Response of “Lollo Bionda” lettuce to drip and porous pipe irrigation

Under the impression of changing rainfall patterns, agriculture in Germany faces increasing drought stress problems and water saving irrigation is gaining importance in the agricultural practice. Porous pipes for subsurface irrigation are an innovative method which is promoted as a water-efficient way to apply irrigation water. In the present study “Ecotubes” porous pipe irrigation was used for irrigation of “Lollo Bionda” lettuce at the University of Weihenstephan-Triesdorf in Southern Germany and compared to state-of-the art drip irrigation both at surface and sub-surface installation. Four treatments were compared during three experimental cycles “summer”, “late summer” and “autumn”: (a) drip irrigation in standard surface installation (control), (b) sub-surface drip irrigation, (c) porous pipes at standard operation and (d) porous pipes at very low pressure. The treatments were compared in terms of crop development, irrigation water applied, yield and water use efficiency (WUE). The highest yields were observed at low pressure irrigation with porous pipes (39.4 t/ha) followed by subsurface drip irrigation (36 t/ha). However, it was shown that the total amount of irrigation water applied, rather than the irrigation method determined the overall yield level. Subsurface irrigation methods had the highest WUE with 50.5 and 49.6 kg/m 3 for porous pipes and subsurface drip irrigation, respectively. The study shows that subsurface micro irrigation systems are good for water saving horticultural production in Germany. The use of porous pipes is a good option for subsurface irrigation depending on the technological development in terms of installation and recovery, and the durability of the material.