Francis D. Hole

Effects of animals on soil

Abstract Soil is defined here in terms of arbitrary boundaries rather than of functions of a soil body. Soil animals are defined in relation to their effects on the soil body. Animals living in the soil body and intimately related to it are indeed part of the soil. Animals living above the soil make contributions to it. Many animals are amphihabitant, that is, they live for a time in the soil and then in environments outside the soil. Exopedonic (outside the soil) and endopedonic (inside the soil) animals are considered with respect to twelve activities: mounding, mixing, forming voids, back-filling voids, forming and destroying peds, regulating soil erosion, regulating movement of water and air in soil, regulating plant litter, regulating nutrient cycling, regulating biota, and producing special constituents. Animals participate in numerous processes of soil formation and effect the usefulness of soils.

An approach to landscape analysis with emphasis on soils

Abstract Principal components of landscape are defined. The soils portion is termed the landscape pedoplasma, distinct geographic subdivisions of which are called soilscapes. Some concepts of morphology and fabric of soil pedons are adapted for application to entire landscapes. Terminology and numerical indices are suggested for characterizing polypedons and multi-polypedonic units, including soilscapes, as to size, shape and arrangement of the geographic units, population density of polypedons per unit area, and pedologic diversity in terms of local relief, slope, and soil drainage conditions, and in taxonomic terms. Some results of application of specific methods of soilscape analysis to published soil and topographic maps are reported. Geographic trends in soilscape variability are found on a broad regional scale as well as in local landscapes. This approach to landscape analysis is deemed useful in systematizing the great volume of cartographic data of modern published soil surveys and may help in the location of sites for detailed pedogeomorphic and land use field studies.

Estimation of comparative water transmission in two pairs of adjacent virgin and cultivated pedons in wisconsin

Abstract Hydraulic properties and soil morphology of principal soil horizons of paired virgin and cultivated pedons, each pair with identical soil classifications, were studied at two sites. The capacity of the two cultivated soils to transmit water under saturated conditions was reduced as compared with the virgin soil, whereas this capacity generally increased in unsaturated soil at corresponding moisture tensions. Compacted layers below the Ap had a drying effect on the overlying Ap at a wide range of flow rates, whereas a wetting effect resulted in Al horizons of the virgin pedons at similar flow rates, representing unsaturated flow. Extrapolation for interpretive purposes of hydraulic conductivity data measured in a representative pedon of a mapping unit to pedons in identical mapping units elsewhere has to proceed with care, as differences may be substantial. A rather wide range of physical properties is acceptable in a pedogenic soil unit when broad qualitative soil map interpretations are made. However, specific interpretations require more detailed data, as is illustrated with examples relating to soil suitability for on-site liquid waste disposal.

FIELD WATER BALANCE AND SIMULATED WATER RELATIONS OF PRAIRIE AND OAK-HICKORY VEGETATION ON DECIDUOUS FOREST SOILS

A steady-state model of atmosphere-soil-plant water relations, implementing both the combined energy balance, aerodynamic calculation of evapotranspiration and a five-layer Darcy soil-water flow system, was used to simulate on a daily basis the water status and budget of experimental plots with either prairie grass or oak forest vegetation. A field water balance study provided independent estimates of evapotranspiration and drainage, based on measurements of soil water at several depths during the growing season. Oak forest and prairie grass vegetation in southern Wisconsin showed an average evapotranspiration rate of 2.0 cm3cm-2 week-1 from mid-June to early October based on a water balance of the top 180 cm of soil. Simulation results were in close agreement with the field estimates, although differences in time distribution were shown, particularly for the prairie grass plots. Actual evapotranspiration would be greater than these results due to soil water uptake at depths below 180 cm. Soil water drainage was negligible during most of the growing season for vegetated plots whereas drainage from treatments without vegetation was slightly less than the precipitation received. Soil water content was generally lower on vegetated plots than on nonvegetated plots during the growing season. The model provided a means of evaluating some phenomena not measured in the field experiments. Simulations suggested that the oak vegetation was under water stress on more days during the growing season than the prairie grass.

SOME CHEMICAL AND PHYSICAL PROPERTIES OF CERTAIN SOILS OF AFGHANISTAN

Chemical, physical and micromorphological data are given for eight representative pedons from agricultural areas in Afghanistan. An explanation for the genesis of discoidal features is presented. Four soils are classified as Orthids, one as an Agrid, one as an Aquoll, and two as Fluvents.

Telling the Walking Public about Soils

Most soil scientists have a problem keeping Rapidograph pens from leaking. Unless the point itself is defective, the ink drains through the threads of the pen point. Most of the time the leaking is done on a good shirt! There is an inexpensive way of solving this problem. Try Teflon tape, available at any hardware store. Teflon tape is used by plumbers to seal threaded pipe. The half-inch width does the job-tape one layer over the threads and screw the pen point into the base. The pen will not leak.