Composting is a biological process of conversion and enhancement of organic matter (byproducts of biomass, organic waste of biological origin, etc.) into a stable, hygienic, like a soil rich in humic compounds, compost.
What waste compost?
Virtually all waste (leftover food, peel fruits and vegetables, bread, coffee and marc filters, eggshells…) are compostable. However, it is inadvisable to include compost leftover meat and fish, as they may attract insects and rodents, and cause bad smells.
The garden waste (grass clippings, wilted flowers, leaves…) can also be composted.
The important thing is to make waste varied:
- Waste green and wet kitchen for the contribution of water;
- Dry waste;
- Coarse waste to allow aeration of the whole;
- And although the mix.
Regardless of the technique used, the principle is always the same, we must ensure that microorganisms have the ideal conditions to grow and to decompose organic matter. We must take into account the following parameters:
1) Ventilation 2) Moisture 3) The report carbon / nitrogen 4) Good management
The golden rules of composting are explained in Part How does it work if it has not already done so, will soon consult.
The techniques described here are the most commonly used at the level of individuals. They are simple and do not require costly investment, nor sensitive operations or great effort.
The various methods of composting
The methods described below relate only to the phase of active fermentation. The maturation phase for its usually takes place in the open air in a pile large.
In the open air
It however will construct a canopy above the composts in fermentation to protect them from excessive rains or drying by the wind and the sun.
The method of composting pit in practice is the oldest employee but quickly leads to anaerobic conditions. The pit is dug in a sheltered place, well isolated. Organic waste are arranged in layers of about twenty centimeters thick, alternating products high in nitrogen (type 'N') and those rich in carbon (type 'C'). They are then covered with a thick layer of straw (insulation) and then a layer of soil about 10 cm thick. This method is very slow and anaerobic partly because no subsequent intake of water or air is made. It is reserved for amateurism and climates costs (better insulation) or dried (reduction of water losses). In a temperate climate, this method causes the appearance of odors (anaerobic decomposition).
It is the method of composting the most common. The wastes are collected in windrows of indefinite length and the height of which depends on both the porosity to air compost (the higher it is, type 'P', the job may be high), as well as the frequency and the method chosen ventilation (a high frequency and / or by forced ventilation vents allow a lot more important).
This method is very similar to the previous one, but the windrows are here between two side walls. She sometimes allows an installation easier venting devices but requires greater investment. There is also less flexibility for the organization or change the yard composting.
In total enclosure or 'digester'
The common principle of fermentation processes so-called 'fast track' is based on the stay more or less rapid waste in devices called digesters. A digester is a closed within which it is possible to monitor the progress of fermentation by acting mainly on aeration. Waste usually by entering one end of the device and emerged, after fermentation, at the other end. Brewing and ventilation materials are most often performed continuously.
Silo vertical (tower)
Many devices exist, more or less complex, but the principle remains the same. The waste is transported via a conveyor belt, at the top of the tower digestion. They alight either through auger or pigging following a succession of podiums, or by gravity. At each level, or in the mass of compost are installed ventilation pipes for oxygen to the environment. At the end of fermentation, the compost is collected at the base of the tower.
The digester is prepared here, rather than vertically, but horizontally. It is in fact a rotating cylinder with a length of 25 to 35 meters and a diameter of 3 to 4 meters. The continuous rotation of the cylinder, within which are fixed plates deflect helical, ensures both the mixing and aeration of the product and its progress towards the end of the device. The duration of stay of waste within the organic stabilizer is in the order of 4 to 6 days, after which they are transferred to the area of maturation.
As we have already indicated, aerate the compost mix is essential during active fermentation. Several methods exist, more suited to one or the other method of composting or a working scale greater or lesser extent.
Aeration passive and Chinese method
In traditional systems of composting in a pile, only the porosity of it ensures aeration of the estate. It is therefore limited to a lot of small-size and porosity of composts to very high (type 'P', large particles). The Chinese have improved the system by installing bamboo beams at the constitution of the heap. These bamboos are then removed after 1 or 2 days, leaving open apertures plunging until the middle of the pile and aeration which can be more actively.
Production of materials
The most efficient oxygenation of a mass warm fermentation is achieved by its reversal. The mix also ensures fermentation any more homogeneous mass, each particle moving enough time at the center of the compost, where the temperature is highest. Between the rollover, the outer portion of the pile evolves aerobically by passive ventilation (see preceding paragraph), while the percentage of oxygen in the center of the pile is decreasing rapidly. The frequency and quality of rollover accidents are the basic parameters of this technique.
Depending on the size of the composting site, will be brewing at the fork (manual labor), using a device of public works (shovel wheel loader), or using specialized equipment.
Aeration active blower
Unlike previous techniques, the flow of oxygen during fermentation is continuing. The windrows to vent cover a network of perforated pipes throughout their length and are connected to a booster. The power booster is based on the volume and the decrease in mass ventilate.
Aeration active aspiration (method Beltsville)
The supply of fresh air is performed here by suction through the windrows following a pattern identical to that of the previous method (except that the booster is replaced by a vacuum cleaner). The aspiration was to be preferred to that by wind tunnel because the air inlet was less inclined to borrow preferential paths, which would be detrimental to the effectiveness of the ventilation. It will, however, a filter, which can be simply a mature compost heap at the exit of the vacuum to eliminate odors. The breakdown can be combined, if desired, mixing with the material described above.
Determination of the end of composting
A good compost is a product whose organic components have undergone a conversion biological substances less aggressive and more stable. The degradation process, however, persist at a rate smaller even beyond the stage of fermentation. Therefore, when and for what purpose can be used safely compost phytotoxicity.
A fresh compost, having suffered a beginning of fermentation (around 2 weeks), can be used in mulching (mulching) or mushroom. At the end of fermentation, the compost is stabilized and can be used as fertilizer / organic amendment. A use as a substrate culture requires for its compost having undergone a long period of maturation (even longer than the plants are sensitive young seedlings, lettuce, ...).
A simple way to monitor the process of composting is, as noted above, using probes thermometers plunging into the mass fermentation. This method provides information on the stage of fermentation, but little on the level of maturity of compost. It should therefore be supplemented by one or more other methods
The consumption of organic carbon by the microflora frees large amounts of CO2. The gradual reduction of the carbon content in the middle has led to a significant decrease in the value of C / N. Indeed nitrogen fixed in the microbial protein, remains in the mass of compost (excluding losses by release of ammonia). Depending on the degree of fermenting carbon component residues, to be taken as a favorable C / N ratio of 20 to 40 at the end of maturation.
Many authors cite a C / N ratio of 15 to 30 as ideal. Practical experience shows that for substrates rich in lignin or other forms of low carbon fermentable a report of 40 or 50 does not cause failure by immobilization of nitrogen. The degradation of these carbon compounds by microorganisms is indeed much faster than the low-nitrogen consumption that results do not compete culture.
In addition to the C / N is determined chemically (method of analysis of the C / N). However, the chemicals do not correspond to the background of the enzyme microflora in the compost. On the other hand, the chemical analysis degrades completely particles in the sample, that is much more than the surface of attack immediately accessible for microbial enzymes. The C / N ratio will be ideal to be determined in each case.
Circular on paper chromatography
It was developed by PFEIFER (Biochemical Research Laboratory, Spring Valley-USA) and tested by HERTELENDY. Its principle is based on the fact that different substances, dissolved in the same solvent (NaOH solution at 5%), have affinities variables migration on a surface capillary absorbing (sheet round filter paper). This is pre-absorbent surface to silver nitrate, which serves as a revealing. The alkaline solution of compost is made drip at the center of the filter paper. After migration of the solution, we let the chromatogram develop in light softened. A compost changed little is characterized by a bleak picture on the periphery and a central spot clear; mature compost shows on the contrary, a central spot with dark streaks clear to the periphery.
Germination test plant
This is undoubtedly the easiest method and more reliable. The plants test most commonly used are Lepidium sativum and lettuce (Lactuca sativa). The seeds of the plant are sown test on the moistened compost jar tightly closed. After 3 days, maturity is judged according to the percentage of germination and possibly the amount of material obtained green.
Many other methods exist, more or less rapidly, more or less reliable, requiring an apparatus more or less expensive, and a staff more or less qualified. These include:
- Empirical criteria: color more or less dark, aspect of compost to the touch, the smell, ...
- Methods respirometrics: O2 consumption, CO2 emitted ...
- Physicochemical methods: determination of Chemical Oxygen Demand, dosage forms of inorganic nitrogen (NH4 + and NO3-), determination of SOD and the SOR (Substance Organic Decomposable and Substance Organic Resistant), pH measurement, ...
- Biological methods: determination of ATP (Adenosine Tri-Phosphate), growth of plants or microorganisms tests, ...
The compost can be used as fertilizer on grassland or before labor. Its use improves soil structure (input of organic matter), as well as the bioavailability of nutrients (nitrogen).
In the garden, it is used to fertilize the beds, fruit trees and vegetable garden. It can also be used as a breeding ground for pot plants.
The soil tilth
The first act of cultivation of land is to return its top layer to the loosening and airing to make it easily penetrable to the roots. At the same time, this transaction allows weeds in the burying and incorporate fertilizer and amendment.
The digging or manual ploughing consists, as its name indicates it, to cut out by means of a spade, successive strips of land in mounds which are rocked upside down in a trench called gauge. Out of heavy or stony ground, prefer the fork with tooth punts or fork digs, of easier penetration.
The depth of work is limited to the penetration of the iron of the tool, that is to say 20 with 30cm.
If the ground contains an appreciable percentage of clay, never work it when it sticks to the tool, owing to the fact that it is too wet: while drying again, it would take the consistency of the concrete. Take it in time, if possible before the rains of autumn.
Dig as much as possible before the strong frosts and do it with large mounds that you will leave intact without breaking them. By transforming into ice the water contained between the ground particles, the cold will make burst those and they will be exhausted easily in spring.
When you hide manure or manure, you do not satisfy to place them at the bottom of the gauge, but spread out them over the side of the latter: they will be thus much more regularly distributed in the ground.
To work with the minimum of effort, regularly sharpen the edge of your spade to the file tierce point and hold its own iron by scraping it with the scraper. Your digging will be more regular if you divide surface into successive bands from 2 to 3 meters of width. Always keep a gauge largely open in front of you to bury grass or manure conveniently.
Transplant the best possible underground rhizomes of long-lived grasses such as bindweed, grass, etc, as well as the large stones.
in the course of season, for the ploughings carried out between two cultures, dig less deeply but pulverize the mounds progressively.