One of the environmental problems of farms are the organic waste from pruning, harvesting, post-harvest, manure, grass, fallen fruit, among others. Normally, due to ignorance, lack of adequate space, or time, the common practice with these wastes is burning, burying or abandoning them out in the open until rot.
Composting provides the chance to safely transform organic waste into inputs for agricultural production. FAO defines composting as the mixture of organic matter digested aerobically that is used to improve soil structure and provide nutrients.
However, not all materials that have been transformed aerobically are considered compost. The composting process includes several phases that must be met to obtain quality compost. The use of a material that has not successfully completed the composting process (raw or only stabilized).
• Phytotoxicity. In a material that has not finished the composting process adequately, nitrogen is in the form of ammonium instead of nitrate. Ammonium in hot and humid conditions is transformed into ammonia, creating a toxic environment for plant growth, resulting in odours. Similarly, unfinished compost contains unstable volatile chemicals such as organic acids that are toxic to seeds and plants.
• The biological block of nitrogen, also known as “nitrogen starvation”. Occurs in materials that have not reached a balanced C:N ratio and are far richer in carbon than in nitrogen. When applied to soil, microorganisms quickly use de C present in the material increasing the consumption of N and exhausting the reserves of N.
• Root oxygen reduction. When material in the decay phase is applied to soil, microorganisms will use the oxygen of the soil to continue the process, exhausting it and not making it available to plants.
• Excess ammonium and nitrate in plants and contamination of water sources. A material with excess nitrogen in the form of ammonium tends to lose it by infiltration into the soil or volatilization and contributes to contaminate trickling and underground water. Likewise, it can also be taken by the crop, producing an excessive accumulation of nitrates, with negative consequences on the quality of fruit (softening, short post-harvest time) and human health (especially leafy vegetables)