PEDOGENETIC ASPECTS AS RELATED TO SOIL FERTILITY STATUS AT EL FAYOUM, EGYPT

Abstract

This study aims to identify the relation between some plant nutrients status and soil mineralogical constituents, that influences in soil fertility aspects. To achieve this objective, five soil profiles were chosen to represent the main soil sediments in El Fayoum region, which are varying in their origins, i. e., aeolian, recent lacustrine, fluvio-lacustrine, old lacustrine and Nile alluvial sediments. Consequently, there were wide variations in their different soil characteristics The obtained data of microscopic examination for light and heavy minerals (sand fraction), in addition to the x-ray diffractions of both silt and clay fractions were discussed to identify the different nutrient-bearing mineral assemblages and their contribution. Also, the various soil constituent-bound nutrients such as organic matter, carbonate, manganese oxide, soil mechanical fractions, amorphous and crystalline iron oxides were i crucial factors, due to their active charged surface which play an important role in the soil fertility status. Most of P and K amounts in soil were bounded with clay, silt and organic matter fractions in the old lacustrine and Nile alluvial sediments. Ca and Mg were more combined with carbonate fraction, especially in the old lacustrine sediment. A relatively high amount of S was bounded with organic matter, clay and silt fractions, however, bound S-fraction was 2 times of the bound of S-clay one, especially in the Nile alluvial and recent lacustrine sediments. Fe was more combined with crystalline and amorphous fractions of the Nile alluvial sediment. Mn was more related to MnO,, clay and iron oxide fractions in the Nile alluvial sediment. Zn and Cu were mostly combined with clay, amorphous and crystalline iron oxide fractions, especially in the Nile alluvial and fluvio-lacustrine sediments. Total P was relatively high in the soil surface layers, indicating that it is originated from soil organic component. The lowest and highest values of total and available amounts were found in the aeolian or old lacustrine and Nile alluvial sediments, respectively. The lowest and highest values of total and available Kand S were existed in the aeolian and recent lacustrine sediments, respectively. The lowest and highest values of total and available Ca and Mg-amounts were in the fluvio-lacustrine and old lacustrine sediments for total amounts and in the Nile alluvial and aeolian sediments for available ones, respectively. The lowest and highest amounts of total and available Fe were existed in the fluvio or old-lacustrine and Nile alluvial sediments, respectively. The corresponding values of Mn, Zn and Cu were in the aeolian or fluvio-lacustrine and Nile alluvial sediments, respectively.