Soil steam sterilization

Soil steam sterilization is a farming technique that sterilizes soil with steam in open fields or greenhouses. It is being used as an alternative to bromomethane, whose production and use was curtailed by the Montreal Protocol. "Steam effectively kills pathogens by heating the soil to levels that cause protein coagulation or enzyme inactivation." [http://www.epa.gov/ozone/mbr/casestudies/volume3/steam3.html EPA] Steam as an Alternative to Methyl Bromide in Nursery Crops]

Benefits

The claimed benefits include: [ [http://www.alvanblanch.co.uk/soil%20sterilization%20cover.pdf alvanblanch] SOIL STERILIZATION SYSTEMS]
#Destroys all insects, larvae, pathogens and cryptogamic diseases.
#Enhances soil - with improved release of organic nutrients.
#Destroys all weed, seeds and roots.
#Improves crop germination.

History

"Soil steam sterilization was first discovered in 1888 (by Frank in Germany) and was first commercially used in the United States (by Rudd) in 1893 (Baker 1962). Since then, a wide variety of steam machines have been built to disinfest both commercial greenhouse and nursery field soils (Grossman and Liebman 1995). In the 1950s, for example, steam sterilization technologies expanded from disinfestation of potting soil and greenhouse mixes to commercial production of steam rakes and tractor-drawn steam blades for fumigating small acres of cut flowers and other high-value field crops (Langedijk 1959). Today, even more effective steam technologies are being developed."

Negative Pressure technique

"Negative Pressure technique generates appropriate soil temperature at a 60 cm depth and complete control of nematodes, fungi and weeds is achieved. In this technique, the steam is introduced under the steaming sheath and forced to enter the soil profile by a negative pressure. The negative pressure is created by a fan that sucks the air out of the soil through buried perforated polypropylene pipes. This system requires a permanent installation of perforated pipes into the soil, at a depth of at least 60 cm to be protected from plough." [ [http://www.fao.org/DOCREP/004/Y1809E/y1809e07.htm FAO] Global report on validated alternatives to the use of methyl bromide for soil ]

ources and notes