The size distributions of structural elements at the aggregate, microaggregate, and elementary-particle levels of soils are studied experimentally. The microaggregate and particle makeup was studied in 0.05 percent sodium pyrophosphate solution and with increasing lengths of ultrasonic treatment (80 kHz). Several subdistributions are identified: I, clay components, up to 5 mum II, sand components, 5-90 mum; III, > 90 mum, and so on. Subdistribution III and higher-order subdistributions exhibit the log-normal distribution; the elementary-particle, microaggregate and aggregate compositions differ in terms of the cumulative percentages of the subdistributions. The probabilistic characteristics of the distributions can be used as structure parameters in modeling processes that involve soil structure.
An investigation of the spectral reflectivity of soils of the Sierozem and of the effect of salinization on it indicates that the effect of soluble salts on the reflectivity of soils depends on the season of the year, the type of soil, and the degree of salinization. Equations relating rho750 to the concentrations of Na+, Ca2+, SO42-, and Cl- in the soils and to total readily soluble salts in virgin and cultivated soils are derived. The possibility of evaluating the degree of salinization of soils from the values of rho750 in the surface horizons is investigated.
Mixed pine forests on the western outskirts of Moscow that are subjected to industrial stress are used to show that the burrow network of moles and mouselike rodents is able to accumulate heavy metals and other pollutants in the zone of influence of heavy highway traffic. Significant alkalinization and increase of the content of adsorbed calcium were observed in the soil near the highway. Possible mechanisms of these processes are discussed.
The main factors causing unsatisfactory soil-melioration condition of irrigated lands in the arid zone are discussed. A call is made for a sharp change in both the theory and practice of melioration, fertility, and soil ecology. It is suggested that current problems of the use of natural resources be resolved on the basis of a new ecological and meliorative conception.
The task of creating a comprehensive model of soil formation for tropical and extratropical regions, based on soil properties, is of primary importance. The unique conditions of formation for tropical soils (including the variety of morphostructural and morphosculptural topographic forms, prolonged and varying histories of landscape development, variegated composition, polygenetic and polychronic character of the parent materials) lead to the formation of polyclimax soils. Ferrallitic soil properties are inherited from earlier geologic times; they are a paleogeographic characteristic of a given region and lithorelict soil features in the tropics. Use of the current three-component principle (profile, composition, regimes) of classification of tropical soils suggests joining them with soils of other soil-climatic zones with similar genetic profile features.
Under natural conditions, Chlorsulfuron and its degradation products are lost from the soil slowly. Two years after its application, 10-15 percent of Chlorsulfuron remains in the soil in unaltered conditions, but only 2 percent of this amount is in the plow horizon of Sod-Podzolic soils; the rest has been carried to greater depths. Some 25-30 percent (as carbon) of the Chlorsulfuron is present as degradation products.
Combinations of mesofaunal species (ecopleiads) that are functionally related to elementary soil processes (ESP) have been identified. The presence of some ecopleiad and its abundance in the soil corresponds to the site, time of occurrence, and intensity of strictly defined ESP. Such a zoological identification supplements soil identification by routine determination of seasonal and longer-term dynamics of ESP.
As a result of studies on the variability of soil microbial systems under anthropogenic influences, a new approach to the microbiological diagnosis of soils conditions is proposed, based on a combination of gradient analysis with an initiated microbial community method. It is shown that, independent of the nature of the pollutant, changes in the soil microbiota in response to increasing anthropogenic pressure are expressed in the successive replacement of four adaptive zones, which are shown to reflect separate levels of soil pollution. The diagnostic signs of the pollution levels described are explained, and a method for biodiagnosis of moderate levels is developed. The method suggested presents no strict requirements on control samples; it is relatively simple to use, and accessible for wide use; thus it has good prospects for acceptance in the field of local agroecological monitoring of soil pollution.
The soils and parent-material resources (joined in the concept of "soil substrates") of mountain geosystems are limited as a result of the lithologic and geomorphic processes from which they form. They are difficult to renew or nonrenewable if subjected to denudation. The paths of conversion from potentially unstable mountain geosystems and soil substrates to actually unstable and disintegrating states are discussed.
It is shown that narrow 2-3 row windbreaks, constructed to allow the passage of air, promote even distribution of the snow cover for a distance of 25 H (H = mean height of trees in the windbreak) and the accumulation of nutrients and humus, both vital to plants. This leads to a more even distribution of the root system within the soil profile and to the penetration of a significant portion of this system into deeper layers. Therefore plants on wooded fields utilize the moisture from deeper soil layers more fully and actively resist moisture deficits in drought years.
The lateral and seasonal variability in the composition of soil solutions in dry-farmed and irrigated micellar-calcareous Chernozems, separated by centrifugation from soil solutions at natural moisture content, are evaluated. About 75 percent of the cations in the soil solution are bound in associations; the chief complexing agent is organic anions in the soil solutions of the dry-farmed soils, and sulfate ion in the irrigated soils. The application of gypsum causes a sharp decline in the percentage of organic anions. When manure is applied, the concentration of organic anions is unaltered, although the concentration of organic carbon (by the Tyurin oxidation method) is tripled.
Investigations of deep sections identified the direction of change in the hydraulic characteristics of Chernozems of the South Russian Steppe under various types of utilization. The present-day status of the characteristics is evaluated. There is a need to increase the amount of herbage in crop rotations and to create forest belts over the entire southern Russian steppe in order to restore the fertility of the Chernozems.
Changes in the composition and properties of Cinnamon Forest soils after prolonged use under various agricultural crops are described.
A model of the dynamics of freezing and the evolution of the temperature profile in soil covered with mulch during the winter is developed. The modeling results are compared with measurements made in tracts with bare soil and with soil covered by straw mulch and a mat of dead natural vegetation.
Data based on long-term integrated studies of the effect of smoke-stack emissions and industrial effluent on the environment are presented. The investigations were performed in the Orenburg region of the southern Urals, a region rich in natural minerals and consequently with a heavy accumulation of industry, including ferrous and nonferrous metallurgy, chemical and petrochemical plants, power plants, machine works, and the like. The region has extremely unfavorable ecological conditions: excessive levels of various micro- and macroelements in the atmosphere, the hydrosphere, vegetation, the soil, and animal life.
The total amount and fractional composition of potassium compounds in Podzolic soils of various particle-size composition vary through the profile. Seasonal variations in mobile potassium in Podzolic soils with various degrees of hydromorphic influence are investigated.
Air temperature and the amount of precipitation over the growing period are the most important factors in the uptake of radiocesium by plants. The radiocesium content of plants is directly correlated with the air temperature over the growing period (May-August) and inversely correlated with total precipitation (May-August) and with the spring and autumn reserves of water in the upper meter of the soil.
The characteristics of soil formation on calcareous moraines under broadleaf forest are discussed. Rock and hydrologic conditions play the key role in the interaction between the mineral and organic components of soils. Soil formation gives rise to practically coeval Brown Earth and Brown Earth-Pseudopodzolic soils in combination with Gley and Pseudogley soils.
A method is proposed for determining the volume of lateral flow in frozen soils based on the collection of water flowing through a frozen impervious layer. A set of the simplest equipment for such studies is described, and possible prospects of development of such studies are considered.
