter, and particle size strongly influence the reflectance and absorptance of solar radiant energy by soils. At all wavelengths measured, on all samples, reflectance decreased and absorptance increased as moisture content increased. By using Gates' direct solar energy distribution curve, one would expect that increasing the moisture content on a Newtonia silt loam from 0.8 to 20.2 percent would increase absorption of radiant energies by at least 14.2 percent of that in the equivalent direct solar beam. The plot of moisture content against reflectance indicates the possibility of using reflectance methods for surface moisture determinations. Results were especially good at 1900 mu, a moisture-sensitive wavelength. The oxidation of soil organic matter increased the reflectance from all samples measured. Again using Gates' distribution curve, 8.2 percent more of the energy in the equivalent direct solar beam might have been reflected by the oxidized Newtonia silt loam sample. With both kaolinite and bentonite clays, reflectance increased exponentially as particle size decreased. The magnitude of reflectance change was very similar with both clays. By applying the kaolinite reflectance data to Gates' direct solar energy distribution curve, one would expect energy absorption to increase by at least an additional 14.6 percent of that in the incident beam when the particle size is increased from 22 mu to 2650 mu. /Author/
642 citations
TL;DR: The surface area is a fundamental property of layer silicates, and it has been used as a criterion for identification as mentioned in this paper, although it is not an equilibrium method, much useful information has been provided by its use.
Abstract: Total surface area is a fundamental property
of layer silicates, and it has been used as a criterion
for identification. Early methods for determining
surface area used nitrogen or ethane
gas and were based on the principle that solid
materials will adsorb a monomolecular layer of
the gas at a particular pressure (4, 6). Dyal and
Hendricks (6) introduced a method for determining
surface area with ethylene glycol. Their
method has been adapted to determining surface
area of soils and soil minerals (2) and, although
it is not an equilibrium method, much useful
information has been provided by its use.
380 citations
TL;DR: Barbela et al. as discussed by the authors presented a Flask and method for measuring the persistence and biological effects of pesticides in the soil, and used it to measure the effect of pesticides.
Abstract: Features of a Flask and Method for Measuring the Persistence and Biological Effects of Pesticides in Soil RICHARD BARTHA;DAVID PRAMER; Soil Science
368 citations
248 citations
TL;DR: Bower and Goertzen as discussed by the authors proposed a modification of the Dyal and Hendricks method for measuring surface area of layer silicates, which is considered to be an equilibrium-based method.
Abstract: Total surface area is an important fundamental
soil property. This property is measured
to estimate the proportion of lattice expandable
layer silicates in soils and to assess soil physical
and chemical properties. Dyal and Hendricks
(4) introduced a method for measuring surface
area of layer silicates. This method was modified
and adapted to soils by Bower and
Gschwend (1). Subsequently, Martin (5) proposed
a modification of the Dyal and Hendricks
method (4) for layer silicates. His modification
included a source of free ethylene glycol in the
evacuated desiccator to control the vapor pressure
of ethylene glycol at the mineral sorption
surfaces. Bower and Goertzen (2) modified the
method proposed by Martin (5) and adapted it
for measuring soil surface area. This latter
method is considered to be an equilibrium
method (2) and is widely used today. A similar
but more complex method was introduced by
Sor and Kemper (7). All these methods utilize
ethylene glycol, a highly polar molecule, as the
absorbed phase. They all have the common disadvantage
of being very time-consuming.
237 citations
192 citations
TL;DR: In this paper, it was found that the HYDRAULIC CONDUCTIVITY of different types of PEAT have different characteristics, such as dense, decomposed, and herbaceous PEAT.
Abstract: AN ANALYSIS OF THE DATA COLLECTED REVEALED THAT FIELD- MEASURED HYDRAULIC CONDUCTIVITIES OF PEATS WERE SIGNIFICANTLY LOWER THAN CORRESPONDING LABORATORY VALUES. IT WAS ASSUMED THE FIELD-MEASURED VALUE WOULD MORE ACCURATELY REPRESENT THE HYDRAULIC CONDUCTIVITY OF ORGANIC SOILS. FURTHER ANALYSIS INDICATED NO SIGNIFICANT DIFFERENCE BETWEEN VERTICAL AND HORIZONTAL HYDRAULIC CONDUCTIVITY AS MEASURED, RESPECTIVELY, BY THE TUBE AND PIEZOMETER METHODS. THEREFORE, THE PIEZOMETER FIELD METHOD WAS SELECTED FOR USE IN DETERMINING THE HYDRAULIC CONDUCTIVITY OF DIFFERENT TYPES OF PEAT. HYDRAULIC CONDUCTIVITIES OF PEAT TYPES WERE FOUND TO COVER A WIDE RANGE OF VALUES. THE VALUES ARE RELATED TO SPECIFIC YIELD AND, THEREFORE, PROBABLY TO PORE-SIZE DISTRIBUTION. UNDECOMPOSED MOSS PEATS IN OR NEAR SURFACE HORIZONS HAVE MANY LARGE PORES THAT ARE EASILY DRAINED. THEY HAVE HIGH SPECIFIC YIELDS AND ALLOW RAPID WATER MOVEMENT, HAVING GREAT HYDRAULIC CONDUCTIVITY. WOODY PEATS AND DEEP UNDECOMPOSED MOSS PEAT HAVE HYDRAULIC CONDUCTIVITY RATES COMPARABLE TO SANDY LOAMS AND FINE SANDS. MORE DENSE, DECOMPOSED, AND HERBACEOUS PEATS PERMIT LITTLE WATER MOVEMENT, WITH CONDUCTIVITY RATES LOWER THAN MANY GLACIAL TILL SOILS. THESE PEATS HAVE MANY SMALL PORES, WHICH ARE NOT EASILY DRAINED AND WHICH DEMONSTRATE LOW SPECIFIC YIELDS.
190 citations
TL;DR: In this article, the authors proposed the designation "K horizon" for soil horizons so strongly carbonate-impregnated that their morphology is determined by the carbonate, and the designation K2 is proposed for carbonate horizons of 90 percent or more, by volume, of K-fabric.
Abstract: The designation "K horizon" is proposed for soil horizons so strongly carbonate-impregnated that their morphology is determined by the carbonate. Tough these horizons display a variety of macroscopic forms, and range in consistence from soft to extremely hard, they all have a peculiar and diagnostic soil fabric, the K-fabric. In material with K-fabric, fine-grained authigenic carbonate coats or engulfs skeletal pebbles, sand, and silt grains as an essentially continuous medium. The material breaks down or is markedly softened by acid treatment. The designation K2 is proposed for carbonate horizons of 90 percent or more, by volume, of K-fabric, and K1 and K3 designations are proposed for upper and lower transitional horizons containing 50 percent or more of K-fabric. Other soil horizons containing carbonate accumulations are noted by the ca symbol in combination with the appropriate master horizon designation. /Author/
183 citations
TL;DR: In this article, a thermal gradient in soil will cause water to move from a warm to a cooler area in both the liquid and vapor phases, and the rate of transfer is greater than can be predicted with Lick's law and the diffusion coefficient for water vapor into air.
Abstract: That thermal gradients cause moisture transport
in soil has been well known for at least 50
years. It is, however, surprising that so little attention
has been paid to this phenomenon, since
soil in its natural environment is continuously
subject to changing temperatures. In 1957 Philip
and de Vries (14) published a theoretical article
in which they attempted to reconcile the few
existing experimental data. Since then, alternative
approaches have been suggested by Derjaguin
and Melnikova (5), Matthes and Bowen
(12), and Taylor and Cary (16). The experimental
observations available are, however, insufficient
to make a fair test of any of the proposed
theories. As a general statement, about all
that can be said is: A thermal gradient in soil will
cause water to move from a warm to a cooler
area in both the liquid and vapor phases, and
the rate of transfer is greater than can be predicted
with Lick's law and the diffusion coefficient
for water vapor into air.
The experiment reported in this article was designed
to yield data defining the relative importance
of thermal gradients in transporting
soil moisture and to probe the mechanisms of
transfer.
TL;DR: In this article, a mathematical expression for the permanent protection or improvement of soil resources in accordance with measurable standards, and, by assumption, for the fractional utilization of soil property reserves when needed.
Abstract: At least as early as 1620, American farmers and patriots recognized water erosion as a problem and attempted to develop practical ways to protect their soil (35). During the first two decades of the 20th century the seriousness of erosion was indicated by a number of agricultural leaders (3, 33). Following the publication of significant research findings regarding erosion in Missouri (37) and Texas (12), and an educational campaign by the United States Department of Agriculture under the leadership of H. H. Bennett, the House of Representatives passed the Buchanan Amendment to the Agricultural Appropriation Bill for the fiscal year 1930, appropriating $160,000 for investigations of causes of soil erosion and methods for its control (3). This legislation marked the beginning of a vigorous and expanding program, the course of which is known to farmers and the general public throughout much of the world (3). In order to measure soil conservation progress and to plan most effectively for the future, it is important to establish a common understanding of basic definitions and assumptions. Therefore a mathematical expression has been developed (53) that provides, by definition, for the permanent protection or improvement of soil resources in accordance with measurable standards, and, by assumption, for the fractional utilization of soil property reserves when needed. Net change from present condition is stated by a definite integral involving soil erosion and soil renewal (or addition) rates with time. The information needed for the solution of this "erosion tolerance equationJ' is: (a) specific inventory of present soil resources, ( b ) expression of essential soil property requirements for the future, ( c ) data on erosion (or