Vetiver/Compost Trenches 2.0

This is an update on my previous report about vetiver/compost trenches. Our first attempt at making these trenches was a big success. Surprisingly so, because the compost in the trenches kept going down, down, down to where it looked like very little was left after 6 months. This was a little discouraging at the time because I used five pickup loads of manure and rice hulls, plus I was watering it fairly often. The surprising part was how much compost I got at the end of summer.

Our fruit trees get lots of compost and green manure. However, the open areas between trees don’t get pampered nearly as much. The compost trenches provided plenty of compost after all, enough for a heavy compost layer between trees. Another key advantage was 99% success rate at smothering weeds along the edges of the garden beds. This is where pernicious Bermuda grass in the paths sends runners toward the fertile garden beds and creates the most weeding work.

One mistake though was covering the manure with rice hulls instead of straw (straw wasn’t available at the time). The hulls gradually washed down into the manure and the exposed areas on the surface dried out quickly and required extra watering.

Here are my ideas for improving the process next time – compost trenches 2.0. First, hoe the trenches to removes grass and weeds that grow during the rainy season. Then cover the trench with a good layer of rice hulls. Then add manure, sugar cane compost or other fungal inoculated soil mix if available, and more rice hulls. Cover everything with a thick layer of straw and water thoroughly. The main idea is to use the same materials as when making compost. (Your materials may vary slightly, but you get the idea.) In our case, we know these low cost agricultural by-products produce good compost, so it makes sense to use the same process in the compost trenches.

Next time around using this improved 2.0 version there should be virtually no weeds or Bermuda grass runners, and much less watering. Plus, I’m expecting to get higher quality compost.

Note how our available area to make compost is limited, so utilizing compost trenches is beneficial for us. And, the compost in the trenches is exactly where we need it – right next to the garden beds.

9 thoughts on “Vetiver/Compost Trenches 2.0”

  1. We compost big time on our farm in Costa Rica.

    All of our compost material comes from our farm. When you bring in manure and sugar cane material you also bring in their problems, their poison, and chemicals. As an organic farm this does not work. Our piles are maybe 4 to 5 ‘ high and 12 to 15’ long. We layer in manure and lots of fresh cut green grass clippings, veterier, weeds, chopped banana trees, the compost buckets and humanure buckets. The green grass clippings are key, they produce high heat and cook the pile. The piles are covered in weighted down black plastic to keep them moisture controlled and hold the heat in. We turn the piles over for the next 6 to 8 weeks using the backhoe and continue to cover them again. EM can be sprayed on the piles through out this process.

    • Yes, ideally you can get all materials from your own land. But our homestead is only 1/2 an acre or so. The materials we source are as organic as we can get — ex: a small farmer who herds 6 cows on fields near his home.

      Be careful with plastic on top of compost piles because it can turn anaerobic and breed harmful microorganisms. Most people make aerobic compost that needs lots of air. (Although we made anaerobic compost for two years, let it age and it turned out fine.)

  2. wood chips are a good top dressing, too.

    We have thick native grass here and I cut that like straw, and it works wonders for maintaining soil moisture. I also lay branches on top of the straw to keep it in place, because we get high winds, here.

    I bet your soil is amazing!

    • Unfortunately wood chips are not available here. Tree trimmers either leave everything in place or haul it to the dump. But I haven’t given up looking. I need wood chips or at least bamboo chips for the final forest garden mulch.

      Our soil is getting much better after 3 years of dumping 50-60 dump truck loads of soil amendments on the beds. There’s 6″ of black topsoil now with worms and mushrooms everywhere. All beds are covered with a thick layer of straw. What we’re still missing though is the final understory planting under the fruit trees. As you know, the plants themselves and all the soil microorganisms they attract are what really build the soil. The rains are starting so this step may have to wait until after the rainy season (other than throwing in a bunch of beans again).

      Here’s what the garden looked like a year ago:
      It’s WAY better now.

  3. Owen- please be advised that straw will wash down as well (it washed off the hill side of my swales) and even though I like it for mulch on the flatter areas because it’s cheap and available, it does tend to sprout a lot of wheat grass because of the residual grain in the bales. I’m thinking of maybe pinning down the straw with sticks the next time I mulch the swale hills, figuring that the sticks will eventually compost themselves.

    • It will be fine in our case because the straw is nearly flat. See the drawing and photo in the link above. And the straw and other compost ingredients are only in the trench during the dry season when there’s virtually no rain for 6 months. The rice straw we get has virtually no rice in it. But good points. These are the sort of things gardeners need to think about. Everyone’s garden is different and so gardeners have to figure out what’s best for them.

  4. Summary: Reduced hoeing of weeds offset the time spent watering. The manure from a local farmer and hulls from the rice mill are super cheap — maybe $30 total. So yeah, this was a good success and I plan on doing it next year.


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