Sheet Mulching is a process used to build soil, add fertility and/or limit erosion. It can also be thought of as an aggressive form of “composting in place”.
I have a part in my front yard that is subject to water saturation and erosion during rain events. This is because I have an eve on my roof that drains directly at this area. It is enclosed on all sides by a concrete driveway as well as a sidewalk. The area was full of fill dirt that was placed there after the house was built. I would like to deal with my erosion problem and the fact that it was full of local grasses and weeds. Eventually I will plant of couple of fruit bearing trees a sort of mini food forest, but for now I am going to plant it with sweet potatoes. Its a little late in the year to plant sweet potatoes, but I am hoping to get at least a 100 days before the frost hits and get some form of a yield.
The process of sheet mulching and the layers in it make a lot of sense once you see it. I actually suggested this process to one of my vendors at work that had issues with his septic leach field retaining too much moisture. There are several layers that can absorb moisture as well as retain it. This is the process:
Step 1): Clear the area of as much vegetation as you can without exerting too much energy. You will see why in step 2. In this step you will need to aerate the soil. You can do this with a pitch fork by stabbing the ground and moving the fork in a circular fashion. For larger scale projects you may need an aerator that attaches to the rear of a tractor. Water profusely.
Step 2): Lay down a layer of veggie scraps or if there was overgrowth that you removed in step 1 you can substitute that. You could simply leave the existing vegetation in place or lay it over by stepping on it. I had sparse growth so I extracted it and spread it out as much as I could since I didn’t have veggie scraps. Water again.
Step 3): Lay down a layer of cardboard up to 6 inches thick. You can layer the cardboard against the flow of water to limit erosion or layer it with the flow of water if you want to encourage speeding it up. Water again.
Step 4): Lay down of at least 3 inches of compost, preferably 6 to 8 inches. Water again.
Step 5): Lay down a layer of shredded woody mulch or preferably straw. Water again.
Step 6): Lay down another layer of 3 inches of compost. You can do a little more, but it’s not necessary.
Step 7): Top off with a layer of straw.
That’s pretty much it. In the area of my property I skipped step 6 and 7 due to the fact that it would exceed the height of the area. Remember there are no hard rules in Permaculture. Take this as a guide. If you didn’t have access to compost, you could use fill dirt. If you didn’t have access to straw or woody mulch, you could use tree leaves. This is set up will eventually turn into dirt as it composts itself.
My project before starting.
Step 1: Remove vegetation and aerate.
Step 2: Layer of green vegetation. I didn’t have veggie scraps
Step 3: Layer of cardboard. It may be hard to see, but I arranged the cardboard in layers to limit erosion.
Step 4: Layer of compost. I bought 4 x 40lb. bags of cow manure/compost and it still wasn’t enough to do this area. I had to use my entire onsite compost pile.
Step 5: Layer of straw or hay in this case. It was all that was available at this time from the local hardware store. The area to the left will be next after this. I planted sweet potatoes last night and the whole area looked great.
This was a great workout as well. Enjoy implementing this process where you feel it will benefit you.