Moisture distribution in high ground water table sandy soils under mini- sprinkler irrigation system

الملخص EN

The research was run in a-73 cm ground water table sandy soil at Siwa Oasis, A.R.

E.

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Soil surface is undulated.

A nozzle operating pressure of 0.69 bar (10 psi), yielded the minisprinkler (Mikroregner ) a precipitation rate of 7.56- , 1.52- 0.80 -and 0.00 mm / h at zones surrounding the mini -sprinkler, 1 (0-120-), 2 (120-230-), 3 (230-300) and 4 (300-370 cm) After one hour and 45 minutes with the given precipitation rates resulted a change of soil moisture content of 3.31 , 0.67-, 0.04 and 0.00 vol.

% in the 0-40 cm soil layer for the above mentioned zones, respectively.

Ignoring the two abnormal measurement values of 29 - at the mini-sprinkler and 19 mm / h at 50 cm left-hand of the mini-sprinkler resulted in a change of soil moisture content of 2.54 vol.

% in the 0 - 40 cm soil layer in the 1 (0 -120 cm) zone.

Nevertheless, an application of 3.4 mm, on the average through 1 hour and 45 minutes across a 144 square meters area irrigated by four mini-sprinklers, 6 meters apart, caused an wetting increase of 2.34 -, 2.33-and 2.40 vol.

% at the 0 -40 cm soil layer related to the moisture content before irrigation of the three zones , 1 ( 0-120-), 2 ( 120-230-) and 3 + 4 ( 230-370 cm), respectively.

Such discrepancy might be attributed to variable depth of ground water in the three zones with different contribution through upward capillary flow from the ground water table.

A mini-sprinkler with better application uniformity at low nozzle operating pressure would be preferable.

It is advisable to use such mini-sprinkler irrigation only as supplemental irrigation for orchards in Siwa Oasis to control water logging problems, save good quality irrigation water and reduce irrigation costs.

The saved good quality water would be applied for wider land reclamation projects.