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... Alfalfa seed contains a high percentage of impermeable seeds. After the first freezing, subsequent freezing and thawing seem to have very little influence in reducing the number of impermeable alfalfa seeds. The first freezing is by far the most effective. It reduced the number of impermeable seeds about 23%, on the average. The intensity of freezing has no influence in reducing the impermeability ...
... This study was made as a preliminary investigation to determine whether certain procedures might be of use in making studies of soil structure. The Bouyoucos method of measuring soil permeability to water seems satisfactory as a percolation method. The method is sufficiently sensitive to distinguish soil types that show marked differences in behavior in the field, and to distinguish between surfac ...
... Wide cotton sheets were placed in service and laundered weekly. Chemical and physical tests were made on the sheets at successive wear intervals. The physical properties of the sheets, namely, strength, weight, thickness and air permeability, were found to be more adversely affected in the area exposed to the greatest wear. Copper number and alpha-cellulose determinations showed the chemical deter ...
... SummaryCalculations have been made of mean effective pore diameters based on the fractional open area and water permeability in six columns of different, laboratory-packed, water-saturated soils. The magnitudes of the pore diameters are associated with the occurrences of particle migration, but are unrelated to the absolute amounts of the latter, which have been measured by means of mechanical ana ...
... Summary and ConclusionsElectrodialyzed bentonite suspensions were treated with FeCl₃ in quantities from 12.5 to 250 per cent of the adsorption capacity. They were washed until no Cl⁻ appeared in the washing and several physico-chemical properties of the Fe clays were studied. Some of the more important data are summarized below. The Fe was about all adsorbed from additions of FeCl₃ up to 2.5 symme ...
... SummaryThe addition of lime to Cecil clay under field conditions reduced the permeability and had a dispersing effect on the soil aggregates. It would be expected to increase the susceptibility of the soil to erosion. Applications of organic matter up to four tons per acre had little effect on porosity after six months and no significant effect on aggregation or permeability after eighteen months. ...
... In this paper is described the derivation of the empirical relationship between two commonly used instruments for determining air permeability—namely, the Frazier and Gurley machines. In addition, the limitations of each of the devices are discussed as well as the number of specimens necessary for testing. The correlation has also been determined by consideration of physical constants and pressure ...
... An instrument to measure the air permeability of compressed fiber wads is described, together with essential details of construction. An index, F, of fiber fineness is defined follow ing the derivation of an approximate permeability. The roles played by porosity of the plug, the size, shape, and density of the fibers, and their effect on the values of F are discussed with reference to cotton. Erro ...
... This is the first in a series of papers to be issued by the Quartermaster Corps discussing the importance of fabric geometry in the development of more utilitarian and serviceable textile materials. It is a literature review which shows the relationship between the structural char acteristics of fabrics and various functional characteristics, such as breaking strength and elongation, tear-resistan ...
... A modified method for evaluating the distribution of pore spaces within a textile fabric, based on the principle outlined in the preceding paper in this series [1], is described. Data are reported for 14 tight fabrics, 6 of which had been treated with a water-repellent finish. The porosities of these fabrics are compared with the results of air- and hydrostatic-permeability measurements. ...
... Crimson clover plants were selected on the basis of permeability and inbred for three years. Parental selections in the S2 and S3 generations were confined almost exclusively within the originally established lines. In the first generation selfed parents differing 60.3% in permeability produced progeny differing by only 0.3%. S2 parents differing 44.8% in permeability yielded progeny with only a 3 ...
equations; irrigation; irrigation water; permeability; soil water; soil water content; water content
Abstract:
... Conclusions and SummaryIt was assumed when this problem was undertaken that there existed a function f of the moisture content that could be multiplied by the permeability constant k of the Darcy equation to make it applicable to movement of moisture in unsaturated soil. It would appear, however, from the experimental data obtained for a typical soil, that in addition to a pressure gradient due to ...
... Field clues to soil permeability were investigated at 182 locations from 1947 through 1951. Estimates of permeability were made in the field without prior knowledge of measured percolation rates. Then the estimated permeability class was compared with the measured rate. In case of discrepancy, the profile was re-examined to see if any signfiicant clues had been overlooked. It was found that permea ...
... The purpose of this study was to determine some changes that have taken place in the surface of cultivated soils. Permeability, volume weight, and percent of pores drained were determined on virgin soils, fertilized and unfertilized soils, soil farmed to a good rotation in contrast to a poor rotation, and eroded soils as compared to slightly eroded soils. Some studies were also made on the effect ...