Range Of Soil Properties Research Articles

Correspondence of Soil Properties and Classification Units with Sagebrush Communities in Southeastern Oregon: I. Comparisons between Mono‐taxa Soil‐vegetation Units

AbstractA preliminary second‐order soil survey (1:15840) of Squaw Butte Range Exp. Stn., Oregon, identified a single shallow upland soil that supported six contrasting sagebrush communities. Six delineations of this soil, each associated with different vegetation, were sampled intensively to objectively determine if soil properties and classification differed between delineations. Plant communities represented six different sagebrush (Artemisia) habitat types: A. longiloba/Agropyron spicatum, A. longiloba/(fescue) Festuca idahoensis, A. arbuscula/F. idahoensis, A. tridentata ssp. wyomingensis/A. spicatum, (F. idahoensis), and A. t. ssp. vaseyana/F. idahoensis‐A. spicatum. Morphological properties of profile samples were statistically compared by defining aggregate horizons (tiers) that were common to all profiles. Stepwise discriminant analysis selected elevation, aspect, presence of E and BA horizons, clay content of the Bt horizon, and sand content of surface strata as those which best distinguished between plant communities. Evidence suggests that series separations are justified based on family and class distinctions of higher categories or differences in range of soil properties, including variations in horizonation, volumetric rock fragment content of A and Bt horizons, and structure of BAt horizons. Phase separation criteria suggested include aspect, parent material, slope, and surface texture. Structure type of subhorizons, subhorizon position, and nutrient content are soil properties that may also provide important discrimination between soils possessing different range potentials.

A Zinc Soil Test Calibration Based upon Mehlich 3 Extractable Zinc, pH, and Cation Exchange Capacity

AbstractThe soil Zn critical level generally decreases as organic matter content increases. Certain other properties, notably cation exchange capacity (CEC) and optimum soil pH, also vary with organic content. These properties and Mehlich 3 extractable Zn (M3Zn) were used to calibrate a Zn soil test from greenhouse and field data. Soils were collected from four lime treatments in field experiments conducted on six Ultisols. An Inceptisol and a Histosol were also sampled and four lime treatments established, providing a range in pH and organic matter content. Three levels of Zn as ZnSO4 · 7H2O were added to each soil. Soybeans [Glycine max (L.) Merr., cv. Centennial] and corn (Zea mays L., cv. Pioneer 3369A) were grown successively in the greenhouse, each for 5 weeks. Mehlich 3 extractable Zn decreased with an increase in soil pH on only one of the eight soils, but Zn concentration in plants grown on all soils decreased with an increase in soil pH. Mehlich 3 extractable Zn alone accounted for little of the variation in the plant Zn concentration of the two crops. Including soil pH and CEC in the model increased the R2 to 0.56 and 0.50 for soybeans and corn, respectively. When the squared and first‐order interaction terms of these variables were considered, the R2 increased to 0.76 for soybeans and 0.66 for corn. For corn grown in the field, these same variables were found to be important in Zn soil test calibration. The form of the regression equation proved to be illogical, however, because the range in soil properties was not sufficient to produce a reliable prediction equation. Regression equations from the greenhouse were then adjusted to predict the leaf Zn concentrations of crops grown in the field. For corn, an equation that gave reasonable estimates of leaf Zn concentration in the field was developed. This equation may be used to interpret the need for Zn fertilization over a continuum of extractable Zn concentration, pH, and CEC in soils.

Residual soil P values for permanent pastures on reclaimed scrubland from Galicia (NW Spain).

In the reclamation of scrublands of Galicia in NW Spain, fertilization is necessary to establish pastures. The area is particularly responsive to P fertilizer. In order to maximize the efficiency of use of fertilizer in planning fertilization programs, it is necessary to take into consideration the residual as well as the freshly added P. Phosphate fertilization experiments were conducted in four sites in Galicia having a range in soil properties. The treatment design allowed estimation of residual P one year after fertilization in terms of freshly applied P equivalents. Four non-linear models were fitted to the data from the experiments after it was determined that residual soil P one year after fertilization was proportional to the amount of P applied. The estimated proportion of P remaining one year after application appeared to be independent of the model chosen. The Mitscherlich performed best from the standpoint of average residual mean squares, total rank, residual behavior after the fit and ease of fit. The percent of fresh fertilizer equivalent estimated one year after addition ranged from 60–90 for soils formed from granite, 30–60 for soils from slates, and 30 for soils over schist and gabbros.

The Distribution and Abundance of Vesicular Arbuscular Endophytes in Some Western Australian Soils

The distribution and abundance of large-spored vesicular arbuscular (VA) endophytes was examined at three localities in Western Australia. Within each locality, soil samples were collected from sites with a range of soil properties and superphosphate histories. Vesicular arbuscular endophytes were widespread. Spores were found in all but five of 104 samples. In two of the samples where spores were not found, plants grown in the soils formed VA mycorrhizas. Root infection by a fine endophyte resembling Rhizophagus tenuis was also frequently observed. Five spore types were found. Honey-coloured sessile spores were present in 85% of the samples. The yellow vacuolate spore type was the second most common endophyte, but its distribution was mostly limited to cultivated and fertilized soils. Endophytes other than the yellow vacuolate spore type occurred on both virgin and agricultural soils. The distribution of honey-coloured sessile and yellow vacuolate spores in cultivated soils appeared to be associated with variation in soil pH. The total numbers of spores collected on a 106 μm sieve were not correlated with soil pH, NaHCO3-extractable phosphorus or superphosphate history.

INFLUENCE OF SOIL-STRUCTURE INTERACTION ON THE EARTHQUAKE RESPONSE OF BUILDINGS

In this paper, the influence of the soil properties on the dynamic response of a building subjected to different earthquakes is quantitatively analyzed. The proposed mathematical model for foundation and surrounding soil consists of (1) an equivalent soil-foundation mass M0, (2) a translational spring of stiffness K0, (3) a rotational spring of stiffness Kθ, and (4) dashpots for damping in translational and rocking modes. By using existing theory, values for K0and Kθhave been selected for a rigid foundation supported by semi-infinite soil mass. A numerical incremental-iterative type of scheme is devised and a linear acceleration method is utilized to obtain the elastic and inelastic structural response. Digitized earthquake records from El Centro 1934 and 1940 have been utilized to study the influence of foundation conditions on the structural response of a multi-storey building. A range of soil properties and soil damping characteristics are chosen and various response curves are presented; this leaves complete freedom to a soil and foundation engineer to choose any desired value of the soil properties.Numerical analyses of a three-storey building show that for the foundation, the largest relative displacement occurs in the translational mode and the largest foundation rotation can be obtained by combining translational and rotational modes. It is shown that the natural frequency for a building in which the foundation effects are considered is always lower than that obtained for a building in which foundation effects are neglected. It is found that the soil damping characteristics have a major influence on the structural response, but Poisson's ratio of the soil has a minor influence. Various other recommendations regarding earthquake foundation designs are also suggested.