Trench Composting – soil incorporation – an overview
Trench composting (sometimes called pit composting) is just what it says. You dig a trench, or a pit, add a layer of your raw materials, cover them with soil and let it lie. Your hole or trench should be about a foot deep and you fill it in once you have added about 4 inches of compostable materials. This is one of the simplest ways to deal with kitchen waste and depending on the temperature, the waste you are burying and the micro-organism population in residence, you will achieve compost in between one month to a year. This is a method of Cold Composting.
You can bury your waste in any area – some gardeners dig their trench around the drip line of their trees, providing each tree with its individual shot of goodness. If you dig pits in your garden beds, however, in one or two years you will be able to plant over that area and your tomatoes, or potatoes, or whatever, will have a wonderful bed in which to grow. If composting is not fully complete, the new roots will help to finish the job as they develop.
One variation of trench composting – sometimes known as the Vertical Composting, or the English System – is rather more complicated and time-consuming. It can be used over large areas or adapted for a smaller plot and a full cycle of this system takes 3 years to complete. In order to really work this to its best advantage, you need to set up your area into three rows each about a foot wide and as long as you want.
As with random pits or trenches, you should dig about one foot deep and fill when your layer of compostable materials reaches about 4 inches deep. It is really important that these guide-lines are followed, as if your waste is situated in too shallow a trench, you run the risk of animals catching the scent and trying to root everything up.. Yuk! Some sources suggest that to lessen the risk of this happening, you should add a little soil every time you add new materials. Animals apparently do not like their food to have soil on it. In all honesty, any dogs we had at home were quite happy to unearth an old bone and to chomp on it regardless of what was on it! I can’t see rats being any more or less particular. May be worth a try, though.
Just one word of caution. Be careful if adding a large amount of fallen leaves or other high carbon-content materials to your trench, particularly if you are working close to plant roots. Material such as this requires a lot of nitrogen to aid in decomposition. You run the risk of depleting the nitrogen needed by your plants for healthy growth if you do not take steps to re-balance the situation. You can do this by adding a small amount of blood and bone to your trench. Better though, to avoid the problem in the first place. Incidentally, it is for this reason that it is recommended that you let your trench lie fallow for twelve months after you fill it in, in order to be sure that composting is complete and the nitrogen in the soil will be available to your new plants.