Pulse drip irrigation is a recent concept where small frequent irrigation applications are applied to saturate the soil and meet the plant water requirements. The field experiment was carried out during two summer growing seasons 2006 and 2007, it executed in Abo-Ghaleb farm, Cairo- Alex. Rood, 60 Km away from Cairo and the soil was sandy.Seed tubers were planted on 2 th of February and harvested on 28 th of May in two seasons,and the well water was used as irrigation source having EC 1.9 ds/m, the soil sample were taken up to 45 cm depth. Diameter of the lateral line was 16 mm (OD)with discharge of 2.1 l/h. The distance between emitters was 30 cm and between laterals was 70 cm. The present investigation aimed to study the effect of pulse drip irrigation under organic agriculture for saving water and increasing yield of potato. The following parameters were studied to evaluate the performance of pulse drip irrigation :( 1) Soil moisture distribution, (2) Application efficiency "AE", (3) Yield of potato "YP", (4) Water use efficiency of potato "WUE potato". The results indicated that wetted soil volume (more than or equal 100% of field capacity) in root zone"WSV≥100% FC", application efficiency, yield and water use efficiency of potatowere increased by increasing number of irrigation pulses where: (1) WSV≥100% FC in root zone increased from 9617 cm3 under continuous drip irrigation "CDI" to maximum value where it become 14272 cm3 after applying pulse technique on 4pulses at 100 % from actual irrigation requirements "IRa" under surface drip irrigation, recording an increase of 48%. (2)Maximum values of AE were 93.5%, 97% and 99.2% under 100 %, 75 % and 50% from IRa respectively with 4 pulses under surface drip irrigation.
(3)YP increased from 4.70 (ton/fed.) under CDI to maximum value, where it become 6.57 (ton/fed.) after applying pulse technique with 4 pulses at 100 % from IRa under subsurface drip irrigation, recording an increase 40%.(4)Avoid using pulse technique at 50% fromirrigation requirementsbecause,small amount of irrigation water with more pulses with increasing in time-off will concentrate the salts around the plant especially under surface drip irrigation hence high decreasing in the yield of potato.(5)WUE potato increased from 1.59 (kg/m3) under CDI to maximum value, where it become 2.62 (kg/m3) after applying pulse technique with 4 pulses at 75 % from IRa under SSDI, recording an increase 65%, this mean that we can save 25% of actual irrigation requirements per season which equal 679 m3 from irrigation water.