Composting biowaste and the application of compost play an important role in sustainable agriculture. Composting allows organic waste to be recycled and returned to the soil and provides a solution for managing much of the waste, which is currently a major problem. If urban organic waste is selectively collected and composted, it no longer represents a problem. Composting provides an excellent way to manage the huge volume of organic waste and convert it into a useful soil amendment. This approach could have practical significance in reducing the use of chemical fertilizers for sustainable agriculture and the environment. The application of enriched compost with N increased the aggregate stability of the soil (Ahmad et al. 2008). The impact of organic amendments and compost extracts in organic vegetable production systems improves soil health (Ghorbani et al. 2008). Hachicha et al. (2006) reports that the compost made of poultry manure and olive mill by-products appears as a promising ecological alternative material to classical fertilizers. Compost will enrich the soil, thus promoting the preservation or improvement of the organic matter reserves of the soil, which is an important component of the soil protection strategy of the EU.

Composting is a complex chemical and biochemical process, during which a series of chemical transformations takes place in organic (bio- or green) wastes. In the course of composting, the decomposition of organic matter takes place in the presence of oxygen with the aid of various microorganisms and invertebrates. The majority of the biological transformations take place via enzyme-catalyzed reactions. From the soil biology point of view, composting is equivalent to rotting, the process whereby organic matter is mineralized, or in come cases humified, with the help of aerobic microorganisms. The end-product of this process is compost, a mixture of stabilized organic matter, mineral nutrients, and microbial products. This end-product should be of a quality that requires no further treatment prior to storage or utilization, and can be used in agriculture or horticulture without any danger to the environment.

In the course of composting the organic matter is stabilized with the help of microorganisms, leading to changes that are beneficial for soil fertility: the use of compost improves the biological activity and nutrient-adsorbing ability of the soil, the acids and microorganisms evolving during humus decomposition make largely insoluble mineral nutrients available to plants, hormone-like compounds stimulate plant growth, and the plants become more resistant to pathogens and pests.

However, if the raw materials are contaminated or the composting process is incomplete, unfavorable effects must be expected. Heavy metals may be introduced into the compost with communal waste. To ensure that these do not enter the food chain, authorised limit values must be strictly adhered to. The same is true of organic contaminants (particularly polyaromatic or chlorinated hydrocarbons), the effect of which is extremely complex. If the fermentation process is not satisfactory, putrefaction will occur, the by-products of which (SO2, NH3, NO2, organic acids, cadaveric alkaloids, etc.) inhibit plant growth and attract pests.

The composting process is an excellent means of recycling, as it reduces the mass and volume of the waste, while inactivating or destroying pathogenic microorganisms, viruses, and parasites, and improving the smell of the waste. The compost thus produced is a valuable form of fertilizer, which increases the organic matter content of the soil, stimulates biological activity, and improves soil texture. The recycling process is complete, as biological waste arises from plant biomass, which extracts nutrients from the soil, while these are returned to the soil when compost is applied as fertilizer.

Organic Gardeners Composting

Organic Gardeners Composting

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