Distinction between compost and humus
Humus is the term used to describe the totality of all organic substances in the soil. Humus is formed naturally, without human intervention, by the decomposition and conversion of dead, organic material of animal and plant origin by soil organisms.
The build-up of a fertile humus layer takes place very slowly. In temperate regions of the United States, like the Midwest, it can take 100 to 300 years for just 0.4 inches of fertile topsoil to form. In other regions, this process can be much slower and take up to 1,000 years, depending on factors like climate, organic matter availability, and soil composition. This is why composting is so beneficial: composting produces nutrient-rich „compost humus“ after only a „short“ time (within six to twelve months).
The word compost has its origin in the Latin adjective „compositus“ and is translated as „to put together“ or „to compose“. While humus is created without human intervention, we need to be actively involved in the creation of compost. We must collect dead, organic material of animal and plant origin, pile this material up and actively influence the rotting process by turning it over, keeping it moist and covering it.
Compost is therefore a humus-rich decomposition product, which is made by the process of decomposition of decomposed, dead, organic materials in combination with physical and chemical processes and the activity of soil organisms under the influence of humans.
Advantages of composting
Composting organic waste has many benefits for us and our environment. „Compost humus“ provides your garden soil with essential nutrients, improves soil structure, increases soil stability and helps to improve the water and air supply in the soil. With healthy and fertile soil you can increase your crop yields. Your plants will be stronger, healthier and more resistant to pests.
Thanks to „compost humus“ you can do without synthetic fertilizers and the use of peat (peat soils), a raw material that only grows slowly and is in short supply. Peatlands are preserved as a habitat because of this.
The composting method gives you the opportunity to return dead organic material directly to the material cycle and actively contribute to the preservation of our environment. Because through the production of „compost humus“, resources are conserved and landfill waste is reduced as a result of waste minimization.
Organization of composting
Today, composting can take place in different ways.
- If the organic waste is composted in one’s own garden, it is called selfcomposting.
- Composting in the community, for example in allotments, housing estates, schools or kindergartens is called community composting.
- Composting in public facilities such as forestry and agricultural enterprises, city garden centers or green spaces is called decentralized composting.
- In centralized composting, organic materials are collected in large quantities and then composted. The material for this comes from organic waste bins, green waste facilities or is delivered directly.
Composting on your own
There are many advantages to composting your own waste:
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The composting site is close by and can be reached quickly on foot.
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No long transport routes are required.
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Composting in your own garden requires minimal financial and technical effort.
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You are not dependent on large, expensive equipment and can reduce or eliminate the need for store-bought fertilizers.
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By composting yourself, you have direct control over the quality of your compost.
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Self-composting allows you to recycle organic "waste" directly in your garden and return valuable nutrients to the soil.
Please Note
Before composting human waste, please check your local and state regulations to ensure compliance. Composting rules vary across different regions, and some areas have specific guidelines for processing and using composted materials.
Compost location and size
The ideal compost site is protected from the wind and shaded. You can easily reach it with a wheelbarrow via a paved path. To avoid odor nuisance, you should make sure that there is a sufficient distance between your house and the neighbouring property.
The size of the compost depends on the space you have available and the amount of organic waste you want to compost, as well as the composting method.
Please Note
If the compost is too small, it cannot heat up properly and decomposition is slow (see also
-> Composting methods). If the compost is too large, there is a risk that it will not be well aerated and will start to rot. As a guideline, you can use the following information: Compost volume: at least 35.3 cubic feet with a base area of approximately 3.3 feet (W) x 3.3 feet (D). So that the surface area is as small as possible in relation to the volume.
Compost systems
Compost can be placed in bins (compost silos, compost bins) or in a heap (compost heap).
Compost bins are space-saving and are well suited for small and medium-sized gardens. They are available in various designs and materials such as wood, metal or plastic. Bins made of materials such as metal and plastic are more robust and durable. With metal bins, however, there is a risk of heavy metals dissolving and being released into the compost. A wooden composter may look nicer and blend better into the landscape. If you choose a wooden composter, you should make sure that it is made of untreated wood that is difficult to rot (e.g. larch).
Nevertheless, it is unfortunately unavoidable that the wood will decompose over time and you will have to replace the composter with a new one. Quick composters or thermal composters are designed to speed up composting.
Compost container
When buying a composter, consider the following points:
- The composter should be open at the bottom, i.e. it should not have a base. This way it can stand directly on the ground and the soil organisms can easily migrate into the compost.
- To prevent the compost from molding, it must be ventilated. For this purpose, the side walls of the composter must have a sufficient number of openings in the form of holes, cracks or crevices.
- The composter can be filled easily if the side walls are not more than 3.28 feet high.
- To make it easy to remove the compost, it would be ideal if your composter had an opening at the front.
- Ideally, your composter should have a lid to prevent rainwater or flying weed seeds from getting into the composter. Composters without a lid can be covered with a compost fleece. To prevent the cover from landing on your neighbor’s house during a storm and possibly causing damage, you should attach the cover you use so that it is storm-proof.
What to compost
This can go into the compost
- Tree and hedge cuttings (shredded or chopped)
- Leaves (shredded)
- Grass cuttings (dried)
- Bark (shredded)
- Straw (shredded or chopped)
- Woody stems (shredded)
- Vegetable waste (raw)
- Fruit waste (raw)
- Fallen fruit
- Crop residues
- Withered flowers and plants (without pesticides)
- Potting soil (pest-free)
- Compost paper bags
- Coffee grounds and tea (in household quantities)
- Eggshells from boiled eggs (crushed)
- Wood ash (from untreated wood)
- Sawdust and wood shavings (from untreated wood)
- Wood wool (from untreated wood)
- Wool scraps (sheep’s wool only)
- Hair (untreated)
- Small animal dung and feces
This should not go into the compost
- Diseased plants
- Weeds and neophytes
- Hoover bags and contents
- Sludge from gutters
- Granulated litter
- Cigarette ash and butts
- Street sweepings
- Used handkerchiefs, paper towels and nappies
- Printed paper
- Treated wood
- Leather
- Rubber and natural rubber
- Textiles
- Varnishes and paints
- Oils
- Plastics and composites
- Hygiene articles and dressing materials
- Cleaning agents
- Metals
- Glass
- Construction waste
- Mortar
- Medicines
Tip
It is a good idea to keep a stockpile of leaves and wood chippings for the winter. This way you can spread wet material, such as kitchen waste, mixed with the dry material on the compost in winter. This prevents the compost from becoming too wet and starting to rot.
In order to avoid problems during composting, we recommend that some organic materials should only be added to the compost in accordance with the instructions below or, if necessary, should rather be disposed of in the organic waste bin or in the residual waste.
Leaves
The leaves of oaks, chestnuts, poplars, birches, plane trees, beeches, walnuts, spruces and acacias release tannic acid during decomposition. This can acidify the compost. Therefore, you should not put leaves from these trees on the compost in large quantities. Foliage from maple, lime, willow, alder, rowan, ash and hazelnut can be composted well.
Bananas, citrus fruits, bought flowers and plants
Peels of bananas and citrus fruits may contain pesticides and fungicides. Often bought flowers and plants are also treated with pesticides. If you are unsure about this, it is better to dispose of these organic materials in the residual waste.
Feces
Small animal dung and litter from hamsters, rabbits or birds, feces from carnivorous animals and human feces should only be composted if you can ensure that pathogens of concern have been rendered harmless during composting.
Food waste
Cooked food leftovers, meat, sausage, fish, cooking oils, bones, pasta, shells of raw eggs are rather unsuitable for the compost. They can attract rats and mice. Cats and birds can scatter the food in the garden. There is also a risk of salmonella spreading through the food scraps. Salmonella could be spread by flies, for example. Therefore, food leftovers belong in the organic waste bin.
Diseased plants, weeds and neophytes
Diseased and pest-infested plants and weeds also belong in the organic waste bin if hot composting is not possible in your own garden. Neophytes (invasive plant species) such as mugwort ambrosia or giant hogweed are best disposed of in the residual waste.
Paper
Paper in large quantities belongs in the waste paper collection and not on the compost heap. Printed paper, especially wrapping paper, can be contaminated with heavy metals.
Setting up the compost
In general
The more diverse the composition of the organic material and the more optimal the conditions for the composting process, the better.
Shredding
To support the microorganisms in their work, it is a good idea to shred the organic material as much as possible. The microorganisms can decompose the previously shredded material more quickly. The composting process is accelerated.
Mixing
For optimal conditions in the compost you need a good mixing ratio.
The following applies:
- Mix dry and moist material together.
- Mix coarse and fine material together.
- Mix deposited and fresh material together.
- Mix nitrogen-rich and nitrogen-poor material together.
Carbon (C) – Nitrogen (N) – ratio
For composting to succeed, the microorganisms need both carbon and nitrogen in a ratio of about 20:1 (C:N). This means that for every 20 parts of carbon there is 1 part of nitrogen. The organic materials have different proportions of carbon and nitrogen. A balanced carbon-nitrogen ratio can be achieved by mixing, by weight, 20 parts of carbon with each part of nitrogen.
The trick is to find the right ratio, because if the material contains too little nitrogen, composting is very slow and can take years. If there is too much nitrogen, i.e. if the material is too fresh and too wet, composting will not get off the ground. The compost may even rot.
Aeration
To ensure that the compost is well aerated, you should place the material in an uneven layer. It is important to mix coarse material with fine material. Only in this way can the microorganisms work well and multiply sufficiently.
Moisture
Make sure that your compost does not dry out. If the starting material is too dry, you can mix it with moist materials such as kitchen waste or grass cuttings, but you may have to water the compost. You can use normal water or urine diluted with water (urine-water 1:4).
PH range
Microorganisms thrive in a slightly acidic to slightly alkaline environment, i.e. a pH range around 7. This value will adjust itself if the compost is set up correctly. You can determine the pH value using litmus paper.
The Three-compartment composter
Making compost
If you have enough material for at least 35.3 cubic feet of compost, you can make the compost in one go. If there is not enough material, you can slowly build up your compost layer by layer over a longer period of time.
Both options produce good compost. The only difference is the composting method. If the compost is built up layer by layer, it goes through cold rotting, while the compost that is made all at once rots according to the hot composting method (see also -> Composting methods).
Three-chamber composter
A three-chamber composter is well suited for a medium-sized garden and is our favorite. The new compost heap is placed in the first chamber. You can use the second chamber for moving the compost. The third chamber is for storing the finished compost.
You start by placing the new compost in the first chamber. The first layer consists of course-textured material, such as shredded branches and twigs. This layer should be about 9.84 inches high. It is important that this first layer is placed loosely and consists of coarse material. This is because this layer allows excess water to drain out of the compost and prevents it from starting to rot. For the second layer, mix nutrient-rich, moist and soft materials such as vegetable and fruit waste with nutrient-poor, dry and stable materials such as shredded shrub stems, branches, twigs and unrotted components of an old compost. When this layer has reached a height of about 7.87 inches, cover it with a 1.97 inch thin layer of manure.
Now, add another 1.97 inch layer of a mixture of compost from the trunk, garden soil and primary rock flour. On top of this layer you put another 7.87 inch high mixed layer, followed by a 1.97 inch layer of manure and a 1.97 inch layer of a stem compost-garden soil-primordial rock flour mixture. Now cover this layer with a mixture of grass cuttings, vegetable waste and leaves (approx. 3.94 inches). The final layer is a 1.97 inch layer of garden soil. If your compost material is too dry, each layer should be watered or watered with diluted urine (urine-water 1:4). It is best to use a watering can for watering. Finally, cover the compost.
If you have a composter without a lid, you can use compost fleece. The cover protects the compost from rain. Nutrients are not washed out and remain in the compost. It also keeps the heat in the compost. The cover can also help to keep fruit flies and other animals such as rats or mice away from the compost.
Compost additives
Compost starters usually contain organic nitrogen, bacteria and fungi. In moist compost they become active and are involved in the composting process. However, they can only develop their effect when the right conditions prevail in the compost, i.e. the compost consists of a good mixture of organic materials, is loosely composted and contains sufficient oxygen. If this is the case, the rotting process will proceed without the help of compost starters.
Please Note
A well established compost does not need any compost additives or finished compost accelerators.
If you want to get composting going quickly, it is a good idea to „inoculate“ the compost, i.e. add a few shovels of stem compost (older compost) to the new compost.
Some additives can help you regulate the compost, for example if it is too acidic, too wet or too low in nitrogen.
If your compost contains a lot of lawn clippings, coniferous wood and needles, adding lime (e.g. algal lime) can be helpful (0.125 lbs/ft³) to bind the acid released during the composting of these materials.
If your compost is too wet, you can improve it by adding primary rock flour (0.125 to 0.188 lbs/ft³) to alleviate the problem.
If your compost is mostly composed of low-nitrogen materials such as wood chips or straw, you can balance it out by adding nitrogen-rich materials such as manure or fresh grass cuttings.
Composting methods
Hot composting
If you have the option of making compost in one go, as described above, it has the advantage that the individual stages of rotting take place simultaneously throughout the compost material. The compost can heat up to temperatures between 140°F and 158°F. A large compost can hold the heat for several weeks. This can kill pathogens, germs and weed seeds.
Cold composting
In many small, private gardens, too little organic material accumulates at once, so the compost is built up slowly, layer by layer. The rotting stages in the layers therefore also take place one after the other. This means that the layers can have different stages. In each case, the most heat is generated in the uppermost layer; in comparison to the hot compost, temperatures of up to 104°F are usually only generated here due to the rather small compost volume and the associated lower activity of the microorganisms. Since the layer is not insulated, it cannot hold the heat for long and cools down again quickly. The compost therefore takes much longer to mature.
Please Note
Due to the low temperatures, cold rotting cannot ensure that pathogens and weed seeds are completely killed.
Composting process
The composting process takes place in four stages: mesophilic, thermophilic, cooling, and curing. The stages cannot always be precisely delineated. For the composting process to proceed as described below, a minimum compost size of about 264.17 gallons is required. The compost must also have been built up all at once.
Stage 1: The Mesophilic Phase
The first stage is fast (within a few weeks). Mesophilic (medium temperature-loving) microorganisms break down easily soluble compounds (proteins, sugars and fats). Ideal conditions in the compost contribute to the rapid multiplication of the organisms. The temperature in the compost rises to over 122°F. The metabolic activity of the microorganisms generates heat. Since the rotting process can only conduct the heat poorly, the heat accumulates in the compost. Hygienization begins. In addition to heat, thermophilic (high temperature-loving) microorganisms and their metabolic products are involved in hygienization. Weed seeds, pests and disease germs are therefore killed. Residues of pesticides and antibiotics are also decomposed. If the compost is composed of a sufficient amount (at least 264.17 U.S. gallons) of well-mixed organic material, the temperatures rise up to 158°F. Afterwards, the temperatures drop again.
The organic material is now broken down into its basic building blocks. The decomposing organisms die and serve as food for other organisms. The rot has turned from green to brown/black-brown.
Stage 2: The Thermophilic Phase
Now, in addition to mesophilic bacteria, fungi that specialize in breaking down substances that are difficult to utilize, such as cellulose and lignins, are active in the compost. The temperature drops again to 86 to 113°F.
Stage 3: The Cooling Phase
Humic substances are formed. Fungal growth decreases. Small soil animals such as mites, springtails, beetles, woodlice, dungworms and compost worms migrate into the compost and ensure that mineral and organic parts are mixed together. Stable crumbs are formed (clay-humus complex).
Stage 4: The Curing Phase
Humus formation and mineralization are completed. The compost worms leave the compost. Mature compost is formed. The humic substances give it a dark brown color. The material is now loose and crumbly, indicating the completion of composting. The original material is no longer recognizable as such, except for pieces of wood and woody stems. (You can sieve out the wood pieces and add them to the next compost).
Hygienization and pasteurization
While plant material can be composted more or less safely, feces can contain germs and pathogens that are harmful to human health.
Here, the focus is on your own responsible action. The legislator assumes that you have an interest in spreading a low-pollutant and hygienically safe, high-quality compost on your beds and that you therefore choose the organic source materials for your compost carefully and compost them properly and, if necessary, sanitize them.
Composting is properly sanitized when the following conditions are met:
- The water content is at least 40% over the entire period.
- The pH value is around 7 over the entire period.
- In the compost, temperatures of at least 131°F prevail continuously for 2 weeks, or temperatures of 140°F continuously for 6 days or temperatures of 149°F for 3 days.
However, the temperatures required for hygienization only occur during hot composting. For this, as already described, the compost must have a certain volume and be placed in one piece. If the compost is placed layer by layer, the compost will not develop the required temperatures.
In the case of self-composting by hot composting, there is also the following difficulty. While you can control the temperature and pH with a compost thermometer and litmus paper, you will have difficulties to find out the exact water content of the compost. Therefore, when composting on your own, it is difficult to check whether the prescribed conditions for proper hygienization have actually been met.
The WHO recommendation
The WHO (World Health Organization) therefore recommends composting for a period of two years. Since the compost poses a health risk during this period, filling and handling of the compost must be carried out under hygienic aspects, according to the WHO.
Monitoring composting
In order for composting to proceed quickly and without problems, favorable conditions must prevail in the compost. Therefore, you should monitor the temperature, moisture and acidity during the composting process.
Temperature
Particularly in hot composting, monitoring the compost temperature is indispensable. With a compost thermometer (see also useful tools) you can measure the temperature in the compost directly and lower or raise the temperature if necessary. Adding fresh grass cuttings can increase the temperature. By watering the compost you can ensure that the temperature in the compost drops.
Moisture
During the decomposition phase and in summer there is a risk that the compost will dry out. In fall and winter, when it rains a lot, you should make sure that it does not get too wet. The compost should be moist, but never wet. With the fist test you can quickly and easily determine the moisture content of the compost. Correct moisture: When you squeeze the rotting material in your fist, only a few drops come out. If you open your hand, the material will hold together. Too wet: When you squeeze the rotting material in your fist, water flows out of the material. Too dry: No water comes out when you squeeze the rotting material in your fist. If you open your hand, the material falls apart, like sand.
Oxygen
If the rotting material smells earthy and like fresh forest soil, there is sufficient oxygen in the compost. If the material smells rotten or sour, there is a lack of oxygen in the compost.
The compost loses volume (approx. 50 %) in the composting process and sinks. Accordingly, there are now fewer cavities in the compost.
Water can no longer evaporate as well and oxygen can no longer be supplied to the compost well. There is a danger that some areas in the compost will remain without oxygen and anaerobic processes will take place here. This must be avoided, as rotting could occur.
Unlike rotting, which releases carbon dioxide, water, humic substances and trace elements, putrefaction produces gases that are harmful to the climate, such as methane and nitrous oxide. Rotten compost is not only useless because it does not form humus, but it is also harmful to the climate.
Possible problems and measures
Below we have compiled a table with possible problems that could occur and the corresponding measures.
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Compost is too dry.
Transfer and water compost and/or add fresh lawn cuttings.
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Compost is too wet, smells putrid.
Turn compost and add dry material such as straw and/or wood chippings, if necessary also add some primary rock flour.
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Compost is too hot.
Turn compost and mix with soil.
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Compost does not become hot.
Add fresh lawn clippings
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Composting proceeds too slowly.
Turn compost, add nitrogen-rich materials such as kitchen waste and manure, water if necessary.
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Compost is full of fruit flies.
Cover fresh and rooted material with soil, loosen compost material, add primary rock flour if necessary.
Turning the compost
In the course of the composting process, the compost loses volume, it collapses. Hollow spaces that held the oxygen in the compost disappear. Oxygen deficiency occurs. For this reason you should turn the compost as often as possible, i.e. loosen it up with a digging fork and mix it. In this way you ensure that the compost material is well aerated again and at the same time you stimulate the activity of the microorganisms. The temperature in the compost increases again and composting is accelerated.
During turning, you can check the compost for moisture. Work the layers around the edges into the pile and water dry layers if necessary.
The compost should only be turned for the first time after the decomposition phase, when the temperature has dropped to approx. 113°F again. After that you can turn the compost several times. Do not turn the compost in winter.
Please Note
The more often compost is turned, the faster it can mature.
Use, spreading and storage of compost
Use
The rotting time has an influence on the use of the compost. Depending on the rotting progress (maturity), a distinction is made between fresh compost and mature compost.
Fresh compost
Fresh compost is approx. 3 to 4 months old and has not yet been completely transformed into compost humus. Compared to mature compost, it has a coarser structure and is colonized by soil organisms. In fall you can use fresh compost to mulch strawberries, berry bushes and hedges. It should not be used for sowing, as it inhibits seed germination and damages the roots of young plants. Fresh compost is not suitable for repotting houseplants or for planting balcony flowers.
Mature compost
After about 4 to 8 months, the compost is ripe. The dark brown, almost black mature compost has a loose, crumbly structure and smells like fresh forest soil. It is versatile and can be spread on both vegetable and flower beds. Mixed with soil (70 % garden soil and 30 % compost) you can use it for planting balcony flowers and repotting houseplants. To support the growth and health of the plants, it is advisable to always add a few shovels of compost when sowing.
Mature compost not only helps to rebuild depleted soils with nutrients, it also improves the structure of so-called „problem soils“ such as sandy, loamy or clay soils. Sandy soils can store water better, loamy soils get a looser structure and clay soils can be worked more easily.
Spreading
Compost should only be worked into the soil superficially, but not dug under.
It is recommended not to apply more than 0.79 gallons of compost per 10.76 square feet to the soils per year (the optimal amount can vary between 0.26 and 0.79 gallons per 10.76 square feet depending on the nutrient requirements of the respective crops). If the soils are depleted or if a garden or bed is newly established, then 22.05 lbs of compost per 10.76 square feet, i.e. a layer of 0.39 to 0.79 inches, can be applied once.
Please Note
Using compost as fertilizer is quite sufficient.
Storage
Mature compost should not be stored for more than one year, as nutrients are lost over time.
Cress test
With the cress test you can determine the degree of maturity of the compost. Mix one part garden soil with one part compost and put the mixture in a small bowl. Now scatter cress seeds evenly and place the bowl in a sunny spot, e.g. on the windowsill. Use a flower sprayer to keep the soil moist. The cress seeds should germinate after a few days.
If the cress germinates irregularly and the leaves are yellow, it is a sign that your compost is not yet ripe. If, on the other hand, you can observe regular germination and the leaves are strong and green, you can assume that your compost is ripe.
Useful tools
Digging fork
You can use the digging fork for turning the compost. It is also suitable for working the finished compost into the soil.
Pitchfork and shovel
With the help of a pitchfork or shovel, manure, mulch, and compost can be easily transported into a wheelbarrow.
Spade
You can use a spade to shred robust compost material, among other things.
Garden and hedge shears or shredder
Prunings from trees, hedges and shrubs can be shredded with garden shears or hedge trimmers to prepare the compost material. If you have a lot of material, you should consider buying a shredder.
Watering can
A watering can is a good way to water the compost.
Wheelbarrow
The wheelbarrow is not only suitable for transporting compost from A to B. You can also use it to transport many other garden materials such as soil, wood, leaves or garden tools.
Compost sieve
With a compost sieve you can easily sieve the finished compost. Pieces of wood and stalks that have not yet rotted can be easily sorted out.
Compost thermometer
A compost thermometer is important so that you can measure the temperature in the compost during composting. We recommend a stainless steel compost thermometer with a measuring probe at least 19.69 inches long. The thermometer should be able to display temperatures in the range of at least 32°F to 176°F.
The Bokashi Bucket – an alternative to compost
Bokashi originated in Japan. It offers a good alternative to compost. The organic material is collected in an airtight Bokashi bucket and sprayed with an EM solution. The EM solution contains Effective Microorganisms (lactic acid bacteria, yeast, photosynthesis bacteria) which ensure that the organic material in the bucket ferments. Within 2 weeks a liquid is produced that can be used as a liquid fertilizer. The fermented organic material is very acidic and first has to be„earthified“, i.e. mixed with soil (2/3 fermented material and 1/3 topsoil), before it can be used as fertilizer. The process of „digestion“ takes about 12 weeks.
In bokashi you can collect all organic kitchen waste. In addition to fruit and vegetable scraps, citrus peelings, coffee grounds, you can also add cooked food scraps such as pasta, rice, bread, small amounts of meat scraps, cold cuts and milk products to the bokashi bucket. Note that it takes a long time for the animal material to ferment. It is therefore recommended that cooked food scraps and organic waste of animal origin should rather be disposed of in the organic waste bin. There is also a risk that the fermented animal materials will attract vermin during the „digestion“ process.
If you don‘t want to compost your garden, a bokashi bucket is a good alternative to make your own environmentally friendly fertilizer.
