Inhibition of root penetration in subsurface driplines by impregnating the drippers with copper oxide particles

Clogging of subsurface drip irrigation (SDI) systems by root penetration into the emitters results in inappropriate water supply, increased replacement rates of SDI systems and increased costs. We found that impregnation of SDI drippers with copper oxide particles inhibits root penetration very significantly. The inhibition of root penetration varied from 24 to 76 % of the control (60–80 % intrusion) depending on the copper oxide concentration of the drippers. The root penetration inhibition was demonstrated at two water flow rates, of 1 and 3.5 l/h, and with new and used drippers after 1750 irrigation hours. Inhibition of root penetration occurred also if sewage water was used. The inhibition of root penetration into drippers was demonstrated with lettuce and tomato plants and reached similar efficacy as compared to the widely used herbicide Stomp® root penetration inhibition treatment. The amount of copper that leached into the water was below detection limit (less than 0.006 ppm). No loss of copper oxide particles was detected in drippers through which 3350 l of water was passed (an amount of water that typically passes in SDI systems during 3–4 years of use), as determined by scanning electronic microscope and X-ray photoelectron spectrum analysis.