Background

The way to sustainable management of natural resources is one of the greatest challenges of present time. The societies´ sustainability depends essentially on secured water resources, food supply and an intelligent management of wastes. Food, for example, is produced with extensive input of energy and resources. Nutrients are detracted from soils and need to be replaced. Replacement is often done by artificial fertilisers which are produced with high energy input. The reduction of organic matter content by the degradation of humus is mostly not replaced to the required extent.This leads to a slow but steady degradation of soil and loss of fertility. Urban sanitation systems nowadays, with their sewers and treatment plants, are not designed to close material cycles and extracted nutrients are not directed back to the soil. An analysis of a former civilisation in the Amazon, nowadays Brazil, reveals concepts which enable a highly efficient handling of organic wastes. Terra Preta do Indio is the anthropogenic black soil that was produced by ancient cultures through the conversion of biowaste and faecal matter into long-term fertile soils. These soils have maintained high amounts of organic carbon even several thousand years after they were abandoned. It was recently discovered that around 10% of the originally infertile soils in the Amazon region was converted this way from around 7,000 until 500 years ago. Due to the accumulation of charred biomass and other organic residues, terra preta subsequently formed giving it a deep, distinctly dark and highly fertile soil layer.One of the surprising facts is that this soil is highly productive without adding fertiliser. Recent research concludes that this culture had a superior sanitation and bio-waste system that was based on source separation of faecal matter, urine and clever additives particularly charcoal dust and treatment steps for the solids resulting in high yielding gardening. Additives included ground charcoal dust while the treatment and smell prevention started with anaerobic lactic-acid fermentation followed by vermicomposting.The generation of new Terra Preta (‘terra preta nova’) based on the safe treatment of human waste could be the basis for sustainable agriculture in the twenty-first century to produce food for billions of people, and could lead to attaining a number of major Millennium Development Goals at the same time.