Soil Structure in Vertisols of the Blue Nile Clay Plains, Sudan

Abstract

WITH 2 PLATES SummaryA survey of 1-5 million hectares of the Blue Nile clay plains has shown the majority of soils to belong to the order of Vertisols. The morphological characteristics of these soils are described and compared with similar soils in other parts of the world. Soil cracking, structure, surface mulching, and micromorphology are discussed in detail.The use of crack width is considered to be unsatisfactory as one of the criteria for differentiating Vertisols and Entisols. Cracking may prove to be a useful criterion for land suitability classification. Three different types of surface mulch have been distinguished. A separation between soils possessing surface mulches and hard crusts is recommended at the family level.The unequal stresses and strains which result from the swelling and shrinking processes are responsible for the aggregation and structure formation within these soils. Platy layers were found to restrict water penetration and root development. The term 'bicuneate' is proposed for the description of the wedge-like structure of the soils.The micromorphology appeared to be strongly affected by pressure : numerous slickenside faces were recognized. J Y ebe Kardos. Sandstones of the Nubian series underlie the northern area and appear at the surface immediately S of Guneid. The area is flat and level, with the exception of abandoned river channels which are particular1 evident between the Blue Nile, Dinder, and Rahad sloping, 0-5-0-8 m per kilometre. Drainage is ve restricted, fue to the impermeability of the clay and the lack of relie? developed. Basement Complex, which underlies t K e clay, outcrops rivers. T o the H of the Rahad the land is more featureless, flat and ently

A GIS-Based Comparative Analysis of Frequency Ratio and Statistical Index Models for Flood Susceptibility Mapping in the Upper Krishna Basin, India

“…In the UKB, the maximum FR value (2.78) was identified for Pellic Vertisols (Vp) followed by Chromic Vertisols (Vc), which was 1.19 (refer to Table 2). Vertisols soils have a high moisture-holding capacity due to the maximum clay content, which varies between 40 and 80% [90,91]. Therefore, the areas of the UKB with Vertisols soils (Vc and Vp) are more vulnerable to flooding than other types of soils.…”

“…About 29 boats in Kolhapur, 43 in Sangli, and 17 boats in Satara were busy evacuating people. In the Kolhapur district, 89 roads were underwater [91]. According to the Vadnere committee report [52], about 1.66 lakh hectares of seasonal and perennial crops were affected in 28 tehsils of Satara, Sangli, and Kolhapur districts.…”

Effect of crop rotation and residue management on properties of cracking clay soils under irrigated cotton‐based farming systems of new south wales

“…The dominant clay mineral is montmorillonite, which is usually associated with illite and kaolinite. The soils have a clayey texture (with clay contents ranging from 30 to 80 per cent) and form cracks (unstable macropores) which close on wetting due to swelling of the soil (De Vos and Virgo, 1965;McGarity, et al, 1984;Dexter, 1991). In addition, stable macropores and aggregates attributable to the interacting activities of soil organic matter, exchangeable cations, plant root systems, soil macrofauna and microflora occur in these soils (Cook, et al, 1992;Dexter, 1991;Little, et al, 1992;Materechera, et al, 1991;.…”