Physical methods for soil disinfestation in intensive agriculture: Old methods and new approaches

Physical soil disinfestation is worldwide mainly applied in protected cropping systems or in small-scale intensive field crops. Continuous cropping of monocultures or different host plants for the same pest or pathogen often leads to heavily infested soils which forces growers to disinfest the soil thoroughly. The oldest method is steam sterilization which is applied for more than a century. In the 1970s hot water treatment of soils was developed in Japan. Hot water is applied to the soil surface to raise soil temperatures to lethal levels. Since the 1980s inundation became a new method in the Netherlands and is applied in bulb cultures. This so-called flooding of soils creates anaerobic soil conditions in which toxic compounds like greenhouse gases are produced. A new approach in soil disinfestation in the current century is hot air treatment which is developed in Israel. The method is based on blowing extremely hot air into soil particles which are thrown above soil surface into a heat chamber by a rotary spading device. In the Netherlands renewed interest has started in radiation of soil with micro waves. Radiation of soil or other substrates has been studied for decades. The mechanism is that the heat produced by radiation is lethal to pathogens and pests. Anaerobic soil disinfestation (ASD) with incorporation of fresh organic matter in soil is a method developed in the Netherlands. A new and promising Dutch development in ASD is the application of defined products. Advantages and disadvantages of all methods are presented in this paper