Soil Sterilization (growing, bugs, grass, containers)

[Philip T]

Anyone here know much about soil sterilization?

It is supposed to be handy for killing pathogens, weed roots, and weed seeds that may exist in the soil.

Looked up some info and found that heat, steam, microwaving, and few other methods seem to do it.

And I follow it is popular for greenhouse or indoor plants, and is done sometimes in limited small garden areas. I found at least a couple of interesting sites on the topic >>>

Wayne Schmidt's Soil Solarization Page

Start Seed and Transplants in Sterilized Soil

On my level of insanity . . . . I am thinking about doing or trying it on an acre or more, of past farmland that has sat fallow for at least 20 years in East Texas. It has grown up rather weed infested, as well as full of grubs that the wild pigs seem to love to dig up.

In older farming days, we would deep mold-board plow such an area (turns the soil and weeds completely over to about 10 to 12 inches) and leaves the green weeds to rot, at the bottom, and then sometime later, we would disk, drag smooth and then plant. Problem is that weed roots -- like crap grass -- that survive come up hard and choke out the desired plants. It also takes a long drawn out process and multiple passes of equipment.

I have tried roto-tilling sod like this before and that sod recovers and comes back strong and chokes out the new, desired plants. What I am considering is roto-tilling and then steam sterilization of the whole area.

Anyone have any tips, cautions, caveats, don't-do's, or unintended consequences to look for with soil sterilization?

[FOAD]

The common methods of soil sterilization listed everywhere on the Internet work well for small amounts of potting soil. This is because microwaving or baking in the oven are very inefficient and can be super smelly. Cooked soil is a smell that will attach itself to your furnishings, and linger.

The method I prefer, although it may not be the most thorough, is to sterilize the soil in a container outdoors with boiling water. Just boil water and pour enough into the container to get the soil damp and seal the container. Covering helps the steam to amplify the amount of soil you can process, especially if you agitate the container. One time I sterilize a 55 gallon drum of soil with this method, rolling the container along the drive to help the steam do its work.

If you have access to cheap fuel, perhaps brush piles or scrap wood, you can rig up a bunch of 5-gallon containers to boil and pour them all over this small field. If fuel is scarce, perhaps you could use a combination of boiled water sterilization AND solarization? Just pour the water in sections, and cover with your plastic, perhaps and that will amplify the steam.

Of course, this all depends on access to cheap fuel, but the boiling water applied liberally, it will do the work even in the cool Texas Winter weather, and you may be done in as little as a weekend.

Good Luck. Just BE CAREFUL!

Maybe you can report back your results?

[FOAD]

Originally Posted by Philip T

I have tried roto-tilling sod like this before and that sod recovers and comes back strong and chokes out the new, desired plants. What I am considering is roto-tilling and then steam sterilization of the whole area.

Rhizome based weeds are difficult to eliminate by roto-tilling. Constant, expensive roto-tilling will be required, because all the roto-tiller does is chop and spread the rhizomes. A faster way to defeat stubborn root systems is with RoundUp and roto-tilling. Preferably generic equivalents to RoundUp (just look for glyphosate as the active ingredient.) Follow the recommendations for WHEN TO APPLY, as this is the primary reason for wasted glyphosate applications.

The plastic solarization method is effective in eliminating weed SEEDS from your garden plot, because the seeds will sprout and die under the plastic. Exactly what you want to do! However, the rhizome of established weeds will survive solarization for extended periods, and multiple tillings.

Choose your methods. It all depends on how quickly you want to get the plot into production, and how much effort you want to apply.

[SCGranny]

Sterile soil is dead soil.
If you truly sterilize soil, you kill not only the weeds, rhizomes, roots, seeds, and 'bad' bugs and pathogens - but also the very things that make soil prolific and productive. Rot encourages healthy growth.

Full soil sterilization of an acre will require a lot of money and time, and still may not be as thoroughly done nor as beneficial as you think. Depending on your soil structure - and it varies from area to area, even in an acre! - sandy, loamy, clayey, surface vs subsurface, what it has in it as well as what it does not, what kind of water it receives/holds, what sort of temperatures and even winds it is subject to - these are all considerations. Before you do a single thing, take several test samples from several parts of the acre, and take them to your extension agent to have them tested - and ask what is done in your area for weed control, pest control, etc. They may be able to point you in a much cheaper and much more beneficial direction.

[azoria]

I remember watching this large scale soil sterilization on farm acreage in California years ago when a lot of cropland was being converted to vineyards. Apparently grape vines are susceptible to a host of soil born pathogens.

They covered the land with black plastic and let the plastic sit there all summer, superheating the ground for months. It was a strange thing to see, entire river valleys covered in black plastic.

You could try this? Cover your acre with black plastic and leave it there for the summer.

[Philip T]

Originally Posted by FOAD

The common methods of soil sterilization listed everywhere on the Internet work well for small amounts of potting soil. This is because microwaving or baking in the oven are very inefficient and can be super smelly. Cooked soil is a smell that will attach itself to your furnishings, and linger.

The method I prefer, although it may not be the most thorough, is to sterilize the soil in a container outdoors with boiling water. Just boil water and pour enough into the container to get the soil damp and seal the container. Covering helps the steam to amplify the amount of soil you can process, especially if you agitate the container. One time I sterilize a 55 gallon drum of soil with this method, rolling the container along the drive to help the steam do its work.

If you have access to cheap fuel, perhaps brush piles or scrap wood, you can rig up a bunch of 5-gallon containers to boil and pour them all over this small field. If fuel is scarce, perhaps you could use a combination of boiled water sterilization AND solarization? Just pour the water in sections, and cover with your plastic, perhaps and that will amplify the steam.

Of course, this all depends on access to cheap fuel, but the boiling water applied liberally, it will do the work even in the cool Texas Winter weather, and you may be done in as little as a weekend.

Good Luck. Just BE CAREFUL!

Maybe you can report back your results?

I have to score this a very simple and very clever approach. I should have all the free water we could care to use -- a free flowing creek is on the site, and there should be plenty of hot water, as well, since I am building a Solar Boiler for the site -- but I like your bonfire approach, as well.

I can see a couple other positives about your open container system over running it up to steam level, as well -- over 200 F degrees some bad things can happen, however, this direct hot water method should keep things near or below 200 F, as otherwise it will just boil away.

From what I have read, if you can get up to around 180 to 200 F, it only has stay at that range for around a 1/2 hour. I can drop 4 X 8 sheets of insulating Foam Board on the areas after I pass over them and pick them as I pass along on the next row.

Again, very clever. Thank you.

btw, I have started putting some photos, and layout map together and will do a webpage so anyone interested can follow along.

I am also having this discussion concurrently at LATOC, and they have had some different suggestions, as well -- that thread link is >>>

Soil Sterilization

[Philip T]

Originally Posted by FOAD

Rhizome based weeds are difficult to eliminate by roto-tilling. Constant, expensive roto-tilling will be required, because all the roto-tiller does is chop and spread the rhizomes. A faster way to defeat stubborn root systems is with RoundUp and roto-tilling. Preferably generic equivalents to RoundUp (just look for glyphosate as the active ingredient.) Follow the recommendations for WHEN TO APPLY, as this is the primary reason for wasted glyphosate applications.

The plastic solarization method is effective in eliminating weed SEEDS from your garden plot, because the seeds will sprout and die under the plastic. Exactly what you want to do! However, the rhizome of established weeds will survive solarization for extended periods, and multiple tillings.

Choose your methods. It all depends on how quickly you want to get the plot into production, and how much effort you want to apply.

I used Round Up a fair amount back when I grew SoyBeans in a now long ago Farming Life. We would get Bindweed (Morning Glory) growing up in the middle of a field, and the Round Up could knock it down, with minimum damage to the SoyBeans.

We are looking at getting an "Organic" Listing for this site, and from what I think I follow, the planting locations are supposed to Chemical Free for at least 5 years.

I think from what I have read, the Hot Water / Steam also takes out the weed seeds, but I will check and verify that.

[Philip T]

Originally Posted by SCGranny

Sterile soil is dead soil.
If you truly sterilize soil, you kill not only the weeds, rhizomes, roots, seeds, and 'bad' bugs and pathogens - but also the very things that make soil prolific and productive. Rot encourages healthy growth.

I hear you, but these weeds tend to not give up easy. As far as I know, there is not a good way to separate them from the unintended critter targets -- other than maybe screen sifting them? Maybe I should look at that, as well.

Full soil sterilization of an acre will require a lot of money and time, and still may not be as thoroughly done nor as beneficial as you think.

In real life I do various engineering problem solving type things (probably why this approach to this problem, huh? ), and part of what I do is to make otherwise expensive and difficult things cheaper and easier. Sometimes a good thing, sometimes not. So at any rate, this will have a constraint that the method selected and used be fairly cheap and easy, so that is not much a concern. Whether it works or is effective, is another subject.

Depending on your soil structure - and it varies from area to area, even in an acre! - sandy, loamy, clayey, surface vs subsurface, what it has in it as well as what it does not, what kind of water it receives/holds, what sort of temperatures and even winds it is subject to - these are all considerations. Before you do a single thing, take several test samples from several parts of the acre, and take them to your extension agent to have them tested - and ask what is done in your area for weed control, pest control, etc. They may be able to point you in a much cheaper and much more beneficial direction.

Yes, the locals have their methods. This being Texas, we love Chemicals. Chemicals in our water, Chemicals in our air, Chemicals on the ground, and of course, Chemicals in us. So did I mention the local solution? Chemicals.

Downside on that is an issue of getting an Organic Listing, as I mentioned to FOAD, above.

Thanks.

[Philip T]

Originally Posted by azoria

I remember watching this large scale soil sterilization on farm acreage in California years ago when a lot of cropland was being converted to vineyards. Apparently grape vines are susceptible to a host of soil born pathogens.

They covered the land with black plastic and let the plastic sit there all summer, superheating the ground for months. It was a strange thing to see, entire river valleys covered in black plastic.

You could try this? Cover your acre with black plastic and leave it there for the summer.

We were hoping to bring the site up for a Test Run this Spring -- for the first acre or so, but that may be good idea to prep additional areas for expansion for a Fall Planting, or next Spring. Thanks.

[FOAD]

Under those circumstances, where water is free, and you have a solar boiler, I would just hammer the place with several applications of water, then cover it with plastic and let it sit for a season.

I only worry about the microbes dying off, when I'm dealing with potting soil. This is because a sterilized container is a dead zone and no microbes can find their way into that environment. Whereas an open field will have microbes in it in no time flat.

I don't believe anyone ever WANTS to set out to sterilize soil, but sometimes it is a necessary evil. It sure will be hard work, so if you are going to do it, I say boil some water and do it right.

Again... Good luck!