الفهرس 
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Abstract
Evaluation of trials were carried out in three different areas at Minufiya Governorate for the influence of tile drainage on the fertility of the soils from the stand soil properties on nutrients status point of view.
- Both soil and water samples were analyzed for some determinations and the obtained results could be summarized as follows:
a) Soil chemical properties.
1- Soil salinity.
- In the three studied areas, soil EC (dS m-1), TSS (%) and the content of both soluble cations (Na+, K+, Ca2+ and Mg2+) and anions (Cl-, CO32-, HCO3- and SO42-) as meq / 1 were declined along the distance of beginning lateral, from beginning to the end, but its increased with the increase of soil depth. At the same distance along lateral and soil depth the soil EC, TSS and the content of soluble cations and anions in the different soil layers above the laterals were lower than those found among the laterals.
- In all tested soil samples, the predominate soluble cation was Na+ followed by Ca++, where the lowest one was K+, while, the predominate soluble anion was Cl- followed by SO42- in most soil samples and with the HCO3- in others.
- The values of relative change ”RC” of drained soil drowned, EC, TSS and the content of soluble cations and anions in the three studied areas, were negative compared with undrained soil and this negativity promoted along the laterals distance especially above the laterals.
2- Soil pH.
- Soil pH in the three studied areas and with all drainage treatments, was increased with the increase of soil depth.
- Soil pH above the lateral was lower than that between the lateral at the same depth of each distance of the lateral. In addition, soil pH was decreased with increase the distance from the lateral.
- The values of relative change (RC) of soil pH in relation with drainage periods were negative and become more negative above the laterals especially at the end of them.
3- Soil organic matter.
- Soil content of OM (g kg-1) in the three studied areas, was minimized with the increase of both soil depth and the distance of lateral length. At the same distance and soil depth, the soil content of OM above the laterals was lower than those found at a midway of them.
- The soils in the three studied areas characterized by low content (< 7.5 g kg-1) of OM. Relative changes ”RC” of soil content of OM have a negative values with drainage treatments and these negativity augmented above the laterals especially at the end of them.
4- Calcium carbonate (CaCO3).
- The content of more than 90 % of the studied soil samples was less than 40 g kg-1. The highest content of CaCO3 was found in the soil samples of El- Khadrawyia 3 and the lowest content was found in the soil samples of El-Khadrawyia 1.
- There are no clear effect of the drainage system period application on both soil content of CaCO3, and its vertical distribution in soil profile. In most soil profiles under study, the soil content of CaCO3 was decreased with the increase of soil depth.
- Slight decrease of soil content of CaCO3 was found above the laterals and at the end of them compared to that found at a midway of the laterals and at its beginning. These findings may be supported from the calculated RC values of soil content of CaCO3.
5- Cation exchange capacity (CEC).
- CEC values in the soil samples of the three studied areas were ranged from 43 cmol kg-1 to 30 cmol kg-1. These values were decreased with the increase of soil depth and the distance among the lateral length. Also, the soils above the laterals have a lower CEC compared with that in the soil at the middle of the laterals.
- In addition, most RC values of soil CEC were positive for the drained soils compared with that one unaffected by drainage.
6- Exchangeable sodium percentage (ESP).
- Soil ESP was increased with the increase of soil depth. At the same soil depth in the three studied areas, ESP above the laterals was lower than that in the middle of them. Also, soil ESP was declined with the increase the distance of lateral length. All RC values of ESP in the drained soils were negative.
b) Soil physical properties.
1- Bulk density (BD).
- Soil BD in the three studied areas was positively affected by the different tile drainage variables where it was increased with the increase of soil depth. Also, the soil BD above the laterals was lower than that at a midway of them. On the other hand, the soil BD was reduced with extending the distance of the laterals length. So, RC (%) values of BD were negative with the increase the distance of the lateral length and its were more negative in the soils above the laterals. Under the same treatment of tile drainage, the negative value of RC was varied from area to another.
2- Total porosity (TP).
- Total porosity values showed an opposite trend to that encountered with bulk density. In the three studied areas, TP was decreased with the increase of soil depth, where it promoted with long the distance on the laterals above and between them. Thus all RC values of TP were positive and increased positively at the laterals ends especially above them.
3- Hydraulic conductivity (K).
- Soil K in the three studied areas in relation with tile drainage variables takes the parallel found with TP and reversible trend with BD. So, all RC values for soil K were positive and become more positive at laterals end and above them.
C) Soil content of available macronutrients.
1- Available nitrogen (N).
- The soils content of both NH4-N and NO3-N (mg kg-1) in the three studied areas was varied widely from area to another. The highest content of NH4-N was observed in the surface layers, where the highest content of NO3-N was noticed at the soil depth of 15-30 or 30-60 cm.
- The soil content of available N in the soil above the laterals was lower than that found at a midway of them. Also, above and at the middle of the laterals, the soil content of available N was decreased along the distance of laterals length. In the three studied areas and at the same depth, these observations were detected.
- Values of RC of the soil content of both NH4-N and NO3-N in the three studied areas were negative, however it varied from area to another.
2- Available phosphorus (P).
- The highest content of available P (mg Kg-1) was detected in El-Khadrawyia 3 and the lowest one was found in El-Khadrawyia 2.
- The available P determined above and at midway of the laterals appeared that the highest content was encountered at soil depth of 0-15 cm and the lowest one was found at the soil depth at more than 60cm. Also, the soil content of available P above the laterals was lower than that found between them. On the other hand, the soil content of available P was decreased with extending the distance on the laterals length.
- All RC values of soil content of available P in the three studied areas were negative and become more negative above the laterals especially at the end of the lateral length.
3- Available potassium (K).
- The soil content of available K (mg Kg-1) was reduced with the increase of soil depth. The highest content of available K was found in the soil of El-Khadrawyia 3 and the lowest one was determined in the soil of El-Khadrawyia 2.
- Available K in the three studied areas showed a higher content in the soil between the laterals than that found above them. On the other side a reduction of this content was observed along the distance of lateral length. In addition all RC values of the soil content of available K were negative in the three studied areas and with all variables of tile drainage.
d) The soil content of available micronutrients.
- The soil content of the determined micronutrients (mg kg-1) (Fe, Mn, Zn and Cu) was diminished with the increase of soil depth. That occurred in the three studied areas, either above or at the middle of the laterals, but also along the distance of the lateral length.
- The content of available micronutrients varied among the soil areas, likewise among the micronutrients determined wherever, the arrangement of these micronutrients according to their content was Fe > Cu > Mn > Zn in the soils of El-Khadrawyia 1 and 3 and was Fe > Mn > Cu > Zn in the soil of El-Khadrawyia 2.
-The soil content of the determined available micronutrients in the soil between the laterals exceeded that one in the above them. This content also was decreased with prolonging the distance of the laterals length.
- All values of RC of the determined available micronutrients were negative in the three studied areas above and at a midway the laterals and at different distances of the laterals length,. The higher negative RC values were observed above and at the end of the laterals. Notwithstanding, the calculated values of RC were varied widely from area to another and also from micronutrient to another.
e) Chemical composition of drainage water.
- pH of the drainage water slightly changed in the three studied areas, wherever it ranged from 7.4 to 7.6.
- The highest EC (dSm-1) values (2.67) was found in the drainage water of El-Khadrawyia 2 followed by that in El-Khadrawyia 1 (1.78 dSm-1).
- There are a wide variations in the drainage water content (meq/l) of soluble cations and anions ,where the highest content was recorded in the drainage water of El-Khadrawyia 2 and the lowest one was found with the drainage water of El-Khadrawyia 3.
- the predominant soluble cations in the three drainage water, was Na+ and the lowest one was K+ , where the predominant soluble anions was Cl-1 followed by HCO3-.
- According to SAR values, drainage water in both El-Khadrawyia 1 and 3 were classified as moderate sodicity, where the drainage water in El-Khadrawyia 2 classified as high sodicity.
f) Drainage water content of macro- and micronutrients.
-The highest content (mg l-1) of both NH4-N and NO3-N was found in drainage water of El-Khadrawyia 2 and the lowest one was determined in the drainage water of El-Khadrawyia 1. In the three studied areas, the drainage water content of NO3-N was higher than that of NH4-N.
The highest content (mg l-1) of P was notid in the drainage water of El-Khadrawyia 2 followed by that detected in the drainage water of El-Khadrawyia 3. The drainage water in the three areas characterized by relative high P content.
-In the three studied areas, Mn represents the main micronutrient presented in the drainage water followed by Zn and Cu, while Fe content was nil. The highest content of the determined micronutrients was observed in the drainage water of El-Khadrawyia 1 and the lowest content was found in the drainage water of El-Khadrawyia 2.