Current Agriculture: Soil sterilization

Soil sterilization is the act of killing or destroying the action of diseases causing organism that are present in the soil without causing harm to other plants. In other words, soil sterilization is a process by which chemicals are used to render or arrest soil living organism that are capable of destroying plants and causing disease in the soil to be inactive, impotent or unproductive. These chemicals are selective in nature, that is, when they are used, they only affect particular diseases for which it is meant for, without causing harm to the other organism that inhabit the soil.

Numerous methods of soil sterilization have been used to sterilize the soil or inhibit microbial activities in the soil. The method used often will depend on the facilities available and the design of the particular experiment. Sterilization usually alters the chemical and physical properties of soil in addition to eliminating organization. In soil sterilization, the following methods could are employed;

Steam method: In soil sterilization, steam method or auto claving are widely used to sterilize soil samples as the equipment is readily available in most research and teaching laboratories. Soil is steamed at 121⁰c for a minimum of 20 to 30mins but generally longer than one hour. The length of time should be increase when larger amount of soil are sterilized. The soil can be autoclaved in glass beakers, glass Petri dishes, and stainless steel trays with lid jar. The container use for this activity can be covered with aluminum foil. The soil should be spread out in thin layer to allow for penetration of steam during the auto clave cycle.

Microwaves: This is another method used for the sterilization of soil. Microwaves cause water in the soil and cells to absorb heat which result in high temperature that kills the soil organism. For this reason, the lethal action of micro waves is higher in moist soil than that of dry soils. Microwaves are rarely used to treat soil in micro biological research.

Y – Irrigation: The main advantage of irrigation is that, mineral disturbance of soil occurs during the sterilization process. Soil adjusted to the desired water content for experiment are placed in sealed polythene soils and irrigation at 2.5 Mrad at the rate of 2 Mrad in one hour. After irradiation, the soils are maintained under sterile conditions to prevent subsequent contamination by non-aseptic, tending irradiation can cause deploymarization of carbohydrates like cellulose and create free hydrogen and hydroxyl radicals that are reactive as reducing and oxidizing agents and clave c-c bonds.

Chemical method: Chemical methods of soil sterilization include the following;