SUMMARY AND CONCLUSION
A newly reclaimed area in the sandy western desert border of the Nile Valley of about 150 feddans was taken to evaluate the effect of soil managements such as methods of irrigation (drip and sprinkler) and adding some of amendments. According to a study was carried out in 1999 to evaluate the soil salinity, it was found that the area was saline gravely calcareous soil.
In 2000, three groundwater wells were dug but their water salinity was 1.8 dS/m. In 2002, The irrigation water sources were changed to agricultural drainage water of 0.9 dS/m and Nile water of 0.3 dS/m. The area was supplied with fixed sprinkler irrigation system at (10x9 m) for growing field crops and drip irrigation (spaced at 1 or 0.5 m) for growing vegetables and crops. Ninety two feddans were supplied with drip irrigation for growing fruit trees in holes filled with dredged clay materials and irrigated with drip irrigation system. A layer of (20-30cm) dredged clay materials to the surface as amendment to improve the physical and chemical properties of the drip or sprinkler irrigated crops area.
The objectives of this study are:
1- evaluating the effect of irrigation methods and soil amendments application on soil physical and chemical properties.
2- evaluating fertility status of soil after 10 years of cultivation as compared with control samples (uncultivated soil).
3- evaluating the possibility of growing trees in unproductive saline gravelly sandy soil using holes filled with other soil materials.
2- Soil sampling:
The area of the farm was sampled in 1999 to draw the salinity maps before initiating the farm, which showed that the soil of the farm at that time considered high saline soil. In 2009 forty seven profiles were sampled to represent the irrigation systems and the growing crops in the farm, each profile was sampled at four depths. Five profiles were dug from the uncultivated area around the farm as control profiles.
The results showed that:
1- In the sprinkler irrigated crops area:
- The average of fine particles percentage significantly increased from 7.88% in the control soil to range of 19.29 - 28.49% in the cultivated area for the surface layer. Also, the average of saturation percent (SP) values significantly increased from 19.2% in the control soil to range of 27.55 – 29.89 %.
- The average of ECe values significantly decreased from 5.51, 5.03 dS/m in the control soil to range of 1.45 - 1.55, 1.18 – 1.34 dS/m in the cultivated soil for the surface and the next subsurface layers, respectively.
- The average of O.M percentage significantly increased in the cultivated area comparing with the uncultivated one.
- The average of total CaCO3 percentage significantly reduced in the sprinkler irrigated area comparing with the uncultivated soil.
- The average of SAR values stayed in the safe level in whole area.
- The average of total N values significantly increased from 271, 165 ppm in the control soil to range of 573-709 ppm, 290 - 313 ppm in the cultivated soil for the surface and the next subsurface layers, respectively.
- The average of available P values significantly increased from 1.83, 1.42 ppm in the control soil to range of 5.75 - 6.11, 2.82 - 3.01 ppm for the surface and the subsurface layers, respectively.
- The average of the exchangeable K increased from 91.89, 88.43 ppm in the control soil to range of 122 - 187.2, 95 - 119.3 ppm in the cultivated soil for the surface and the next subsurface layers, respectively.
- DTPA- extractable Fe, Mn, Zn and Cu were significantly increased in the cultivated area for the surface and the next subsurface layers.
2- In the drip irrigated crops area:
- The average of fine particles percentage significantly increased from 8.83% in the control soil to range of 20.34 - 23.5 % in the cultivated areas for the surface. Also, the average SP values significantly increased from 19.6% in the control soil to range of 28.62 - 29.35% in the amended area for the surface layer.
- The average of ECe values significantly decreased from 5.45, 4.52 dS/m in the control soil to range of 0.96 - 1.34 dS/m, 0.75 – 1.08 dS/m in the cultivated soil for the surface and the next subsurface layers, respectively.
- The average of O.M percent significantly increased in the cultivated soil comparing with the uncultivated one.
- The average of total CaCO3 significantly reduced in the cultivated soil comparing with the uncultivated one.
- The average of SAR values in the surface layer was in the safe level of 4 for whole area.
- The average of total N values significantly increased from 150, 119.33 ppm in the control soil to range of 488- 503 ppm, 210.5- 284.17 ppm in the cultivated soil for the surface and the next subsurface layers, respectively.
- The average of the available P values significantly increased from 1.58, 1.24 ppm in the control soil to range of 5.24- 8.10 ppm, 2.31- 3.4 ppm in the cultivated area for the surface and the next subsurface layers, respectively.
- The average of the exchangeable K values significantly increased from 100.8, 99.2 ppm in the control soil to range of 235 - 261.75 ppm, 130.21- 138.84 ppm in the cultivated area for the surface and the next subsurface layers, respectively.
- DTPA- extractable Fe, Mn, Zn and Cu values significantly increased in the cultivated area for the surface and the next subsurface layers.
3- In the drip irrigated fruit trees area:
- The average of fine particles content and the saturation percent significantly increased under the tree and decreased away from the tree’s trunk.
- The average of ECe values significantly decreased under the tree’s trunk and increased away from the trunk.
- The overall average of organic matter increased under the trunk for the surface and the next subsurface layers.
- The average of SAR ranged from 18.6 - 22.56 at 2.5m away from the tree’s trunk and from 3.15 - 4 under the tree trunk for the surface and the next subsurface layers, respectively.
- The average of total N significantly increased from 346.8, 210 ppm at 2.5 m away from the tree trunk to 734, 387.2 ppm under the trunk for the surface and the next subsurface layers, respectively.
- The average of available P values significantly increased from 2.54, 1.86 ppm at 2.5 m away from the tree trunk to 7.46, 4.72 ppm under the trunk for the surface and the next subsurface layers, respectively.
- The average of exchangeable K significantly increased from 125.11, 109 ppm at 2.5m away from the tree trunk to 375, 200 ppm under the trunk for the surface and the next subsurface layers, respectively.
- DTPA- extractable Fe, Mn, Zn and Cu significantly increased under the trunk for the surface and the next subsurface layers, respectively.
Conclusion
1- The sprinkler irrigation leached the salts successfully from the saline sandy soils.
2- Drip irrigation leached the salts away from the tree’s trunk which encouraged the growth.
3- Application of the dredged clay materials improved the physical properties such as water holding capacity of the sandy soils and improved the soil fertility.
4- Cultivation of trees in holes filled with dredged clay materials mixed with organic matter overcomes the problems of salinity and gravely texture of the desert soil.