Archive for August, 2009

The thermal sterilization of soil

Monday, August 10th, 2009

Heat has been used to control pests and weeds since the very beginning of agriculture.

Until today fields are burned down in order to create and improve soil fertility. Ancient civilizations such as the Indians or the Egyptians also systematically used sun radiation on irrigated agricultural soil to disinfect and revive arable land.

At the end of the 19th century the application of heat for soil sterilization is documented whereas two methods were developed simultaneously: the roasting of agricultural soil over an open fire and the steaming of soil with water vapor.

At the beginning steam was induced into the soil through drainage pipes. Later steaming hoods and harrows were used. The development of heat resistant sheets made the treatment of large areas with steam easy to handle.

The chemical sterilization of soil

Monday, August 10th, 2009

Chemical compounds for soil sterilization are easy to use and need little time for application.
Modern compounds have a relatively low effect range, only one or a few specific diseases or pests are overridden. Furthermore the application of chemical agents always comes with a long period of rest which is necessary to degrade or flush them out.

In particular if chemical means for soil sterilization are not applied properly harmful residues might stay in the soil and concentrate in plants which have still unknown effects on plants and man.
Besides the risk of resistance formation can not be ruled out when applying chemical agents which can even aggravate the symptoms of a disease.

Due to the uncertainty of bad side effects chemical agents for soil sterilization should only be applied very carefully, in particular when it comes to vegetable foods.

Soil sterilization against soil born diseases in agri- and horticulture

Monday, August 10th, 2009

The intense cultivation of agricultural crops challenges nature, since it has a negative impact on the biological equilibrium and strongly promotes the spread and growth of organisms harmful to plants. The culture of resistant high-yielding varieties alone does not solve the issue.
Therefore plant protection and pest control is essential in order to ensure high yields and guarantee the food supply of a steadily growing world population.

Thus soil plays a central role. Under extensive use soil is disabled to control pests though its balanced biological activities. In particular in green houses, soil is exposed to many different diseases which leads to an increased occurrence of wither and root sicknesses, nematodes and weeds.
Soil sterilization is a highly effective treatment method in the area of plant protection.
Two different methods are in use at present: The chemical and the physical/thermal treatment of soil.