dimanche 25 juin 2017

108- Agroecology -5- (Urban agriculture -2-) - Composting


Making your own compost is one of the best ways to reduce the volume of organic waste, while preparing an excellent fertilizer for your crop or your garden.

In woody crops it is normal, but not generalized, to grind the wood from pruning, to leave it on the spot, restoring to the soil the majority of mineral elements extracted by plants. This practice of grinding, with or without burial, is also practiced in many annual crops.
But some situations may require that this grinding is not carried out. This is the case of certain diseases, or the requirements of certain types of mechanization (such as the harvesting of almonds). There are also farmers who simply don't want to do it or are not equipped with grinders.

In these situations, the most common practice is to get the wood out of the plot using a large rake harnessed to a tractor, and burn it.
It is an economical and rapid technique, but burning is an agronomic, energy, nutritional, environmental and even economic contradiction, at least in areas with temperate climates. Indeed, the benefits of the contributions of organic matter are numerous (see http://culturagriculture.blogspot.com.es/2015/10/54-organic-matter-in-soil.html). To systematically burn this source of restitution accelerates the impoverishment of the agricultural soil and forces the farmer to purchase considerably superior quantities of fertilizers to what he would need by restoring this organic matter.

In situations where local grinding of plant remains is not done, the best solution is composting. These remains are collected on an open area, coarsely grinded, organized in piles, wetted and stirred periodically.

The process is simple, economical, but requires some organization and rigor. Composting in pile will go through a thermophilic phase, during which the core temperature can reach 70ºC for a few days, producing a sterilizing effect by eliminating almost all fungi, bacteria and insects. Even coming from diseased plants, composted vegetal remains are transformed into a healthy and economical source of organic matter, and thus an organic fertilizer for crops.

In some areas, there are groups or companies specialized in the collection of strictly plant remnants (especially of urban origin), to transport them to farms where farmers become owners of them and process them by composting for their own use. Waste collectors see volumes to be treated reduced, farmers obtain an amount of plant remains that they are unable to produce on their farms, and they make their own organic fertilizer.
I have a friend and former colleague adviser who specialized in this activity, in Provence, by creating the company Terre et Compost. Hi Eric!
If the composting has a good quality and the plant remains too, the compost obtained can even obtain the organic label (but it depends mainly on the national legislation).

Composting is a very old technique, simple, economic and ecological to dispose of high quality organic matter on the farm.

I found an interesting article on this subject on a French-speaking Facebook page (from Quebec, therefore from the French-speaking part of Canada), highly recommended to all those interested in soils, Sols Vivants Québec (https://www.facebook.com/groups/1643973612487835/?ref=group_header). You will find a lot of information, with a dose of science, a dose of lived experiences and a good dose of ideology and militancy. Everyone will be able to find their account. I don't always agree with the ideas, but it does not detract from the interest of most publications.

The following text was published on Agronouvelles.com, the blog of the Agronomists Board of Québec http://www.agronouvelles.com/2017/06/le-compostage-domestique-passion-volonte-and-knowledge-techniques-requises/  

"Domestic composting: passion, will and technical knowledge required.

Composting is a fascinating field that is practiced at large, medium and small scale and is aimed at industrialists, agricultural producers and amateur gardeners alike. In short, to all those interested in the environment, agriculture or horticulture.

While urban agriculture is attracting an increasing attention, domestic composting is still part of the tools that are available to the urban horticulturist as a mode of production of living matter (the compost) and more recently, from an environmental perspective, as a mode of ecological management for certain residues generated at home.

In so doing, the transport of these organic materials and all the disadvantages and the impacts that it entails are thus minimized. Using compost at home, organic matter and nutrients essential for plant growth are returned to the soil. In spite of these noble objectives, it takes horticultural passion, environmental convictions, a bit of will, and a minimum of time and technical knowledge to make domestic composting a perennial adventure.

What is composting?

It is often argued that composting is a natural process. Despite the similarities we see between composting in pile and decomposition processes observed in nature, we must note that the stacking over several feet of organic matter of various origins that is placed on a limited surface or in a closed place does not occur in nature.

Composting should therefore be seen as a process that is controlled and is different from a pile in the field or from a stack of organic residues that we let be decomposed and which, over the course of months and years, ends being transformed into a material that seems to be black earth.

In specialized literature such as standards and guides, composting is synonymous with "a directed process of bio-oxidation of a solid organic substrate including a thermophilic phase". This definition implies maintaining aerobic conditions within the mass and achieving thermophilic temperatures (corresponding to Tº> 45ºC) throughout the mass. This notion of reaching high temperatures is important, in particular for large-scale composting, because it makes possible to obtain a hygienisation effect. Thanks to the high temperatures, the composting process reduces the level of pathogenic micro-organisms and the destruction of weed seeds, reducing the risk of contamination and spread. The term "compost" should logically be understood as the product obtained from composting, i.e. a stabilized, hygienized and deodorized material that is beneficial to plant growth.

Should it be deduced that compost from domestic composting without temperature rise is not of quality? Absolutely not! By following the rules of the art, it is possible to produce a compost of good quality; It is necessary, like in the case of production of wines or beers at home, to take the trouble to learn, because there is a limit to be able to reconcile ease and quality when processes involved are complex.

Small scale composting

Composting at different scales and the use of composts have been the subject of numerous books and publications. Here in Quebec, the recent book entitled "Le compost: Pourquoi? Comment?" (Compost: Why? How?) of the agronomist Lili Michaud addresses the subject in a clear and detailed way and provides a wealth of useful, if not essential, information for those interested in domestic composting. It is unnecessary, therefore, to repeat here information already amply dealt with.

Regardless of the scale at which composting is practiced, the processes that involve the work of micro-organisms are the same and the purpose of the composter is to satisfy the requirements of the micro-organisms so that the work is adequately carried out. If micro-organisms don't care about the size of operations, they need a good environment (moisture, oxygen) and food (carbon, nitrogen) to do their jobs and survive in the microbial jungle.

The choice of quality residues is crucial and this is especially true in the absence of high temperatures. This mode of "cold" transformation requires a minimum of vigilance. For example, materials that may contain pathogens (animal feces, diseased plants) and plants considered to be weeds (rhizomes or seeds) should be avoided.

Furthermore, for reasons of quality, materials that may contain metals or non-biologically degradable compounds (e.g. pesticide residues, treated wood ash, plastics) or materials that generate unpleasant odors (for you and for your neighbors) such as fish, meat and crustaceans are also to be avoided for small-scale operations. Finally, some materials can be composted, but in small quantities (eggshells, moist fresh grass, ash).

Compost is primarily an organic soil amendment and is advantageously used primarily as a source of organic matter which, by decomposing in the soil, will provide the nutrients essential for plant growth. The quality of composts is a complex field, both in the multitude of parameters to be taken into consideration and in the complexity of the processes involved, from the compost to its use.

A greying teacher once said to a young agronomist: "Know that it takes more than a thermometer to do composting." It's my turn to say, "It takes more than a pH meter to assess the quality of the compost."

Organic matter content, humus, water retention capacity, C/N ratio, nitrogen, phosphorus, potassium, oligoelements, pH, maturity and pathogens are just a few examples of the terminology associated with the concept of quality of composts.

These parameters are important for those whose job is to ensure good plant growth while preserving the quality of the soil and the environment. Welcome to the agronomists beds!

Agronomist since 1982, Denis Potvin [author of the article] is specialized in the management of biomass and fertilizer residual materials of various origins, notably by composting. He joined the Institute for Research and Development in Agri-Environment (IRDA) in 2012 as project manager for biomass recovery. Denis Potvin now works as a technology transfer agent while continuing to be involved in projects that bring his expertise to bear."

If you want to make your own compost, learn more about the process. It's simple, but there are a few rules to follow.
You will find many useful links, for example by typing on your search engine "make your own compost".

At work!

Picture: https://verslautonomie.files.wordpress.com/2013/03/dsc00118-compost.jpg  

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