Monitoring soil salinity to assess soil degradation map in some flood irrigated calcareous soils at Nahariya region, Egypt

الملخص EN

The studied area is known as Mina Valley, which covers an area of about 85000 feddans.

It was subjected to soil survey conducted by ULG Consultants Ltd., 1979.

In the current study, aerial photo interpretation and the grid technique (geo-statistics) were used for mapping the units and to identify the soil salinity in Mina Valley in the year of 1998, respectively.

A comparative study was made for monitoring the changes in soil salinity map illustrated by ULG (1979) as well as to assess the soil degradation in the studied area.

Data obtained from the crossing technique between the physiographical soil mapping units and both soil salinity maps of the years 1979 and 1998 illustrated that the soils could be grouped in three groups: a) The improved areas are of about 17700 feddans (21.0 % of the total studied areas).

b) The degraded areas are of about 34400 feddans (41.0 % of the total studied areas).

c) The not changed areas are of about 31700 feddans (37.8% of the total studied areas).

These results reflected that areas are suffering from soil salinity on the different mapping units could be distributed as follows: a) The foot slopes of the elongated hills, representing 9650 feddans (11.49 % of the total studied areas).

b) The toe slopes of the elongated hills, representing 8990 feddans (10.71 % of the total studied areas).

c) The back slopes of the elongated hills, representing 5240 feddans (6.2 % of the total studied areas).

d) The summit of the elongated hills, representing 3790 feddans (4.5 % of the total studied areas).

e) The inner part of Mina Valley depression, representing 3324 feddans (4.0 % of the total studied areas).

f) The outer part of Mina Valley depression, representing 1271 feddans (1.5 % of the total studied areas).

This area is the most degraded one.

Data obtained from the current mapping units representing the vertical and horizontal distribution of the accumulated salts in the soils of Mina Valley indicated that the degraded could be grouped as saline soils resulted from the climate of arid and semi-arid regions prevailing.

Sodium sulfate and chloride are the main predominant salts.

Based on the guidelines proposed by FAO (1985), some of the irrigation water have slight to moderate restrictions for use.

The obtained results revealed that the major part of the previous reclamation program in the studied area had no applied a leaching fraction as a part of the schedule irrigation water to leach out the soluble salts from the root zone during cultivation of moderate and .

strong saline soils.

Furthermore, the leaching requirements budget, which should be involved in the past reclamation program of this area, were not fulfilled.

Also, that conditions reflected the inadequate water budget needed to cover the crop requirements and the leaching fractions.

Thus, the very strong saline soil areas should be reclaimed by applied adequate leaching requirements