Destruction of weeds by pulsed high voltage discharges

Abstract

In order to replace the use of chemicals for weed control, the destruction of weeds by pulsed high-voltage spark discharges has been investigated. Small weeds, 4-6 cm in height and of 1-3-mm stem diameter could be destroyed by one discharge with its electrical energy of 135 mJ. The stems and roots of weeds were damaged. The electrical resistance of these small weeds was 1-2 M Omega and decreased to 100-200 k Omega after the discharge. Microscopic observations indicated that stem and root cells were damaged by the spark discharge. Large weeds in fields (80-120 cm in height and 10-15 mm stem diameter) could also be destroyed effectively using a pulsed voltage source designed for field use which generated a voltage with a 15 kV crest value, a 30 Hz frequency. and discharge energy of 2 J. Since the spark discharges take place from the electrode to a nearest or highest weed, the discharge can selectively destroy weeds which grow faster. The use of pulsed voltage can restrict the electrical energy of the discharge below the incendiary level. The spark discharge takes place not only between the electrode and the leaf, but also between the roots and soil. Nitrogen can be fixed around the roots. Sterilization of soil around the roots can also be done by the discharge. >