Effect of Capillary Rise in Subsurface Drip Line Irrigation on the Depth of Sowing

Subsurface drip irrigation with an efficiency of over than 90 percent is one of the method for row crops that can be used for cereals and trees. In this regard¡ the present study was done to investigate the distribution of moisture and capillary rise of water in a silty clay soil with subsurface tape drip irrigation in the city of Rasht in the summer of 2012. The experiment was carried out with three irrigation volumes of 10¡ 15 and 20 liters and three tape installing depths of 10¡ 20 and 30 cm with three replications¡ in the Agricultural and Natural Resources Research Center. Capillary rise of wetting front in tape installing depths of 10 and 20 cm for all volumes of irrigation water from zero to 10 cm layer of soil moisture reached to field capacity moisture level and covered the all optimal planting depth of seed. With 30 cm depth installation and 10 liters of irrigation volume¡ wetting front capillary rise was not reached to zero to 10 cm soil layer and in volumes of 15 and 20 liters of irrigation volume¡ capillary rise of wetting front reached to 6 to 7 cm beneath the soil surface. Best tape installing depths was 10 and 20 cm¡ but because of interruptions to tillage¡ tape installation depth of 30 cm with an appropriate irrigation volume or with light irrigation for germination in the case of dry springs¡ is recommended.