Soil Particle Size Distribution Protocol

The purpose of this resource is to sure the distribution of different sizes of soil particles in each horizon of a soil profile. Using dry, sieved soil from a horizon, students mix the soil with water and a dispersing solution to completely separate the particles from each other. Students shake the mixture to fully suspend the soil in the water. The soil particles are then allowed to settle out of suspension, and the specific gravity and temperature of the suspension are measured using a hydrometer and thermometer. These measurements are taken after 2 minutes and 24 hours. Educational levels: Middle school, High school

Estimation of Apollo lunar dust transport using optical extinction measurements

A technique to estimate mass erosion rate of surface soil during landing of the Apollo Lunar Module (LM) and total mass ejected due to the rocket plume interaction is proposed and tested. The erosion rate is proportional to the product of the second moment of the lofted particle size distribution N(D), and third moment of the normalized soil size distribution S(D), divided by the integral of S(D)D^2/v(D), where D is particle diameter and v(D) is the vertical component of particle velocity. The second moment of N(D) is estimated by optical extinction analysis of the Apollo cockpit video. Because of the similarity between mass erosion rate of soil as measured by optical extinction and rainfall rate as measured by radar reflectivity, traditional NWS radar/rainfall correlation methodology can be applied to the lunar soil case where various S(D) models are assumed corresponding to specific lunar sites.Comment: Acta Geophysica 201

Effects of grain size distribution on the initial strain shear modulus of calcareous sand

The soil’s small strain shear modulus, Gmax or G0, is applied in dynamic behavior analyses and is correlated to other soil properties (density and void ratio) for predicting soil dynamic behavior under seismic loadings such as earthquakes, machinery or traffic vibrations. However, for calcareous sands, selecting representative samples for the field conditions is difficult; therefore, almost all measured soil parameters (post-seismic properties) do not reflect exactly the soil state before seismic loading. In some cases of dynamic loading, a change in grain size distribution (GSD) of soils, especially for calcareous sands might occur. Moreover, many of these sand types behave differently from silica sands owing to their mineralogy, particle characterization, soil skeleton, and the continuous changing of particle size. For this reason, a series of isotropic consolidation tests in ranges of confining pressure from 25 to 300 kPa as well as bender element measurements on a calcareous sand and on a reference silica sand were performed in this study. The effects of differences in gradation and in the type of material on the soil’s small strain shear modulus, Gmax, are discussed

Effect of soil texture on the microwave emission from soils

The intensity brightness temperature of the microwave emission from the soil is determined primarily by its dielectric properties. The large difference between the dielectric constant of water and that of dry soil produces a strong dependence of the soil's dielectric constant on its moisture content. This dependence is effected by the texture of the soil because the water molecules close to the particle surface are tightly bound and do not contribute significantly to the dielectric properties. Since this surface area is a function of the particle size distribution (soil texture), being larger for clay soils with small particles, and smaller for sandy soils with larger particles; the dielectric properties will depend on soil texture. Laboratory measurements of the dielectric constant for soils are summarized. The dependence of the microwave emission on texture is demonstrated by measurements of brightness temperature from an aircraft platform for a wide range of soil textures. It is concluded that the effect of soil texture differences on the observed values can be normalized by expressing the soil moisture values as a percent field capacity for the soil

Does Wildfire and Cheatgrass Invasion in a Sage-steppe Ecosystem Change Soil Texture?

Fire and land-use changes influence vegetation types and alter below-ground carbon storage and soil characteristics; additionally, shrub-steppe environments are prone to cheatgrass invasion and subsequent alterations in soil morphology and characteristics following fire. We compared soil particle size, texture, consistence, structure, color and pH among adjacent but distinct sagebrush (Artemisia tridentata ssp.), cheatgrass (Bromus tectorum) and crested wheatgrass (Agropyron cristatum) communities established following a 1983 fire in Kuna Butte of southwestern Idaho, a site underlain by basalt and mantled with loess. Soil characteristics were compared in qualitative field soil profiles (two pits per vegetation type) and laboratory hydrometer analyses from paired sites in different vegetation types. Our data does not support differences in soil particle size (silt, clay, sand) among vegetation types; however, particle size and distribution varied with depth within a single soil pit. Field texture classifications and hydrometer results indicate silt-loam was the most common soil type. This study shows no substantive change in soil texture with change in vegetation type; similarities in soil textures could be due to 1) insufficient time for manifestation of soil development following fire and establishment of vegetation, 2) inadequate sampling and/or sample distribution, 3) minimal influence of vegetation type on underlying soil characteristics

The Characteristic of Soil Developed From Felsic Sediments in West Kalimantan Province and Its Implication to Land Manageme

Reconnaisance soil survey at 1:250.000 scale in West Kalimantan Province has been done covering 5.5 billion hectare. Result show that parent material governs formed soil properties. This research aimed to discuss soil properties developed from felsic sediment parent material in West Kalimantan Province and its implication to land management. As much as 100 pedons from felsic sediment parent material has been investigate in the field and in the laboratory for particle size distribution and chemical properties. Results show that particle size distribution or soil texture depend on parent material (sandstone, siltstone or claystone). Developed soil show acid soil reaction, ion organic material, ion P and K, ion exchangeable bases, ion base saturation, variable cation exchange capacity. Meanwhile, Al saturation is high and correlate positively with clay content. Soil properties that influence land management are particle size distribution and chemical properties. Land management showed be directed to increase soil pH, to decrease Al reactivity, to increase soil P and K, organic matter and exchangeable bases

Influence of particle size distribution on the blast pressure profile from explosives buried in saturated soils

The spatial and temporal distribution of pressure and impulse from explosives buried in saturated cohesive and cohesionless soils has been measured experimentally for the first time. Ten experiments have been conducted at quarter-scale, where localised pressure loading was measured using an array of 17 Hopkinson pressure bars. The blast pressure measurements are used in conjunction with high-speed video filmed at 100,000 fps to investigate in detail the physical processes occurring at the loaded face. Two coarse cohesionless soils and one fine cohesive soil were tested: a relatively uniform sand, a well-graded sandy-gravel, and a fine-grained clay. The results show that there is a single fundamental loading mechanism when explosives are detonated in saturated soil, invariant of particle size and soil cohesion. It is also shown that variability in localised loading is intrinsically linked to the particle size distribution of the surrounding soil

Particle-size characteristics of the vertical dust profiles of two contrasting dust events in the Channel Country of western Queensland, Australia

Spatial and temporal variations in vegetation and soil surface conditions of rangelands add a level of complexity to wind erosion processes which is often difficult to model or measure. Butler and colleagues have developed a methodology which combines computer simulation and experimental measurement to analyse how spatial and temporal changes in dust source area emission rates and atmospheric conditions affect vertical dust concentration profiles during wind erosion events in the Queensland Channel Country. This methodology has not, however, taken into account how variations in dust source area particle-size can affect vertical dust concentration profiles. The present paper examines how the particle-size characteristics of dust source soils affect both vertical dust concentration profiles and the vertical distribution of particle-sizes in two contrasting wind erosion events in the Queensland Channel Country. Comparisons are made between computer simulations of these events and the results of field measurements (of vertical dust concentration profiles) and laboratory measurements (of dust particle-size). Computer simulations of the particle-size emissions from the different dust source areas during the two events produce vertical distributions of dust particle-sizes which are similar to the measured dust particle-sizes for these events. These results indicate that erodibility-induced spatial and temporal variations in particle-size emissions of dust source areas have important influences upon: dust fluxes, vertical dust concentration profiles and the vertical distribution of dust particle-sizes within these profile

Rain water transport and storage in a model sandy soil with hydrogel particle additives

We study rain water infiltration and drainage in a dry model sandy soil with superabsorbent hydrogel particle additives by measuring the mass of retained water for non-ponding rainfall using a self-built 3D laboratory set-up. In the pure model sandy soil, the retained water curve measurements indicate that instead of a stable horizontal wetting front that grows downward uniformly, a narrow fingered flow forms under the top layer of water-saturated soil. This rain water channelization phenomenon not only further reduces the available rain water in the plant root zone, but also affects the efficiency of soil additives, such as superabsorbent hydrogel particles. Our studies show that the shape of the retained water curve for a soil packing with hydrogel particle additives strongly depends on the location and the concentration of the hydrogel particles in the model sandy soil. By carefully choosing the particle size and distribution methods, we may use the swollen hydrogel particles to modify the soil pore structure, to clog or extend the water channels in sandy soils, or to build water reservoirs in the plant root zone