RU2125355C1 - Soil disinfection method - Google Patents

Abstract

FIELD: agriculture. SUBSTANCE: method involves exposing soil to electromagnetic microwave field; heating soil to temperature of 64-70 C at heating rate of 0.04-0.5 C/sec with following thermostatic control for at least 180 sec without supplying heat-carrier. Soil cooling rate must not exceed 0.05 C/sec. EFFECT: increased efficiency and reduced disinfection process time. 1 dwg, 3 tbl, 1 ex

Description

 The invention relates to agriculture and can be used for disinfection of the soil.

 A known method of disinfecting the soil (A. S. 485720, USSR, MKI A 01 B 47/00 - Published in B. I. N 36, 1975), including warming the soil with hot water, followed by short-term exposure to alternating current.

 The disadvantage of this method is the significant investment of time in heating the soil with water.

 A known method of disinfecting the soil (A.S. 719523, USSR, MKI A 01 B 47/00 Publ. In B.I., N 9, 1980), including moistening and subsequent exposure to the soil by electric current during soil vibration before and in disinfection process.

 The disadvantage of this method is the significant investment of time in tillage by electric current.

 The objective of the present invention is to increase the effectiveness of disinfection of the soil, which is expressed in reducing the time of exposure.

 This problem is achieved by a technical solution, which is a new way of disinfecting the soil, including heating the soil with a high frequency electromagnetic field.

The invented method differs from the known [2] in that the soil is heated to a temperature of 64 - 70 degrees Celsius ( ^o C) at a rate of 0.04 - 0.5 ^o C / s with temperature control without supplying a coolant for at least 180 s at a speed soil cooling not more than 0.5 ^o C / s.

 The proposed method has significant differences, since the applicant has not found other known technical solutions with similar features.

When implementing the method, the distinguished features identified in combination with other signs provide a positive effect, which consists in saving time spent on disinfection with an electromagnetic field of superhigh frequency (microwave) due to the intensification of soil heating to a temperature of 64 - 70 ^o C at a speed of 0.04 - 0, 5 ^o C / s with temperature control of the heated object without supplying a coolant for at least 180 s at a cooling rate of not more than 0.05 ^o C / s.

 Example. During the experiments, a sample of greenhouse soil 2 was placed in the chamber in the form of a rectangular waveguide 1 with a cross section of 45 x 90 mm, in which microwave energy was propagated (see drawing). To ensure the necessary cooling rate, the soil was placed in a container 3 of fluoroplastic and covered with a cover 4.

 Ftoroplast is an almost perfect dielectric with low microwave losses and has a low coefficient of thermal conductivity. The latter circumstance allows you to reliably insulate the soil from the environment, and its cooling rate is determined by the thickness of the container walls.

In this example, a microwave source was used with the following parameters:
- frequency - 2450 MHz
- power - 250 W
The object of the microwave exposure was a greenhouse soil infected with the pathogen Fusdrium t. Cp. Diomthi. Determination of the degree of infection of greenhouse soil was carried out in accordance with the methodological materials Bilay V. Methods of experimental mycology. Kiev. Naukova Dumka, 1973. In this case, the indicator of the degree of infection is the number of conidia-forming units (CFU) of the fungus per gram of air-dried soil. The following infection rate scale was used:
- the soil is partially infected if the CFU is not more than 500;
- the average degree of soil infection is characterized by a content of from 500 to 2000 CFU;
- highly contaminated soil contains over 2000 CFU.

 The microwave heating rate of greenhouse soil 2 in waveguide 1 depends on its moisture content. The higher the humidity, the higher the microwave heating rate of the greenhouse soil. Therefore, the lower and upper boundaries of the microwave heating rate are determined respectively by the heating rate of dry soil (15%) and moist soil (66%), see table. A.

 The results of microwave treatment of greenhouse soil of varying degrees of infection without temperature control (cover 4 on container 3 is missing, see drawing) are presented in table. 1.

 However, the effect of disinfecting the soil can be achieved in less time with a lower final temperature of microwave heating, if the greenhouse soil is thermostated (the container 3 is covered with a lid 4, see drawing). This is confirmed by the results of the experiments in table. 2.

From a comparison of the table. 1 and 2 it follows that due to thermostating for at least 180 s at a cooling rate of greenhouse soil of not more than 0.05 ^o C / s, the disinfection effect is achieved at a final microwave heating temperature of 67 +/- 3 ^o C. Comparison results of the found regime Microwave disinfection of infected greenhouse soil with exposure to electric current according to [2] are given in table. 3.

 As follows from the table. 3, in comparison with the treatment with electric current [2], the proposed method of disinfection with a microwave field will reduce the time of exposure to the soil by an average of 8 times.

Sources of information
1. A.S. 485720, USSR, MKI A 01 B 47/00 - Publ. in B.I., N 36, 1975.

 2. A.S. 719523, USSR, MKI A 01 B 47/00 - Publ. in B.I., N 36, 1980.

 3. Bilay V.I. Methods of Experimental Mycology - Kiev: Naukova Dumka, 1973.

Claims (1)

A method of soil disinfection, including heating the soil with an electromagnetic field of ultra-high frequency, characterized in that the soil is heated to a temperature of 64 - 70 ^o C at a rate of 0.04 - 0.5 ^o C / s with temperature control without supplying a coolant for at least 180 s at the cooling rate of the soil is not more than 0.05 ^o C / s.

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