A.A. Afify, H. M. A. El Tapey and E.E. Massoud( 2005). The Genesis And Spatial Distribution Of Soil Nutrients In The Physiographic Units Of North SinaiJ. of Appl. Sci., 20 (4): 748 – 767
Abstract: In order to get an overall view of the genesis and spatial distribution of the soil fertility variations in North Sinai, they were delineated to be associated with the different physiographic units. These units were delineated as characterized by the spectral signature of Landsat Thematic Mapper (TM7). They are: alluvial colluvial slopes, alluvial plain, wadis, fluvio-aeolian plains, aeolian plain and aeolian dunes. These units were categorized as having well drained soils. Another category of somewhat poorly drained soils includes pro-deltaic plain, inter-deltaic plain, lacustrine sediments and sabkhas. Other units in the study area are not promising ones for agriculture use, being with logged and submerged esturine sediments, esturine bay bar or as highlands of rock structures. Seventeen soil profiles, representing these physigraphic units were studied for the assessment of soil fertility relationship with physiographic and soil modes. Hence, the main soil characteristics and inherited macro nutrients {nitrogen (N), phsphorus (P), and potasium (K)} and micro nutrients {iron (Fe), manganese (Mn) and zinc (Zn)} were determined. It was found that soil N, P, Fe and Mn nutrient levels were much affected by the redox condition in the poorly drained soils, which include more nutrient level of those elements more than those in the well drained ones. Within the group of somewhat poorly drained soils the inter-deltaic plain includes the highest values, being with high clay and organic matter contents. In well drained soils available P levels were recorded with relatively higher values more in wadis than those in alluvial colluvial slopes and, fluvio-aeolian plain, aeolian plain and aeolian dunes. In wadis, the highest contents of P are related to the geomorphic processes. The vertical distributions of available P and K (strongly cycled) in the vegetated soils, their distributions becoming significantly concentrated in the surface whereas in bare soils (more weakly cycled) K distributions becoming deeper. The vertical distribution of Mn is somewhat following the same behaviour (Mn cycling), which increased toward the soil surface, but reduced with depth. It can be expected that vegetation change alters the vertical distribution and bioavailability of mineral elements. The soil nutrient test indicates that K levels are high in the alluvial plains, wadis, pro-and inter-deltaic plains and sabkhas. Fe is adequate in all physiographic units. Mn is adequate in wadis, pro-and inter-deltaic plains, lacudtrine sediments and sabkhas. Zn is only adequate in inter-deltaic plain. For each nutrient, the rest of physiographic units are suffering from that nutrient deficiency, which should be corrected and compensated by adding the nutrients as fertilizers.
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