Composting. For your garden, your trees and for the climate

With your own compost you can make a small but valuable contribution to protecting the environment. With the leftovers from your kitchen and materials from the garden you create a living ecosystem, store carbon dioxide and improve the soil. And you can make your own fertilizer, your black gold, which you can later use for your trees and other plants. 

Sounds really good, doesn't it?

Let’s take a closer look:

What is composting anyway?

Composting is a core part of every organic garden. Composting is the breakdown of plant and mineral materials and the creation of nutrient-rich humus. The resulting compost provides valuable food for plants, which can break it down as needed.

What happens if you don’t compost?

If you don't compost, valuable organic material will either be burned or composted somewhere else, missing out on the opportunity to make a small contribution locally and improve the local ecosystem.

If your waste ends up in a landfill, it usually decomposes under anaerobic conditions, i.e. without the presence of oxygen. This process leads to the release of methane, a greenhouse gas that is many times more harmful to the climate than CO2. This is important because methane contributes significantly to global warming. It is estimated that around 20% of global methane emissions come from landfills.

Composting, on the other hand, is a natural way of recycling waste that involves breaking down organic materials under aerobic conditions. This process produces CO2 instead of methane, and the end product – compost – is a valuable humus that improves soil quality, increases water retention and promotes plant growth.

And just as importantly, composting closes the nutrient cycle and reduces the need for chemical fertilizers, the production and use of which can also be harmful to the climate. In addition, compost binds carbon in the soil and thus helps to reduce atmospheric CO2 concentrations.

The ideal location for your compost

A place in partial shade that is sheltered from the wind is ideal for your compost site. Your compost needs to be in contact with the soil so that the soil organisms have direct access. It should be protected from too much rainfall and too much sun and heat.

Which materials can you compost?

Basically, you can compost all plant-based materials, such as fruit and vegetable scraps, coffee grounds, tea bags and garden waste such as leaves, grass and small twigs. You can also compost eggshells. However, you should avoid meat, dairy products and oily food scraps as they can attract pests and are harder to compost. Also make sure that no plastic ends up in your compost.

How do you go about composting?

• Make sure your compost heap is in contact with the soil. This allows the exchange and regulation of moisture, living organisms and nutrients with the soil.
• Add mature compost to your compost to help it get started. Do you have access to mature compost? Perhaps your neighbor has a spade full to spare? Alternatively, you can use a commercially available compost starter.
• Make sure you have the right ratio of "green" (nitrogen-rich materials like kitchen scraps and freshly cut grass) to "brown" (carbon-rich materials like leaves, straw, and wood chips). A good ratio is about 2:1, so twice as much "brown" as "green."
• If you are composting garden material, we recommend that you chop the material up before composting. This is especially worthwhile for woody waste such as branches and twigs.
• Make sure there is enough air supply. The compost needs oxygen to prevent it from rotting. One way to do this is to turn the compost occasionally. We recommend turning and loosening the compost once or twice a year. WOther possibilities are Mix in coarser material and make sure your compost bin has sufficient ventilation openings.
• Check the moisture: The compost should be moist but not wet. A compost that is too dry slows down the decomposition process, while a pile that is too wet will start to rot. If it doesn't rain for a long time, you can moisten the compost with rainwater. If it rains heavily, you can cover it with compost protection fleece, straw or reed mats.
• Be patient: Composting is a natural process that takes time. Depending on conditions, it can take several months to a year for the compost to mature and be ready to use.

Some more background: What processes are involved in composting?

When animals or plants die, their biological mass is broken down by small organisms and microbes and converted into stable humus substances. The decomposition process that occurs can take place in two ways:

• Through rotting: This process takes place in the absence of oxygen (anaerobic). The microbes active in this process do not require oxygen. In addition to foul-smelling gases such as hydrogen sulphide, butyric acid and ammonia, phenolic compounds are produced. These are toxic and harmful to many plants.
• By rotting: This process takes place with the aid of air-breathing microbes. This process is only successful if the material to be composted is in a suitable condition and is composed in a certain way. The C/N ratio, moisture and aeration must be balanced.

Tip: Do a smell test occasionally, because a bad smell is a clear indication of rotting processes.

For further information we recommend the free Composting Guide of the Federal Environment Agency.  

Worm compost: Composting with earthworms

A special form of composting is the production of Worm compostCompost worms transform organic kitchen waste into nutrient-rich humus. The end product contains valuable plant nutrients, humic acids, and a variety of microorganisms that promote soil life.

Worm compost can be produced even in small spaces, making it suitable for many households. The finished worm humus can be used directly to improve the soil. Additionally, a product called worm tea or worm compost extract is produced, which can be used as a liquid fertilizer.

Worm compost is particularly suitable for the care of trees, as it not only provides nutrients but also improves the soil structure and strengthens soil life.

Bokashi as fermented compost

Besides the classic compost, there are also Bokashi Another way to make good use of kitchen waste. Organic materials are fermented by microorganisms in the absence of air, instead of being decomposed by oxygen.

Bokashi requires little space and is therefore also suitable for balconies or terraces. After a further maturation period, the fermented material can be worked into the soil, where it promotes soil life and provides valuable nutrients.

Composting and bokashi are not mutually exclusive. Many gardeners use both methods to process organic waste and keep their soil fertile in the long term.

Fertilize your trees with compost

If you have now produced your own compost and would like to know how you can use it to fertilize your trees, we recommend the following article: How to fertilize trees correctly?