ALTERATION OF SOME ALLUVIAL SOILS IRRIGATED WITH DIFFERENT WATER RESOURCES, ASSIUT, EGYPT. | ||||
| Assiut Journal of Agricultural Sciences | ||||
| Article 11, Volume 37, Issue 2, July 2006, Page 165-184 PDF (1.03 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ajas.2006.274190 | ||||
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| Authors | ||||
| M. A. Faragallah1; M. A. Essa2 | ||||
| 1Soil and Water Sci. Dep., Fac. Agric., Al Azhar Univ. Assiut, Egypt | ||||
| 2Dept. of Geology, Fac. of Sci., Assiut University, Egypt. | ||||
| Abstract | ||||
| The present work represents the study of the origin, uniformity, weathering as well as any mineralogical changes that occur in the fine and very fine sand fractions of some Nile alluvial soils irrigated with different water sources. Four localities were chosen to represent soils irrigated with Nile, artesian, incompletely sewage-polluted Nile and agricultural drainage-polluted Nile waters. Fine and very fine sand fractions were separated into heavy and light minerals. The levels of heavy minerals within studied sand fractions are relatively low (0.46 – 8.75 %) in all studied soil samples. Heavy minerals include opaque and non-opaque minerals. Opaque minerals are the less abundant in all examined soils samples, without any specific trend with depth. The non-opaque minerals are present in the following manner: pyroxenes (including augite, diopside, hypersthene and enstatite) are in pronounced amounts, followed by amphiboles (including hornblende, chloritized hornblende and tremolite) and epidotes in most sites. Sphene, biotite, zircon and garnet are recorded in relatively moderate amounts, whereas, rutile, Tourmaline and staurolite are found as traces. Only one apatite value (0.51%) is detected in the soil surface irrigated with artesian water. The light minerals are the most dominant in the examined fine and very fine sand fractions with contents up to 99.54%. Quartz is the most abundant mineral in all studied soil samples, whereas, feldspars are found in small amounts followed by calcite. These mineral assemblages indicate that soil materials have originated from igneous, metamorphic and sedimentary rocks. Regarding soil uniformity and weathering, these soils are stratified and are of multi-origin and/or formed under multi-depositional regimes, and are weakly affected by weathering. Respecting alteration of some minerals, slight alteration of hornblende to chlorite at the grain peripheries, and slight to moderate feldspar alteration to sericite have been noticed in various studied soils. Plagioclases represent the main altered feldspars in all studied soils followed by orthoclase and microcline. These alterations may be mainly due to processes of geochemical weathering in the source minerals of these soils. Concerning correlation coeffici-ents between DTPA-extractable metals, i.e. Fe, Mn, Zn, Cu, Pb, Ni as well as B and its bearing-minerals in soils, there are insignificant relations and almost negative in most cases, indicating that these minerals do not express the main sources of these elements in the studied soils. Instead, these considerable extractable | ||||
| Keywords | ||||
| Sand mineralogy; alteration; sewage; agricultural drainage; artesian water | ||||
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