Berkeley compost

"Capture and store energy" is the second of David Holmgren's twelve permaculture principles. In short, this principle encourages us to return (maintain) unused energy (energy surplus) back to the system. We could find a wide range of activities where this principle can be applied. Today we will look at one of the most basic - the reuse of waste using, as the name suggests, a very efficient composting method.

Almost everything can be reused

It's April and spring is everywhere. The sun is warm, the days are much longer. And I firmly believe that you have all been working diligently in your gardens and fields since March. April is the month when most common vegetables and fruits are planted. April is the month when they are planted. Remember that growing your own food is like growing your own money. And besides, you grow food that differs diametrically in both quality and nutritional value from these - popularly speaking - chemically discarded supermarkets (from commercial agriculture).

So when you return to your gardens after the winter, the first thing that comes to mind as soon as the snow has fallen (if any has fallen) is that you do a proper cleaning. And here is a huge opportunity. Before you decide what to burn, what to throw in a (usually) built-in container, and what to keep, think of the accumulated waste as a material with a huge useful potential. It is estimated that up to 90 % garden waste, such as last year's dry leaves, grafting branches, dry grass, broken tree branches, various wood and wooden objects, paper, etc., can be reused. Divide the pile into organic waste and the rest. All organic material that comes from plant or animal production. It is generally called biomass and has a wide range of uses as a potential energy source. It has practically everything, including secondary products. So even the old handle from your rakes that you're about to burn.

The remaining 10 %s are usually plastics (various boxes, broken flower pots, garden tool handles, cable ties, various packaging, containers, etc.), metals (old nails, various fasteners, cans, etc.), glass and chemicals (if you are some came). So if you can't find any other use for junk from your pile, recycle it. And you don't have to end up with garden waste. Other numbers estimate that up to 40 % household waste can also be composted.

Healthy compost, healthy garden

In the last issue, Mr. José brought a nice article on how to prepare a quality growing medium for different environments. He mentioned the individual alternatives to fertilization and came across the use of compost. Compost is an important, perhaps even essential, part of every garden (any). It helps us return surpluses back to the system in the form of soil. Keeps the soil (garden) healthy and fertile. It is actually a mix of all sorts of biological material and waste, which is subject to decomposition by means of soil-forming processes, thus creating a very nutrient-rich soil mixture, which is used for fertilization. But what if you don't have compost? Or you only established the so-called "cold compost" last year, so you will not receive the first proceeds until this year and it will be no glory. Or you have compost, but you still need more substrate. Don't spend money in gardening and try the "hot variant".

The old method

As I have already indicated a few lines above, we can find more common so-called "cold compost" or (not so much less) less common "warm compost". Both methods have their advantages and disadvantages. The cold one is very familiar to everyone. This is so-called passive composting. Everything compostable simply accumulates in one pile and we let time work. However, we will not see the first yield for a year. The main advantage of this method is that we do not have to do almost any physical work. Everything happens pretty much on its own, but it takes time. The big disadvantage is that precipitation can significantly reduce the content of important nutrients that are washed away. Another is that weed and pathogenic contamination is relatively difficult to control. It is therefore important to think carefully about the location of the compost. And no less important is what you put into it. If you can deal with these ailments, the resulting product is usually more than satisfactory.

Hot compost and how to make it

It is worth mentioning the document Permaculture Soils (2010), in which Australian Geoff Lawton, an international permaculture designer and instructor, guides the viewer very engagingly through the entire preparation process to the final product.

However, the method was first introduced by prof. Robert D. Raab, who works at the University of California, Berkeley. Hence its official name - Berkeley compost. You can also come across other names such as the Berkeley method, fast composting and the already mentioned hot compost. All these variants of naming reveal the basic characteristics. This is a relatively fast (2-3 weeks) and efficient process of composting with heat. But let's not get ahead of ourselves.

Before you start working, you need to be aware of several factors. These have exactly the same meaning and none of them should be neglected. So I recommend reading the individual points at once before you start doing anything.

The key to success is a well-prepared raw material

All material needs to be chopped, crushed or chopped. Only parts no larger than half to one inch (approx. 1.25 - 2.5 cm) are easily composted. The soft and fleshy tissues of plants decompose the fastest and need to be chopped into really small pieces. The wood material should be driven by a shredder to ensure good comminution, which is desirable. Avoid using the shredder on herbal material and prefer chopping, because the shredder will grind such material too finely. This can cause decomposition too quickly and volume loss.


Keep in mind that you should have about 5 m available for comfortable turning of the compost2 surfaces preferably with a clay suffocated base, where you will need to shuffle the pile from one side to the other. When installing it, it is important that air is not blocked from below. During decomposition, aerobic processes occur and it is necessary to maintain free access to oxygen.

Carbon versus nitrogen

To achieve the most effective result, it is necessary to keep the ratio of carbon and nitrogen C: N 30: 1. This ensures proper metabolism and energy consumption during the process.

Keep in mind that nitrogen, or nitrogen material, is the "fuel" and activator in one. A large supply of nitrogen is due to composting too fast, accompanied by an undesirable loss of volume and odor caused by the release of methane. Nitrogen sources include all green material (fresh grass, weeds, vegetable and fruit waste, waste from your kitchen, etc.) Another and very important source of nitrogen and fuel is manure. As for adding manure, opinions differ a little here.

Geoff Lawton boldly recommends adding any manure produced by herbivores. And he adds that you don't have to be afraid to add duck manure, poultry, pig or even human. In any case, the mixture must be used sparingly, because it is only a so-called soil bacterial stock. The C: N ratio must be observed (see figure). Lawton states that if you use a mix of different types of carrots, you will get a very diverse set of minerals that are very important for a healthy plant. However, Raab clearly does not recommend the use of manure produced by omnivores or carnivores, or human manure (if you own a composting toilet). This decision is entirely up to you. It is important to find out a little more about this. The reason is that such "fresh" manure can contain various pathogens that can infect humans. It is almost certain that high temperatures will kill all potential pathogens. Still, if you decide to use such manure, be sure of what you are doing.

The carbon source is actually all the material mentioned in the introduction to the article. So your spring cleaning can potentially produce enough raw material for you. And you don't have to end up here. If you find that you still do not have enough material to reach the minimum volume (see Temperature), top it up with dry straw, grass or mulch. Don't be afraid to use old newspapers, cardboards, paper bags, boxes, etc. But keep in mind that everything must be well chopped / sliced and perfectly mixed.


Low or high humidity is undesirable in both cases and the result will be that it will not "start" the composting process. The ideal humidity of the heap is about 50 %. This, of course, is poorly measured. According to Lawton, the ideal test is to take the ideal sample (so that it just fits in both palms) and squeeze it with all your might (not to squeeze). Water should just start dripping from it.


As organic material decomposes, heat is generated. This is the result of respiration of microorganisms during their "work". In order for the heat to be retained and for the heap to be able to heat up at all, the minimum volume needs to be at least one cubic meter. If there is more, it doesn't matter. In the temperature, the two gentlemen part again. They match at least on a scale of 55 ° C - 70 ° C. Lawton still prefers to keep the temperature between 55 ° C - 65 ° C. In its study, Raab assures that the temperature can safely rise to the upper limit, which it must not exceed. Otherwise, all important microorganisms will be killed. And that means the end of all efforts. I personally lean towards Lawton, who chooses the golden mean. So how do you find the desired temperature if you don't have a thermometer? The most effective is to use a practical test, which consists in immersing the hand in a pile. If you put your hand up to about 60 ° C, you will simply pull away, because it is already a relatively hot environment for our body. And you won't even want to put your hand up to 70 ° C, as you would risk scalding. You will feel such heat immediately, already during the excavation of the probe. Maintaining the temperature is very important. So make sure that the compost is well protected from rain, which could cool it down. Simply cover it with tarpaulin or sackcloth, for example.

Three weeks

To prevent the compost from overheating, it is important to turn it over regularly. The basic time interval is 18 days. The first overturning is done on the fourth day, when the compost should reach its maximum temperature, and then every other day until the 18th day. The compost must be turned over so that the hot center reaches the cooler edge (see figure). From there, continue in the same way until the temperature of the compost drops. In the end, the heap should remain slightly warm. It should be done by day 21 at the latest.

It is not possible without work

Finally, I will highlight some of the benefits of hot composting. Compared to the cold method, as already indicated in the introduction, with this method you will get the product in a relatively short time. But as you can already guess, it won't be completely free. There is a lot of physical work required to prepare and during the process. Personally, I don't consider it a disadvantage, because you get along well. So for that day, you can safely skip getting upset in a traffic jam on the way to your favorite gym. However, the great benefit of this method is that virtually anything that is compostable can be composted. Furthermore, you do not have to worry about contamination by pathogens or weeds, because everything is destroyed by the heat generated - "burned" (but be careful here! See the use of different types of manure). And last but not least, the volume of the final product is almost the same (should not be different) from the volume of the inserted material, unlike the cold method, where the volume can be reduced by up to two thirds. And what's more? Berkeley compost can easily cope with mild toxicity. So don't be afraid to throw the once painted rake handle at all. Have fun.


  1. The Rapid Composting Method, Robert D. Raabe, Professor of Plant Pathology, Berkeley, University of California (pdf version)
  2. Hot Composting with the Berkeley Method, Kate Atchley, Student Intern, August 2013 (pdf version)
  3. Permaculture Soils, documentary, 30 October 2010 (Australia