If you haven't heard of trench composting (AKA in-situ composting) and you're the sort of person who likes to maximize efficiency, while minimizing hard labor, then composting directly in your garden bed is something I think will excite you. The results are fantastic for minimal effort.
If you're a lazy gardener like me, the whole idea of slaving away creating a compost pile causes a cold shudder to run through your body. Fear rises slowly as the idea of toiling with a garden spade or pitchfork, sweating, having to turn the pile multiple times over months until that black gold is ready to dig into your vegetable garden. More digging.......NO!!!!
Table Of Contents
What Is Trench Composting?
The direct trench composting method is a way in which you can compost kitchen scraps, leaves, even weeds, directly into trenches or holes in the ground where you will eventually plant your seedlings right on the top.
You're burying the scraps and composting materials exactly where you are going to grow your plants in the coming season.
What's really nice about the pit or trench composting method is that it's organic, invisible, no pile of rotting compost in the corner of the garden, no smells or nasty whiffs, and you can do it anywhere in your garden, not just in vegetable beds.
This composting method is an anaerobic one, meaning that the process of breaking down the scraps and garden waste happens without the presence of oxygen, unlike on a conventional compost pile
Before we go on, here's a great video that explains the methods with some useful tips, including just laying scraps on the surface and covering with soil, and actually digging a trench or hole to bury them in.
How To Do Composting In Pits Or Trenches
The pit or trench compost method is remarkably simple.
Step 1. Take a spade or garden fork and dig a trench between 45-60 cm (18 - 24 inches) deep. I like to keep my trenches to around a spade or forks width, but a little wider is fine too.
Step 2. Add vegetable scraps, grass clippings, leaves, weeds, and any other small prunings you may have at hand. Lay them out at an even thickness in the bottom of your trench.
Step 3. Cover with the soil you just dug out of the trench.
Step 4. Er....sorry...that's it! There is no next step....unless
If you dig a deep trench, it's fine to throw the available scraps into the bottom, cover with a few inches of soil, and then repeat each day until the trench is full. Always ensure the craps are well covered to prevent rats and other vermin digging up your scraps. Many people are worried about issues surrounding trench composting and rats, but I have never had a problem. As long as you cover the scraps well, and never try trench composting meat or cooked food, you should be fine.
If you don't want, or need a trench, the posthole composting method is a great choice too. Everything is the same regarding digging depth etc, but you just dig a home, dump your scraps in the bottom, and cover. Ideal if you have plans to plant fruit trees or berry bushes next season.
Benefits Of Composting Directly In A Trench?
There are a ton of great reasons to bury your kitchen and garden waste directly into a trench. I've touched on some of them in the previous sections. Less work, less huffing and puffing, a quicker result, no need to dig compost, manure or fertilizer into the soil before planting.
Let's consider a few more distinct benefits:
- Compost even if your local rules prohibit it. This seems like an odd one, but it's true. Some modern developments and town rules actually forbid composting. Why that is, I have no idea, other than the mistaken concept that it attracts vermin and odors. Covering your composting materials directly in a pit or trench overcomes these silly rules. Sweet!
- An odorless and invisible solution to household waste. As I mention frequently on this site, closing the circuit on waste entering and exiting your property is an environmentally wise thing to do. We all have some products coming into our homes from outside. Food, paper, cardboard, plastics etc. Of course, you can't just bury all the junk in your backyard, but composting as much as you can is a great way to improve your soil AND to reduce your ecological footprint.
- Rich nutrition to plants, exactly where they need it. When a plant starts to grow, it's roots head deeper and deeper into the soil, in search of nutrition. A layer of compost 45-60cm below the surface provides a concentrated source of nutrition exactly where the plant can make best use of it. The deepest compost layer will encourage the roots to be stronger and drive deeper in search of nutrients. The compost improves both the drainage AND water retention properties of the soil, creating an environment where the plant can better cope with dry conditions.
- No investment in containers, or big DIY jobs building compost bins or tumblers. It's a free method which is quick and easy, which is always an encouragement to actually do it.
- Works great in raised beds. I have two long raised beds in my garden, and I fill the trenches with scraps every fall. I often rotate the composted bed with a planted bed during the spring and summer, leaving one for composting and the other for growing. Come the autumn, I can plant some winter vegetables into the composted one and then trench out the other. Like a rotation system I guess.
Potential Disadvantages And Limitations?
There are no major disadvantages with the trenching method of 'dig and drop composting'. But there are a couple of potential limitations or problems that can occur, some of which are easily addressed.
- The rate of decomposition is relatively slow. A hot composting method or Bokashi composting are methods where the scraps break down pretty quickly. Composting in a trench is a much slower, 'cold' composting method, it takes quite some time for the composting process to be complete. But, if you 'plant' your scraps in the fall, by the Spring it will be ready. It just takes a little planning, but the benefits of ease and quickness to implement outweigh the relatively slow process.
- Vermin could be an issue for some, but ensuring that the scraps and waste are well covered should mitigate the chance of pests excavating your trench. If you have any concerns, laying a wide board over the filled trench until the soil settles is a good idea.
- The cold composting method may not kill weed seeds or plant pathogens. Adding weeds to the trench is fine most of the time, but it's important to not be covering weed seeds that are likely to germinate and give you problems.
With a few minor precautions, direct composting is an excellent use of your time and scraps. And of course, all the above disadvantages can occur in a standard compost pile, so a trench or posthole composting method isn't any more risky.
What Can I Put In My Trench?
Vegetable scraps and offcuts (raw, not cooked), fruit, leaves, grass cuttings, small clippings from the garden are all great for awesome trench composting results. Avoid cooked foods, bread, meat etc, as these will attract vermin. Trench composting leaves that have fallen from the trees in the fall is also incredible. I did this last year and was gob-smacked by the number of worms that have come to live in my food garden.
We're basically looking for green and brown nitrogen and carbon rich materials, but the ratio is far less important than say, the hot composting method where it's essential to get the right combinations.
How about pet waste?
Pet waste can be buried in a trench or hole, but you must not plant vegetables and other food crops above it. Although the risk of pathogens and bacterial diseases is low, it's best not to take chances. If you really must bury the stuff, plant ornamental trees or other non-foods above the trench or hole.
When Is The Best Time To Fill A Compost Trench?
Early fall (autumn) is a great time to dig your trench and fill it with scraps, allowing them to compost down over the winter. It takes a few months for the bacteria, fungi, worms, insects and other microfauna to devour their way through the raw scraps and cuttings, but by Spring, you'll have a vegetable or garden bed that is nutrient rich, with improved soil to plant directly into.
What Plants Could I Plant In Dig And Drop Composting Trench?
Almost any plant can be grown about a compost trench, but it's especially good for really hungry vegetables. Using a compost trench for runner beans, zucchini, pumpkins and squash ensures a monster crop when harvesting time comes around. There are certain vegetables like carrots that grow much better without a ready source of nutrients, but don't get too hung up in the technicalities.
To Sum Up
Direct composting is the simplest, quickest, most effective way to get nutrients into the soil exactly where they will be needed. It's kind of amazing how this method is not always the first thought for gardeners, when it's so simple. The results from trenching are always good, just keep in mind the potential issues and you'll be producing incredible crops next season.
That's it homesteaders and food growers. I hope this has been useful? Leave a comment and tell me how you do your home composting.
Oregon State Extension: No Turn Cold Composting
Mother Earth News: Burying Kitchen Scraps In The Garden
Rodale's Organic Life: How To Use Food Scraps In The Garden Without A Compost Bin
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