While plenty of gardeners have dabbled with composting to some extent, achieving that sought after “black gold”—rich, nutrient-dense soil—is every gardener’s holy grail. But not everyone with a green thumb knows that there are a variety of ways to compost. If you don’t like having a constant pile of compost “cooking” in your backyard, trench composting may be just what you’re looking for.
Trench Composting: The “Lazy Man’s” Method
Trench composting is known as the “lazy man’s” method of composting because you’re burying your kitchen scraps directly into the soil, right in the garden. This hassle-free method is an easy way to enrich your soil without the odors, turning and watering, and the unsightly view of a large compost bucket or pile in your backyard.
While this method may be new to you, trench composting is far from a new method. In fact, it has been used to enrich soil by almost every civilization for thousands of years. In fact, when Native Americans buried fish under their mounds of corn, they were trench composting.
Why Choose Trench Composting?
Burying organic waste and waiting for it to decompose to add nutrients back to the soil creates an underground band of nutrients for your plants. It is one of the easiest ways to utilize your waste while returning organic material back to your soil. Your plants also get the nutrients they need without the hassle of aerating and sifting like you have to do with other compost methods.
Best of all, your pile of disintegrating kitchen scraps is out of sight and can fit just about anywhere you have diggable dirt. There are no wafting odors emanating from your decaying matter and, if buried correctly, it won’t attract vermin like other compost techniques sometimes can.
Trench Composting Methods
The term “trench” is used loosely, as it is basically digging a hole, filling it with kitchen scraps and garden waste, then filling it back up with soil. There are multiple ways you can effectively use this type of composting. The one you choose depends on what time of year it is and what type of gardens you have.
1. Dig and Drop Method
This is the simplest method of trench composting. It is a great way to compost large amounts of material at once, and an effective way of adding nutrients to your garden off-season. First, gather a week or two’s worth of scraps in a five-gallon bucket or composting pail. Dig a hole roughly 12 inches deep and wide enough to bury whatever scraps you have collected, dump in 4-6 inches of compostable material, and cover it back up with dirt.
Within a few months, the composting material will have broken down and enriched your soil with no extra work from you. Not sure what to do with your leaves in the fall? This method also works well. Simply bury them around your garden or flower beds. Mowing them up first will help them decompose quicker.
2. Trench Between Rows/Side Dress Method
These methods are effective during your growing season. It fertilizes and adds nutrients to existing plants. Simply dig holes or trenches a few inches out from the roots of your vegetable or flower plants and bury your everyday compostable material. As it breaks down, it will feed extra nutrients to the plants nearby as they grow. Used coffee grounds (filter and all) are an especially great side dressing for plants, providing extra nitrogen and improving soil structure. Crushed eggshells add a boost of calcium as they break down, great for preventing blossom end rot in tomatoes and peppers. If trenching between rows, be sure to plant rows far enough apart so that you don’t harm roots while digging.
3. Trench Rotation Method
This is another great way to incorporate organic matter into your garden’s soil while it’s growing. First, divide your garden into three zones: trench composting zone, pathway zone (where you’ll walk), and growing zone. Each year you rotate your zones, moving your trench zone to a different part of your garden, while also shifting your pathway and growing zones as well. After three years, you will have compost under every part of your garden. Just keep rotating and nourishing your soil.
Here’s What You Can Add To Your Trench
As with regular bin composting, trench composting is the perfect way to dispose of organic kitchen waste, including these items:
- Kitchen Scraps such as fruit and vegetable scraps, coffee grounds, and eggshells.
- Grass Clippings: Leave an open space in your garden to bury grass clippings this summer. Rotate your spot each year to help nourish your soil.
- Fall Leaves: Raked up and mowed leaves can also go in your trench compost. As with bin composting, leaves are considered “brown,” so it is helpful to balance them with some “green” so that all of the nitrogen in your soil isn’t taken up to help decompose the leaves. If you do add leaves in the fall, simply cover the leaves with other nitrogen rich items, such as grass clippings, vegetable waste, and coffee grounds.
- Surprise! Tea bags, cotton or wool rags, dryer lint, fireplace ash, hair, and animal fur—all can be added to your trench compost.
Here’s What You Can’t Add To Your Trench
As with any composting, with the exception of Bokashi composting, there are a few things you will want to avoid throwing in your trench compost.
- Animal Waste: In order to avoid the risk of pathogen spread, animal feces should not be planted within ten feet of any edible crops. It can be used, however, in trenches along ornamental gardens or in landscaped areas of your yard as long as it stays buried and can’t be dug up by young children.
- Diseased Plant Material: If you suspect any plant of having a disease, you will want to avoid tossing that in your compost. Unlike pile composting, trench composting produces very little heat and is not very effective at destroying pathogens. You don’t want to risk spreading the problem.
- Weeds with Seeds: If a weed has gone to seed, leave it out. After all, you don’t want to be putting weeds back into your garden (we spend enough time pulling them out)!
- Vegetable Seeds: While these seeds are friendly seeds, you don’t want vegetables to sprout where they aren’t intended. Try and avoid tossing veggie seeds in with your scraps, particularly tomato seeds.
- Wood: Sticks, branches, and wood chips, while organic, often take way too long to decompose, robbing your soil of nitrogen in the process. Also, avoid adding commercial-grade lumber to your pile, as it is usually chemically treated.
- Certain Paper: While newspaper and brown bags can enhance your soil, avoid magazine and catalog paper as these are often made with toxic materials.
- Used Cooking Oil and Fat: Fats and grease don’t easily breakdown and can also coat other materials, slowing decomposition.
- Meat and Dairy: The jury is still out as to whether you can bury meat and dairy in your trench compost piles. With the food buried directly into your garden, you won’t have to worry about unpleasant stenches coming from the quickly decaying products, however it is still possible to attract vermin and other unwanted pests from digging up your garden. While some gardeners use trenches to compost meat and dairy, if your gardens are near your house, it is probably best to err on the side of caution and leave them out.
- Inorganic Materials: For obvious reasons, you’ll want to avoid adding any inorganic materials to our trenches. Plastics, cleaning solutions, fertilizers, and pesticides can all transfer toxins to your soil and ultimately into whatever you grow.
Trench Composting Tips
- If you wish, you can line your trenches with newspaper to help retain water.
- The more shredded the material, the more quickly it will decompose.
- While you can trench compost all year, even during growing season, fall is a great time to amp up your digging. After you have harvested most of your plants, you will have plenty of room to dig large holes or trenches to fill with leaves, organic kitchen waste, and grass clippings. Fill your hole before the ground freezes, leaving all that nutritious waste to decompose over winter leaving you with better soil come spring!
The Downside of Trench Composting
Some common drawbacks of trench composting are that you have to dig holes and cover them with dirt every time you bury your kitchen waste, which isn’t for everyone. Those holes cannot be refilled until everything you have buried has decomposed or you will create a big mess digging it back up.
While trench composting is a great way to add nutrients to your soil in the off-season, once the ground freezes, digging holes can be tricky. Also, because there is little aeration in trench composting, items take longer to decompose than traditional compost piles. However, if you have the space and the time, trench composting is an inexpensive and easy way to create beautiful nutrient-rich soil for your plants.
Article by Natalie LaVolpe.