Reduce Landfill Blog Posts

Burying your Kitchen Scraps/Trench Composting

How to bury your Organic Waste

Posted by Angus Stewart

Aug 20

Burying your kitchen scraps, or ‘Trench Composting

This is arguably the simplest and most effective method of composting high nutrient material such as kitchen scraps. The basic concept is to simply dig a hole, around 30cm - 40cm deep, this is most effective if done into the topsoil layer to suitable depth, as this is the soil layer where most earthworms feed, live and reproduce.  What happens during this process is that the natural earthworm population present in most soils will expand to utilise the extra food source that has been created in the soil. As well as earthworms there will also be fungi and bacteria present in the soil as well that live on organic matter, so it is the same process that happens in a compost heap in that these organisms will breed up to utilise the organic material.

The benefits to the soil are enormous, there are direct advantages from the earthworms digesting the organic matter and releasing the nutrients from that in an available form to plants for growth. The earthworms will also be moving in and out of the surrounding soil and tunnelling as they do this they aerate the soil, creating little channels through which water, air and plant roots can move freely, greatly aiding plant growth.

Many of the micro-organisms which are found in the digestive tract of earthworms are actually beneficial to plant growth and are excreted dispersed throughout the soil along with the nutrients and humus that the worms create. These beneficial micro-organisms act in several ways to benefit plants; they can antagonise pathogenic organisms by competing with them and reducing their populations in soil. Some organisms naturally produce antibiotic substances which can kill pathogenic organisms such as bacterial soft rots.

In conclusion, the process of burying kitchen scraps to form an in-ground compost heap in topsoil is a very efficient way of composting.  
The best way to practice this method of composting is to keep practice a rotation system operating in the home vegetable garden.  This means keeping one bed free of plantings each season to use as a composting site and allow the soil to be replenished. The time required for this composting process (in particular for high nutrient materials like banana peels and potato skins) is between one and two months. This allows sufficient time for this matter to be broken down into the soil by the earthworms, fungi and microbes. The earthworm castings are key to creating an ideal soil environment for plant growth by renewing the nutrients in the soil and rebuilding the structure of the soil.

There are sometimes issues with seeds and things like potato peels actually sprouting new plants in your compost. These ‘volunteer plants’ are fairly easy to deal with, there are a couple of options there, the first is to simply dig these back into the compost where they will break down, plants like tomato and pumpkin seedlings, watermelon, rockmelon, potatoes and sprouts can all be dug back into the compost at least a week before planting. This will act as a green manure in the soil adding nutrients and humus as it breaks down further.  The other option is to let those plants grow if they have coincided sprouted during the appropriate growing season, things like cherry tomatoes can form productive healthy plants from these volunteers if replanted. Burying your kitchen scraps is a very effective method of composting, provided you have sufficient space to implement a seasonal rotation system in your garden.


Avoid composting or replanting plant material that is obviously diseased or carrying mould or fungal infections as some organisms can survive the composting process and spread disease.

There are a few leaf borne viruses and infections that are the exception to this rule and can be safely buried in this type of composting system. These include foliar problems like black rot and fruit with brown rot, and most powdery mildews and rusts as these cannot survive for long once the leaves have fully biodegraded in a healthy compost heap.


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