Soil Occultation as Organic Weed Control in a No-till Garden

Do you have a large garden area that you don't want to weed by hand? What if you could get rid of the majority of your weeds organically before you even planted your garden for the season? Soil occultation as organic weed control could be your answer.

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The New Garden First Steps

Last year, I decided to expand my garden space. I use organic, no-till methods whenever possible. It is so important to try to maintain soil structure and health. That is why I wanted to try soil occultation as organic weed control with this new garden space. I never use chemicals on my gardens.

We live in a very wooded area, so we had some land cleared. I also had some top soil brought in because our soil is clay and rocks in this area of the property.

I planted a cover crop in the fall. The cover crop had a mix of a bunch of different plants. This spring a lot of crimson clover came up from the cover crop.

About a month ago, I had some composted manure brought in. My goal is to be able to produce enough of my own compost for all of my gardens at some point, but until then, I have someone who I trust with some really good composted manure.

Note: One thing you want to make sure of is that you are not putting “hot” manure on your garden. If you have chickens or other animals, you can save their manure and let it sit for a few months to a year to allow it to compost. It will then be safe to use in your garden and yard.

Soil Occultation at Work

After putting down the composted manure, I spread a 5 mil silage tarp over the garden and put rocks, tires and dirt on top to hold it down. One side of the tarp is black and the other side is white.

This process is called occultation. Basically what happens is I put the tarp on with the black side up. The soil underneath heats up and weeds germinate underneath. With no light or air movement, the weeds die under the tarp.

Depending on the time of the year will determine how long the tarp needs to stay on. In colder months, it will take longer for the weeds to germinate. In the heat of the summer, it will take a lot less time. I put this tarp down at the end of march and it’s been a little over a month.

I’ve been checking it along the way, and there were a lot of weeds that came up. Once the weeds die, they will add organic matter back into the soil.

What about Soil Solarization?

This process is similar to soil solarization. The only difference is that with solarization, clear plastic is used, but it’s the same idea of heating up the soil to germinate the weed seeds and then kill them off.

From what I've read about occultation and solarization, they seem to have the same outcomes. Some studies show solarization works better long term, but there's not a lot of data out there.

Concerns

One concern I have with occultation and solarization is the possibility of destroying some of the soil structure. I don’t know how much of a problem that will be, but I feel more comfortable using this process than using chemicals on the garden.

I have heard really good things about using occultation to help with weeds. Since this is the first time I have tried this method, I will have to post an update to let you know how it went. I'm excited to see if this will work as a good organic solution to weed control for such a large area.