Archive for the ‘Soil Sterilization’ Category

STEAM CONTINUES TO SUBSTITUTE METHYL-BROMIDE IN SOUTH AFRICA

Sunday, December 2nd, 2012

A large floriculture enterprise near Pretoria, the capital of South Africa, has completed its changeover to hot steam as a soil sanitising medium in greenhouses. Previously they used 40-50 gram hazardous plant protection chemical per square metre – with good results.

However, the prohibition of methyl-bromide by the Montreal Protocol and the requirement to put it into effect in developing countries by 2015 at the latest necessitated to re-think this conventional method.

Mr Marten Barel, a worldwide active specialist in horticulture, found an alternative method in which hot steam is used.

The system including steam boiler was supplied by MSD GmbH (Durbach, Germany) on the basis of the concept developed by Mr Marten Barel.

In the system, a sandwich-type steaming technology is used. The steam is immediately injected into the soil to 20cm depth via hollow pins of a spiked hood made of load-resistant aluminium. Then an average temperature of 80°C is achieved in 6 minutes. This means a complete sanitisation. After the steaming, the soil is free from weeds, weed seeds and soil-borne pests and pathogens across all the 20 cm depth.

Spiked hood with mechanisms for easy lifting-up, lowering and moving

Spiked hood with mechanisms for easy lifting-up, lowering and moving

The steaming process takes place only under glass. The special steaming hood is operated manually, i.e. moved every 6 minutes (due to low labour cost, the company did not want to purchase a semi-automatic solution with hydraulic components). The steamed surface is promptly covered with a sheet to keep the heat in the soil. In this system, the performance is 600 sq. m a day. The energy consumption is about 0.65 l heating oil per square metre. The result is very favourable for the company since especially very sensitive plants, e.g. Lisianthus, positively react on soil steaming.

SOUTH AFRICA DISCOVERS THE EFFECT OF HOT STEAM AS SUBSTITUTION OF METHYL BROMIDE

Tuesday, September 25th, 2012

Timbali Technology Incubator is the first agriculture enterprise in South Africa which uses a steaming boiler (from MSD / Moeschle) to do completely without the harmful soil- chemical methyl bromide (MeBr) and to use hot steam to disinfect the soil and substrates for cultivation of new plants.

Methyl bromide is a smell-free and colour-free gas. It is used as a soil fumigant at agriculture, floriculture, horticulture and olericulture companies and also at the agriculture enterprise Timbali to control weeds and to eliminate soil-borne pests and pathogens.

Timbali Technology Incubator is the first agriculture enterprise in South Africa which uses a steaming boiler (from MSD / Moeschle) to do completely without the soil disinfecting chemical methyl bromide (MeBr) hazardous to health and harmful to the environment. Instead of it, for cultivation of new plants, the company uses hot steam to clean the soil and substrates from weeds, pathogens and pests.

Methyl bromide is a smell- and colour-free gas, which was also previously used as a soil fumigant against weeds, soil-borne pests and pathogens at Timbali, especially for cultivation of flowers and vegetables.

The use of methyl bromide had to expire till January 2005, because it enormously endangers the ozone layer of the stratosphere and is very risky for human health. However, in this respect, Africa still lags behind and was given a grace period for implementation of the MeBr prohibition till 2015. As soon as this period has elapsed, the use of this soil fumigant is also prohibited in Africa according to the Montreal Protocol.

Hood steaming at Timbali, South Africa

Hood steaming at Timbali, South Africa

Being the first company which uses a MSD steam boiler for sanitisation of soil in gardening, Timbali has demonstrated its pioneering spirit and is supported by its partner Eskom.

Mobile high-performance steaming boiler of MSD GmbH (Durbach, Germany) using 200°C superheated steam

Mobile high-performance steaming boiler of MSD GmbH (Durbach, Germany) using 200°C superheated steam

Some representatives of agriculture enterprises visited Timbali at 29th of August 2015 to see the new machine and the introduced steaming technology (mainly hood steaming). Mr Marten Barel, the expert in steaming technology, demonstrated this steaming boiler and explained all system advantages and functions to the visitors.

Now Timbali continues to make this technology public in South Africa and thereby supports the development of small agriculture business.

Video of introduction of the steaming technology at Timbali (click here)

Steam is also a hot thing for vine plants

Monday, April 30th, 2012

Last year the Service Center for Rural Areas (DLR) Rheinlandpfalz (Rhineland-Palatinate) has steamed vineyards for the very first time, in order to research the effects of this soil sterilization method on young vine.

Recently the results were presented. It was shown, that steam significantly increases the growth of plant shoots:

Steaming significantly increases the growth of vine shoots (Source: DLR Rhineland-Palatinate, Schifferstadt)

Steaming significantly increases the growth of vine shoots (Source: DLR Rhineland-Palatinate, Schifferstadt)

It remains to be clarified, if hot steam significantly improves the sprouting of vine. In particular where soil is both highly contaminated with diseases (such as fungus, bacteria, nematodes) and highly affected by soil fatigue, steaming could be developed to a profitable sanitation method for vine nurseries.

Under the leadership of Matthias Zink the DLR in Schifferstadt started a research study together with the steaming specialist MSD (Möschle-Seifert-Dämpftechnik – Steaming Technology) this year. Results are expected next year.

More research trials with steam at DLR & Agroscope

Friday, March 9th, 2012

Also in 2012 renowned research institutes plan to do more research on hot steam..

The Service Center for Rural Areas (DLR) Rheinlandpfalz (Rhineland-Palatinate) will do more field studies in tree nurseries in the end of March 2012. In the process the focus will be on the optimization of steaming methods, in order to find out the most effective use of steam.

The preferred method is Sandwich-steaming. Hereby steam is injected simultaneously from the surface and in the depth through a steaming hood with pikes. The goal is the efficient use of hot steam at cost less than 5,000 EUR per hectare.

Besides the DLR, the Agroscope Institute of the University of Wädenswil in Switzerland will do another study on steaming. Hereby hot steam is used to kill a special kind of grass.

This grass has become a pest in Switzerland and causes increasing problems in agriculture as it hampers the growth of cultures. Hot steam shall help to sanitize these infested areas.

Hot steam finds its way into Kenya

Saturday, November 20th, 2010

Even where labor and land is cheap, hot steam is needed to sterilize arable land. In September 2010 a big Dutch flower grower started to use its steam generator in its Kenyan green houses.

Area steaming in Kenia – Flower growing

Area steaming in Kenia – Flower growing

Steam is mainly used to sterilize volcanic substrate so the material can be reused several times. The substrate gets steamed in steam boxes which are equipped with a vacuum steaming system. Vacuum steaming systems are highly energy efficient. The steam generator was manufactured by MSD GmbH, Durbach.

Soil decontamination with hot steam

Tuesday, December 22nd, 2009

Decontaminating and disinfecting soil with hot steam has been applied for more than 100 years and is well proven. The Swiss Friedrich Miescher Institute in Basel has made use of this method.

The institute will decontaminate the soil of several green houses completely without chemicals. The goal is to free soil from sproutable plant parts such as seeds and roots as well as restore the original condition of the soil before cultivation without residues of chemical products. Hence steaming was the first choice.

A contractor is responsible for steaming. First soil is loosened down to 20 cm depth, after that the area is gradually covered with steaming sheets which get weighted. Steam generated with a low pressure steam boiler, is induced via a steam injector underneath the sheets.

After 2-4 hours of steaming the desired results are achieved: The soil is completely sanitized and without weeds and diseases.

The danger of recontamination

Sunday, August 23rd, 2009

A special source of danger of reinfecting soil with pathogens after steaming is deeper soil. Depending on the root depths of the planted culture, phytopathogenic organisms can reach and contaminate deeper layers of soil. It can happen that steamed higher layers of soil are reinfected by such deep lying pathogens.

Hence when soil is heavily contaminated it is recommended to take soil samples from different soil depths depending on the root depth of the planted crop and check on diseases in order to identify the necessary steaming depth.

Furthermore the injection of beneficial active micro organisms after steaming into the soil can significantly strengthen the resistance against intruding pathogens and immensely inhibit recontamination.

The danger of recontamination on the surface by carry over e.g. when using foreign substrates or planting contaminated plants can be limited through the injection of beneficial microorganisms.

Reactivation of decontaminated soil

Sunday, August 16th, 2009

After decontamination of soil with hot steam a quick reactivation with microorganisms takes place. At the beginning, harmful as well as beneficial organisms resettle. But beneficial bacteria and fungi find better conditions and gain a considerable head start. In general beneficial organisms will prevail. The quick revival can be traced back to many different reasons: Most important is low competitive pressure from other species as well as the availability of nutrients and other beneficial chemical substances which were dissolved by steaming.

The first wave of reactivation comes from heat resistant species e.g. spore forming bacteria. The effect of heat shock on the termination of latency is well known in particular for bacteria and fungi. Furthermore microorganisms from deeper areas which were untreated move up.

Furthermore germinable spores arrive by air, most of them come from fungi. In most of the cases a new barrier against the spread of pathogens is formed quickly and naturally.

In rare cases, pathogenic organisms may prevail after steaming due to unbeneficial circumstances, which can lead to enormous damage. In order to prevent the spread of pathogenic organisms it’s recommended to seed beneficial microorganisms into the soil right after steaming.

Water vapor for soil steam sterilization

Saturday, August 15th, 2009

In contrast to other agents (such as air) water has the ability due to its high specific heat to absorb a tremendous amount of energy at a constant temperature of 100°C when transforming from water to steam. This energy is released in the soil for disinfection.

As a result this method obtains a particularly high degree of efficiency with which all organic pathogens are killed at sufficient time of exposure.

Due to the relatively low temperatures of just up to 100°C during the condensation process, soil is prevented from damage. In contrast to the usage of dry heat (e.g. hot air) soil can not be burned and its fertility harmed.
Compared to other chemical agents, water vapor has a comprehensive sterilization effect on soil. All organic pathogens are affected by the humid heat and even killed after sufficient exposure.

Chemical agents only partially take effect, since they are focused on single pathogens only. If soil suffers from different diseases a chemical cocktail is necessary which can lead to enormous risks for the health and environment.

The usage of dry heat (Roasting) for soil sterilization

Monday, August 10th, 2009

Even by burning down arable land, heat reaches down to up to 10 cm depth. In early times this method was used for intensive farming, in particular on plantations to cure root diseases and control weeds. At the beginning of the last century soil roasters were used in which substrate was filled and heated over open fire.

Today hot air devices are used for dry soil heating.

With dry soils the roasting method can lead to heat damages and destroy the organic components of the soil, which are essential for the growth of the plant. Therefore one has to pay attention that the soil is sufficiently humid and treatment does not last too long when using dry heat.