Composting 101

If we ask an experienced gardener what comes to mind when he/she hears the phrase “black gold”, he/she will probably not answer the oil, but the compost. Compost is a biological substance that results from composting and transforms the soil of our garden. It gives extra nutrients and flavor to the fruits and vegetables that we harvest from our garden.

Composting is a highly environmentally friendly practice with excellent results in terms of plant nutrition, offering significant money savings.

In composting, organic wastes (from our kitchen or garden), such as leaves, grass, twigs, peels, and other food residues (eg eggshells), are converted through various processes and with the help of soil microorganisms in a nutrient-rich substance called compost.

Using it properly and adding it to the ground, we can moderate soil erosion, enrich our field/garden with nutrients, and increase its ability to retain water.  At the same time, we significantly reduce the amount of our household waste, as part of them is recycled.

Here is a tip before we start

The most important advice we can give to someone interested in starting composting is: Do not over-analyze things. You do not need to constantly move around with a thermometer measuring the temperature of your pile or carefully weighing the individual materials to reach the perfect ratio of carbon to nitrogen.

Composting has been ongoing for millions of years, even without the perfect temperature, humidity, and material ratio.

What we will need: The essential materials for Composting

We divide the primary materials for composting into green (fresh) and brown (dry).

By green, we mean most of our kitchen waste. We can use peels of fruits (e.g., apples, bananas, oranges, kiwis), salad leftovers (lettuce, cabbage, etc.), and whole fruits and vegetables ready to rot.

The category of fresh (green) materials also includes all the waste of our garden (flowers that have begun to wither, cut green grasses, fallen leaves, etc.). The high percentage of nitrogen these materials mainly contain makes them indispensable for composting.

Respectively, in dry materials, we include garden soil, existing compost, straw, sawdust, hay, chopped dry branches, grass, and leaves, etc. These materials are rich in carbon.

Finally, we can use eggshells (rich in calcium), leftovers from coffee filters, shredded newspapers and cardboard. The greater the variety of raw materials we use for composting, the higher the quality and nutritional value of the compost that will be created a few weeks later.

What not to use for composting

Not all kitchen and garden materials are suitable for composting. Using leftovers from dairy products and meat is forbidden, including cured meat products. Of course, we cannot use anything plastic or synthetic. Also, a beginner should avoid using manure, as it demands experience in selecting the beneficial-suitable kind.

Size and Proportions of materials

As a general principle, we would say that these two groups of materials should be in equal proportions, about 1 dry to 1 green. These ratios refer to shredded rather than whole materials. However, you should not worry if you do not achieve the perfect balance, as composting will start anyway. On the contrary, it is essential to chop in very small pieces, all materials (from both categories) in appropriate sizes, before placing them in layers in the digest silo. This step is necessary to facilitate air circulation between these materials and empower aerobic bacteria to decompose them as quickly as possible. If we leave them intact (e.g., if we use a whole banana peel or a whole tomato), without passing them through a shredder, the composting process will be quite delayed, and it may take an entire year instead of 2.5 months.

After ensuring that our materials are in the right size, we will place them in the digestion silo. An appropriate compost bin should be lightproof and provide the best possible temperature and humidity conditions, as the microbial activity and the temperature should spiral over time. At this point, we need to mention that it is possible to construct a homemade compost bin with pallets, but it will certainly not have the quality and convenience of a well-made, store-bought composter.

After we have placed the digester in a shady spot of our garden, we will put the materials of the green and brown group in layers (one layer of green materials and one layer of dry materials). We need to place dry materials, like soil and compost, at the base and the top of the pile. The stratification (layering) process is quite important, as it will accelerate the microbial activity, and we will not have to mix the silo very often.

Moisture: The key element for successful composting.

Ensuring adequate humidity in our silo is one of the most critical factors for composting. Once we have made a pile with a length, width, and height of at least 70 cm (2.3 feet) and 4-5 layers, we must wet our pile before closing the compost bin. Then at least once a week, we should add some water (empirically) to the top of the pile to maintain the humidity at desirable levels.

Duration of Composting process and integration of new materials to an existing pile.

If you follow all the steps mentioned above, the compost may have already started forming by the 10th-12th week. If you use finely chopped materials, the composting will be completed in up to 6 months (26 weeks). During all these weeks, besides providing moisture, you can sparsely stir the pile, checking that the temperature has risen in its center and there is indeed microbial activity. Adding new materials to a pile where composting has already begun should be done prudently. In any case, the new materials added should not exceed 20% of the total amount.

We can integrate fresh organic wastes by opening a hole in the top of the pile. After adding new greens, we can close the hole by adding dry material to the top.

Composting is completed when our mixture has acquired a dark brown color has a strong soil odor. At this stage, the temperature inside the pile is the same as the ambient temperature (we observe no vapors when digging towards the center of our pile). Many gardeners leave the compost for at least 2-3 weeks before using it in their soil.