Physical, chemical and macro-micromorphological characteristics of some alluvial soils irrigated with different water resources

الملخص EN

In addition to the Nile River, which is the main resource of water, there are alternative sources, i.e.

groundwater, agricultural drainage water and sewage water are used for irrigation in many parts of Egypt.

The aim of this work was to study the morphological and micromorphological features as well as some physical and chemical properties of the alluvial soils irrigated with these waters at Assiut city.

Four sites were chosen to represent the soils irrigated with different water sources, i.

e.

the fresh Nile water, artesian water, Nile water polluted with incompletely treated sewage water and Nile water polluted with agricultural drainage water.

One profile was chosen and dug to represent the soils of each site.

The profiles were morphologically described and some physical and chemical characteristics of their layers were measured.

Thin sections were prepared from undisturbed surface and subsurface soil samples, then micromorphologically examined.

The obtained results revealed that the studied soils are generally flat to almost flat, deep, of water table deeper than 150 cm and are moderately well drained (the sites irrigated with artesian and agric.

drainage polluted Nile waters) to well drained (the sites irrigated with Nile and polluted sewage waters).

Although, the surface and subsurface layers of soils irrigated with Nile, artesian and sewage polluted Nile waters have the same texture grade (sandy loam), some properties such as, matrix colour, structure and consistency, differ in the surface layer irrigated with sewage polluted Nile water.

Soil irrigated with sewage polluted Nile water has the highest contents of organic matter, pH, available Zn, Cu and Pb, whereas, irrigated with artesian water has the highest amounts of calcium carbonate, EC, ESP, soluble Ca, Mg and K, and extractable Fe, B and Ni.

Moreover, the soil irrigated with agric.

drainage polluted Nile water contains higher values of soluble Na, CEC and available Mn than the others.

Micromorphological features of the studied soil samples indicate that they have apedal soil materials, with mainly primary structure.

Porphyroskelic and agglomeroplasmic fabrics characterize the soil surfaces representing soils irrigated with fresh Nile, artesian and sewage polluted Nile waters, while samples irrigated with agric.

Drainage polluted Nile water show silty-sized grains embedded in dense soil plasma.

The argillasepic plasmic fabric predominates over the other in the examined samples of the studied soils.

Plasma separations are noticed as vo-in-sepic in all studied samples.

The dominant void type is vugh, that is mainly interconnected, irregular, ortho and / or metavugh.

Vesicles are noticed in all-surface samples.

Channels and chambers are seen in the subsurface samples irrigated with fresh Nile and artesian waters as well as the subsurface ones irrigated with other water resources.

Planes are present as subparallel, skew and craze in the soils irrigated with sewage and agric.

drainage polluted Nile waters.

Thin stress opaque organo-argillans were presented on the walls of grains and voids, as well as argillaceous and carbonate nodules in the soils irrigated with fresh Nile and agric.

drainage polluted Nile waters.

However, void walls and embedded grains are coated with ferri-arrgillans, as well as sesquioxidic, manganiferrous and ferromanganic-carbonate nodules are noticed in the examined samples of the soils irrigated with artesian and sewage polluted Nile waters.