The gardeners have to deal with many unknowns, from unpredictable weather to various pests, viruses, and fungi that pose a danger to plants. Some risk factors cannot be controlled, such as rainfall management, but it is quite possible to improve the quality of the soil.
Soil sterilization is a method that is recommended if the crops in the garden have been exposed to diseases or an invasion of pests wintering in the soil in the last season. If there are no such problems, sterilization may do more harm than good, since it works not only against harmful but also beneficial organisms from microbes to earthworms.
The purpose of soil sterilization is to reduce the risk of potential harm from pathogens of common diseases (Verticillium wilt, fusarium, various root rot), from nematodes, larvae of insect pests, and weeds.
The principle of the method is based on sanitizing the soil using high temperatures. In the case of seedlings, when you decide to sterilize the soil for houseplants, a simple microwave or oven would do, but garden soil needs a different method for obvious reasons. Now we are going to tell you about the best soil sterilization methods.
Important note. Do not apply fertilizer before sterilizing the soil!
How to Sterilize Soil: 8 Effective Ways
Sterilize Soil in the Microwave
The microwave oven heats the water and turns it into steam, which in turn disinfects the soil. You can warm it up in a plastic flower pot (but considering the nuance which is discussed below) or in a glass container. It is not recommended to warm up the ground in its original packaging. Most plastic packaging and utensils (except for special ones) are not designed for heating and release harmful substances when the temperature rises.
The microwave power is average. Processing time depends on the amount of soil is 10-20 minutes.
It should be taken into account that moisture leaves the soil along with the steam, therefore, before the procedure, you need to additionally pour a small amount of water into the container. It is also advisable to cover the container with a lid.
How to Sterilize Soil with Boiling Water?
One of the most common ways to pasteurize potting soil is that does not require any knowledge and training. Pour a small amount of soil with boiling water (boil the water separately in a kettle). Cover with a lid and go about your business. The procedure is over when the soil has completely cooled down.
The advantage of the method is that after cooling down, you can already plant seeds or seedlings in such soil.
Steam Calcining the Soil
Another good way to sterilize potting soil with boiling water. This method requires a large pot. It is necessary to pour water into it and put it to a boil. Put a rag or cheesecloth in several layers in a sieve (so that the grains of sand do not pour through the holes) and pour the soil.
As soon as the water boils, you need to place a sieve with soil over the pan. Cover the sieve with a lid to create a steam effect. The procedure lasts from 30 minutes to 1 hour, depending on the volume of the soil.
After the procedure, it is necessary to let the soil cool down. To enhance the effect and further prevention, you can add ash or charcoal powder to the soil.
For a healthy harvest to be every year, gardeners recommend adhering to crop rotation. If you have such an opportunity, then completely replace the soil in the beds and the greenhouse. Unfortunately, this method is not always possible as it requires a lot of costs. In this case, hydrogen peroxide would be your salvation. Once you have harvested the crop, immediately disinfect the soil to minimize possible damage from harmful microorganisms remaining in the soil. To do this, use the following composition: 20 tablespoons of hydrogen peroxide in 1 gallon of water.
It is especially important to disinfect the soil used for seedlings. The prepared soil is carefully spilled with a 3-6% peroxide solution, covered with foil.
Calcining the Soil in a Frying Pan
If you are considering this method, please note that it is time-consuming. But some florists carry out disinfection in this way.
Place a small amount of soil in a large frying pan. Warm up the soil, stirring constantly and periodically moistening it from a spray bottle. You can also add some ash or charcoal to the ground.
The advantage of this method is that all living creatures, fungi, and so on die. Disadvantage – it takes time.
How to Sterilize Soil Using the Sun?
Solarization is usually used to disinfect the beds. Solarization uses the sun’s ability to warm up the soil intensively and quite deeply. This is usually done using black (in cooler regions) or clear plastic (in southern regions).
Prepare the bed by raking rubbish and large lumps of dirt. You need to avoid the formation of air pockets between plastic and earth. So take a shovel and make a trench around the garden.
Carry out deep watering – 6 inches, take a plastic “blanket” and secure it tightly by lowering it into the trench, pressing down with heavy stones, or digging in the ground.
It would take at least 4-6 weeks to achieve the effect, so start as soon as the sun starts to bake, like in spring. Even if you don’t have the time and patience to fully solarize, you can warm up the ground for planting. It is believed that raising soil temperature helps to break down organics and ultimately increases the availability of nutrients to your plants.
Calcining the Soil in the Oven
Baking soil is another great method if you need to sterilize a small amount. To sterilize the soil in the oven, put wet earth on a metal sheet with a layer of no more than 2 inches and keep it in an oven preheated to 160-190 °F for half an hour. This method is also great if you need to disinfect sand for plants.
Attention! A higher temperature is dangerous for the soil: nitrogen is mineralized, beneficial microorganisms die and the soil becomes less fertile.
Sterilizing Soil with Formaldehyde
The last method on our list, but no less effective among the rest, is the use of formaldehyde. All you need is formaldehyde and water. Or rather, a mixture of them. To make it mix 1 part 38-40% formalin to 49 parts water. Next, you need to thoroughly saturate the soil with the resulting solution. Use 5 gallons of formalin per square yard. The main work is over! It remains only to wait until the soil becomes safe to use. This usually takes 20 to 40 days.
Sterilized soil is a very important point and perhaps the only way to grow healthy and strong seedlings. Processing the soil before planting seedlings allows you to destroy pathogenic bacteria, insect eggs, fungal spores, nematodes, and to protect against various diseases. There are many ways to sterilize the soil, for most of them what you can find at home would suffice. If you need to disinfect a small batch of soil, it is enough to use a microwave or oven. In case you need sterilization of a large amount of soil, then you cannot do without the help of the sun or chemicals. In general, whichever of the above methods you choose, the desired result is guaranteed to you. Well, we can only advise you to experiment and choose the most suitable one for you.
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