الفهرس Only 14 pages are availabe for public view
 |  | from | 84 |  |  |
| | | from | 84 | | |
Abstract
SUMMARY
The most common method of extraction, used universally in the analysis of soil salinity, is the saturation paste extraction. This procedure offers advantages of convenience, and greater extract volume, relative to direct solution extraction. As well, it can be reproducibly related to field water contents, and compensates for variation in soil moisture retention. Some investigators employ constant extraction ratios, which are more convenient to use and yield higher extract volumes without vacuum, but are not as closely relate to field soil moisture contents. Although the saturation extract remains the best for measuring total salinity, fixed extraction ratios have been found to be closely correlated with the saturation extract, in wide range of soils. Extraction using a fixed ratio may be particularly useful for monitoring relative changes in solute concentrations.
The objectives of this study were to explore:
(1) The relationship between the EC in soil saturation extracts and that in fixed-ratio extracts for Northwest plain soils of Egypt.
(2) The relation between soluble ionic concentrations in soil saturation extracts, and that in fixed-ratio extract.
(3) The relationship between SAR of saturation extract and SAR for various dilution ratios.
(4) The optimum extraction method for the electrical conductivity and the soluble ionic determination.
Soil samples form 36 sites located in Northwestern coast soils of Egypt were used, to achieve the objectives of the present study. Soil sampling sites from one to 15 were collected along the transects start at Km 50, Alexandria-Mattruh desert road until El-Salum. Soil sampling sites from 16 to 28 were collected form Bangr – Elsukar region, and soil sampling sites from 29 to 36 collected from Km 80, to Km 115 El-Nubaria region.
The soil samples were air-dried, ground, sieved to pass through a 2-mm sieve, and subjected to different chemical analyses according to U.S.D.A, (1954). Results showed that there was considerable variation in the properties of the tested soils for the selected areas. The samples showed different texture classes. The salinity varies from 0.28 to 8.32 dS/m; the pH ranges from 7.26 to 7.87, organic matter content from 0.24 to 4.74% and the calcium carbonate content from 0.47% to 70.5% Regarding the soluble cations and anions (meq/L), Ca+2 ranged from 1.5 to 78.45, Mg+2 from 0.90 to 69.35, Na+ from 2.43 to 198.6, K+ from 0.45 to 4.70, CO3-2 HCO3- from 1.66 to 11.91, Cl- from 1.55 to 323.31 and SO4= from 0.50 to 31.65.
In general, the soils in these areas were alkaline, and they have high CaCO3 contents as expected, since they are typic calciorthids soils, except the soils of El-Nubaria region that they are sandy soils. The soluble ions content widely varied among soils, depending upon texture of the soil and the organic matter content. For all soils, however, the soluble content and nutrients decreased, as the soil becomes coarse in texture. Thus wide range in salinity levels or soluble ions were obtained, for making comparisons between the