Relationship of Land Use History and Chemical Properties of Soils with Their Allelotoxicity

Eurasian Soil Science - The influence of land use history and chemical properties of soils on their allelotoxicity has been studied. Twelve soil samples collected on the Russian Plain and seeds of...     

Relationship between water tension and electrical resistivity in soils

An increase in the soil water content results in a decrease in the electrical resistivity of soil. This relationship obeys an exponential equation. When the water content is below the range of capillary-film water, the clearest relationship between the electrical resistivity and water content is observed, which allows the soil and ground waters to be studied. At a high water content, the dependence of the electrical resistivity on the content of exchangeable anions, the pH, and some other properties is detectable.     

Age, size distribution and growth of native and cultured Japanese scallops in Possjet Bay, Sea of Japan, Russia

Stock size, distribution, size and age composition, and growth of Japanese scallops,Mizuhopecten yessoensis, were studied at eight sites in Possjet Bay, Sea of Japan, Russia. At seven sites, most of the scallops were cultured animals (seeded as one-year-olds in 1986–1989). At the eighth site, only native (i.e. naturally settled) scallops were present. Cultured scallops had an irregular strip-like distribution at all locations. Maximum growth of scallops occurred in the northwestern part of Reid Pallada Bight. Only at Temp Bight did both native and the majority of cultured scallops attain the harvest size of 100 mm shell height at age 3 years. At all other sites in Possjet Bay, cultured scallops reached harvest size at an age of 4 years.     

Anisotropy of the properties of some anthropogenically transformed soils of podzolic type

It is shown that the horizons and profiles of anthropogenically transformed soils of podzolic type—light typical agrozems, typical texture-differentiated soils developed from glaciolacustrine loamy sands and clays and from noncalcareous mantle loams, agrosoddy deeply podzolic soils developed from noncalcareous mantle loams, and agrosoddy shallow-podzolic soils developed from noncalcareous mantle loams and from calcareous loams underlain by ancient glaciolacustrine loams and clays—are characterized by some anisotropy of most of their properties. The highest anisotropy is typical of the field water content, bulk density, and total porosity. The coefficients of anisotropy (gradients) calculated for the separate horizons as the ratios between the values of the properties measured in the horizontal and vertical directions (k = P_horiz/P_vertic) of these properties are much higher than those of other soil properties. The coefficient of anisotropy of the soil profile (K) is suggested as the coefficient of correlation between the values of a given property determined in the horizontal and vertical soil sections. For the considered properties, K varies from 0.4 to 0.6. For other soils properties, such as the solid phase density, the electrical resistance determined in a laboratory and in the field, and the organic carbon content, the coefficients of anisotropy are close to 1.0. The clay content has an intermediate anisotropy. The values of anisotropy and its direction (gradient) should be taken into account upon the assessment of the soil physical properties and the processes controlling them; this is particularly important in the study of soil transformation. The revealed regularities of the soil anisotropy make it possible to suggest a new interpretation of the data on the distribution of water and energy in soil profiles.     

Thermophysical Properties of Histosols on Lowmoor Peat

Eurasian Soil Science - The temperature regime and the dependence of thermal diffusivity on the volumetric water content in high-ash drained peat soils (Sapric Drainic Histosols (Lignic)) on woody...     

Hydrophysical Properties of the High-Ash Lowmoor Peat Soils

The water retention curve (WRC), density, botanical composition, and ash contents were determined for high-ash lowmoor peat soils (Rheic Sapric Histosols) developing on the floodplain of the Yakhroma River (Moscow oblast) from the herb–hypnum and hypnum peat enriched in carbonates, agromineral peat soils (Rheic Drainic Sapric Histosols (Mineralic)), and peat soils developed from woody peat underlain by herb, sedge, and woody peat layers (Rheic Sapric Histosols (Lignic)). The WRC was determined by capillarimetric method in the range of water pressure from 0 to 80–90 кPa. For the studied peat soils, the WRC represents a close to linear dependence of the water content on the water pressure in semilogarithmic scale. In contrast to mineral soils, a characteristic point of the air-entry pressure is virtually absent on the WRC of peat soils. The WRC of peat largely depended on their density: denser peat samples were characterized by a higher water content at the same water pressure, which attests to the increased water retention capacity. An increase in the degree of decomposition of peat and its ash content also leads to the rise in the water retention capacity, but the effect of these factors is considerably smaller than the effect of peat density.     

Geostatistical Analyses of Soil Salinity in a Large Field

Estimating spatial variability of soil salinity is an important issue in precision agriculture. Geostatistical methods provide a means to study the heterogeneous nature of spatial distributions of soil salinity. In this study, geostatistical methods, kriging and cokriging, were applied to estimate sodium adsorption ratio (SAR) in a 3375 ha agricultural field. In cokriging, more easily measured data of electrical conductivity (EC) were incorporated to improve the estimation of SAR. The estimated spatial distributions of SAR using the geostatistical methods with various reduced data sets were compared with the extensive salinity measurements in the large field. The results suggest that sampling cost can be dramatically reduced and estimation can be significantly improved using cokriging. Compared with the kriging results using total SAR data, cokriging with reduced data sets of SAR improves the estimations greatly by reducing mean squared error and kriging variance up to 70% and increasing correlation of estimates and measurements about 60%. The sampling costs for SAR estimation can be reduced approximately by 80% using extensive EC data together with a small portion of SAR data in cokriging.