Soil borne pathogens and pests make life difficult for plants. Viruses, bacteria, fungal spores and pests lurk almost invisibly in soil or compost as a massive threat to successful cultivation. So that sowing and cultivation are not doomed to failure, knowledgeable home gardeners subject the substrate to an environmentally friendly soil disinfection with the help of heat and steam. Read here why it is worth the effort to make soil sterile. A tried and tested guide explains how to properly steam compost.
Why should home gardeners sterilize soil?
A broad spectrum of soil-borne and root-infecting pathogens turns compost soil into a fatal source of infection. Numerous viruses use non-rotted plant residues for explosive reproduction. Some particularly bold bacteria can survive for a long time without plant residues in the soil and lurk for suitable host plants. Last but not least, fungal spores use plant remains in the compost as a starting point for infestation of the plants used. The myriads of weed seeds or pest eggs that have taken root in the substrate are in the same direction.
Those who ignore the risk of contaminated compost soil are leaving their seedlings and plants defenseless against the risk of infection by diseases or pests. Without prior treatment, vigorous weeds have easy time and overgrow young plants in next to no time. By home gardening the earth
Ornamental and vegetable plants can develop vital, healthy and undisturbed by making them germ-free with natural means.Moist heat kills pathogens
Home gardeners who are close to nature have banned chemical poisons from the garden and give priority to environmentally friendly methods of plant protection. This motto also applies to the destruction of pathogenic pathogens and weed seeds in soil for sowing, bedding and planting in pots. Viruses, bacteria, fungal spores and the like have nothing to oppose moist heat. An investigation into the markedly heat-resistant fungal spores of Fusarium oxysporum revealed where the so-called thermal inactivation point lies. Soil infected with the pathogens was germ-free after heat treatment at 80 degrees Celsius. Experts conclude from this that most harmful pathogens will stretch their arms at this temperature.
A temperature of 80 to 100 degrees Celsius alone is not enough for comprehensive thermal soil disinfection. The desired killing effect is only achieved in combination with moisture. When dry, the germs to be controlled can withstand much higher temperatures without damage. The third factor is a sufficiently long exposure time of around 30 minutes. Beyond this time, the damping should not be continued in order to keep negative side effects to a minimum. It should be noted that useful microorganisms can also be affected by moist heating.
Earth damper in wheelbarrow format
So that allotment gardeners can make homemade compost and bought-in soil sterile, the earth steamer is available in wheelbarrow format. The device is tailored to the needs of the home garden in order to disinfect up to 70 liters of substrate from pathogenic germs of all kinds. The complete set consists of a wheelbarrow with a steam generator, test thermometer, grate, jute filter and lid. The attainable steam temperature is 80 degrees Celsius and therefore requires the minimum requirement to render pathogens, pests and weed seeds harmless.
If the purchase price of 729 euros for a BEGA steaming wheelbarrow is too high, you can use a BEGA steaming pot. You can use it to sterilize up to 25 liters of compost at 80 degrees Celsius, provided a heat source is available, such as a fireplace, gas or electric heater. For 159 euros you get an aluminum pot with lid and perforated sheet made of stainless steel. In order to decontaminate up to 150 liters of soil or compost germ-free, you have to dig deep into your pockets. An appropriately sized steam wheelbarrow costs a whopping 1,600 euros.
Note: Thermal composters are not suitable for soil decontamination by means of steam. Although high temperatures can develop inside, numerous ventilation slots prevent the necessary steam from building up. Oxygen is vital for microorganisms and microorganisms that take care of the decomposition of the organic material.
Steaming instructions
If an earth steamer is ready, you can sterilize soil and compost within a few minutes. Use the following steps to operate the device correctly:
- Fill with water, matched to the size of the wheelbarrow or pot
- Place the jute filter on the integrated grid
- Loosen up soil or compost and fill in
- Put on the cover
- Switch on the device or place the pot on the heat source
- Steam for 30 minutes and keep an eye on the temperature
After half an hour of moist heat at 80 degrees Celsius has acted on the substrate, not only are everyone
destroys pathogens. In addition, the earth is as open as after months of cultivation by busy soil organisms. Steaming makes nutrients and trace elements available to the plants in a timely manner, from which seedlings and young plants benefit immediately.Tip: When compost is steamed, effective nutrient compounds are formed quickly. When growing young plants, this concentrated charge of plant energy is not always desirable. Enrich the sterilized soil with sand or coconut fibers to at least one third to make it emaciated.
Steam the compost in the oven
For balcony gardeners, investing in a steamer is not always worthwhile. In order to make soil or compost germ-free, the oven is quickly converted into an earth steamer. In these steps you can successfully disinfect substrate in the kitchen:
- Fill fireproof bowl or deep baking tray 10 cm high with soil or compost
- Caution: Do not sterilize orchid soil in the oven because of the risk of fire
- Spray with a fine shower head
- Lay the aluminum foil or lid loosely on top
- Preheat the oven to 80 to 100 degrees Celsius
Slide the container or baking tray into the middle rail of the oven. Lock the door, because the oxygen supply from the outside prevents the formation of steam. After 30 minutes, turn off the oven, open the door and let the sterilized soil cool down. Are you bothered by the unpleasant smell that compost develops when steaming in the kitchen? Then put the soil in a roasting tube, which you put tightly closed on the baking sheet.
Sterilize small amounts in the microwave
Impatient home gardeners use the microwave to sterilize small amounts of substrate within minutes. To do this, put compost in a microwave-safe container. Spray the substrate with water beforehand and loosely put a lid on. At 600 watts, the process is completed within 10 minutes. Open the microwave so that the container and the steamed earth cool down.
