Solonetz

Abstract: Soil structure is an important physical property of soil and has a great impact on the environment and agriculture. Dry aggregate size distribution and related soil structure indices are essential parameters in understanding the structural state of the soil. This study was conducted to determine the effects of different soil types and land uses on structure parameters and to relate them to selected soil properties. The investigation was performed on five soil types (Arenosols, Fluvisols, Chernozems, Gleysols and Solonetz), each from three different locations and under three different land uses (cropland, meadow and forest), so that a total of 135 undisturbed soil samples were collected. Dry sieving analysis was performed to obtain eight aggregate size classes (ASCs) (>10, 10-5, 5-3, 3-2, 2-1, 1-0.5, 0.5-0.25 and 10, 5-3 and 3-2 mm ASCs. Chernozems and Gleysols have more favorable structure than Arenosols, Fluvisols and Solonetz. Long term cultivation leads to the deterioration of soil structure and the formation of clods. Forest soils have a significantly better structure than soils under meadows and croplands. The application of principal component analysis and regression models identifies water retention at -33 kPa, bulk density and pH value as for the most important factors in predicting dMWD and dGMD.

Abstract: Summary A field and laboratory examination has been made of the soils of the Pilliga district of New South Wales, with particular reference to those showing solonetzic morphology. The area consists largely of alluvium from the Jurassic sandstones of the Warrumbungle Range, and grading diagrams for the sandfraction suggest that distribution of the soils follows the changes in depositional pattern. It seems probable that a soil type can occur, morphologically and chemically similar to that which has been described as solodized-solonetz without ever having been through the stages of solontchak and solonetz. The conditions under which such a profile could develop are: (a) a semi-arid to sub-humid climate, where the mean soil temperature is too high to permit either accumulation of organic matter or the long persistence in the groundwater of organic compounds capable of chelation; (b) a parent material sufficiently coarse textured to allow movement of clay and of fine silt simply by the mechanical action of percolating water, but not so coarse that the clay is washed completely out of the column; (c) a parent material extremely low in calcium-bearing minerals. This condition would obviously be met when the parent material of the present soil was part of a fossil profile formed in a humid or strongly leaching environment; (d) the presence of vegetation capable of absorbing silica from the soil water and returning it to the surface in leaf fall in a sufficiently finely divided form; (e) a source of sodium ions. The solodized-solonetz could consequently be considered as the normal soil found on coarse-textured parent material in the semi-arid to sub-humid zone of the warm temperate and sub-tropical areas.

Abstract: Soil salinization arises due to the build up of soluble salts at or near the soil surface. Salts accumulate by primary and secondary processes that alter the soils physicochemical properties and lead to direct and indirect soil degradation. Results are presented here from the study of three contrasting salt-affected landscapes. The Chott el Fedjadj, Tunisia, is a naturally salt-affected basin containing saline sediments deposited during a marine incursion. The endoreic conditions lead to salt recirculation, concentration and reprecipitation. In the Guadalentin Valley, Spain, increased irrigated agriculture has led to aquifer overexploitation releasing gas and salts. Irrigating with the resultant contaminated groundwater has induced soil salinization. The salt accumulation and translocation is dictated predominantly by irrigation method, water quality and quantity. Hungary has the largest expanse of naturally salt-affected soil in Europe, with the dominant soil type being solonetz. In Hungary the type of salt-affected soil development is related to the salts present, hydraulic properties of the soil and depth and quality of the watertable. In Tunisia a catenary relationship of increased water and soil salinity towards the centre of the chott is found, whereas in Spain the highest salinities were found under flood irrigation with the valley displaying a complex spatial distribution of soil salinity. The sediment distribution in Hungary dictates that solonchak soils are found mostly in the Danube–Tisza interfluve and solonetz soils in the Tisza floodplain, with localized variations in soil type related to watertable characteristics. Copyright © 2001 John Wiley & Sons, Ltd.