توزيع و إعادة توزيع المحتوى المائي و الجهد المائي في المنطقة الجذرية للشعير

الملخص EN

A field study was conducted in 10 m × 20 m field plot to study distribution and redistribution of water content and water potential during time between irrigation of barley under shallow water table.

Profiles of initial water content ( measured gravimetrically) and water potential (measured by tensiometres) indicated high agreement.

While cute increase in water content and potential occurred above 40 cm only slight increase occurred below 40 cm.

Rate of change in water content ( t  ) during first irrigation was the highest in the surface 0-10 cm layer (0.005 cm3.d-1) and decreased drastically to reach 0.0004 cm3.d-1 at 40 cm and approached zero below 60 cm.

Values of total water potential increased above 40 cm after 2 days following irrigation and marked -110, -100, - 90 and -103 cm H2O for the 10, 20, 30 and 40 cm depths respectively.

A cute change in total water potential in the surface 0-10 cm layer occurred after 25 days following irrigation and decreased sharply with increasing depth and marked -850, -260, - 150, , -140 at 10, 20, 0 and 40 cm depths respectively.

No change in water potential was detected below 50 cm as well as water content profiles below 60 cm.

This study clearly indicates that the process of water distribution and redistribution requires the determination of changes in water content and water potential as a function of depth and time which in turn is essential to determine both deep percolation losses and capillary rise contribution to crop water requirements that are essential for irrigation water management.