الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
Abstract
5. SUMMARY
In recent years, increasing attention is being paid on soil test base fertilization for sustaining the productivity of gricultural soils leading to better efficiency and economics of nutrient use with off farm advantage of environmental security. The available nutrients administrate the fertility of soils and control the crops productivity. The possibility of using Geographic Information System (GIS) design soil fertility maps, involves lesser numbers of soil analysis and thus reduces the cost of operation, this is being emphasized by many workers. The aim of the current work is to evaluate the fertility status and employ GIS to produce fertility status maps in two studied locations, Shalakan farm station and El-Bostan farm station. Shalakan farm is located at south Delta in Kanater El-Khirya region Qualubia Governorate, representing an old alluvial soil; this area is covering 198 Fadden (82 hectare). On the other hand, El-Bostan Farm station is located at Nubaria region, north of Cairo-Alexandria Desert road, El-Behera Governorate; it covers 55 Fadden (23 ha) represents the new reclaimed sandy soil; this farm. Twinty soil samples, 10 surface and 10 subsurface, were collected from each study farm. To produce soil fertility maps via GIS, another ten surface soil samples were collected from each farm. The sample points were recorded with a global positioning system and mapped. Both soil physical and chemical properties were evaluated. The chemically available macronutrient N, P and K as well as the available micronutrient Fe, Mn, Zn and Cu were also evaluated in both study locations. Finally, the spatial analysis tools in GIS were used to interpolate the available nutrients in each farm to produce a map for each studied macro and micronutrients. The results could be summarized as follows:
Regarding Shalkan soils; the texture of soil effected soil deepth, was clay with high organic matter content (OM) content and cation exchange capacity (CEC) as well as available phosphorus and potassium. The pH values ranged from 7.15 to 7.98. On the other hand, the available nitrogen was low. Concerning the available micronutrients, the soil has high Fe and Mn but moderate in Zn and low to moderate in Cu.
The spatial distribution maps for the status of macro and micro-nutrients in Shalakan show that the nitrogen status is clearly deficient across the whole farm, 71.7 % of the farm area has less than 150 ppm available NH4-Nitrogen. On the other hand, the P, K, Fe, Zn, Mn, and Cu show a clear sufficiency across the whole farm area. In general, these soils can be classified as having moderate to high fertility status.
Regarding El-Bostan soils, the texture of soil was sand to loamy sand, where sand fraction ranged between 83.60 to 91.60 %. Most of the soils are low in cation exchang capacity (CEC), low in organic matter content (0.47 – 1.51) along with available phosphorus and potassium. The pH values ranged from 7.36 to 7.81.
The spatial distribution maps for the status of macro and micro-nutrients in El-Bostan show that most of the farm area, 94.8%, has less than 7.0 ppm available NO3-nitrogen which could be explained by the low amount of organic matter in the soils. The spatial distribution of available phosphorus show that the total farm area falls in the medium class, where the values ranged between 6.9 to 8.7 ppm. However, the distribution of available K status showed a clear low values distributed along the whole farm where 93.5 % of the total area has below 170 ppm available K. Data El-Bostan area has high amounts of chemically available iron and manganese; but has low amounts of zinc and copper.
Finally, findings of this study indicate limitations of the existing map of soil resources of both Shalkan and El-Bostan farms. The produced maps in the current study is considered the first attempt to produce maps of the fertility status for both studied farms. The interpolated maps for the status of macro and micro nutrients show a clear deficiency of certain nutrients in Shalakan farm such as nitrogen. It also shows a lack or moderate amounts of a number of available nutrients in El-Bostan farm, such as N, P, K, and Mn which is mostly related to the lomy sand texture as well as the low organic matter content compared with the soils of Shalakan farm which have high clay content and higher amount of organic matter and CEC value.