ABSTRACT
During the last few decades, the growing threats such as depletion of soil nitrogen, phosphorus and organic matter, eutrophication of rivers, competition for land between farmers and other interests (Blum, 2013), loss of soil fertility due to erosion and overexploitation and the challenge of establishing sustainable sanitation call for alternative approaches in sanitation and agriculture. The productive use of excreta from UDDTs can bring many economic and social benefits and contribute to an improvement in the soil quality by substituting or complementing chemical fertilizers. The recycling of nutrients and organic matter from excreta to the soil is becoming extremely important, given the current rate of loss in soil organic carbon stocks (FAO, 2015), combined with the depletion of non-renewable sources of nitrogen and phosphorus fertilizers (Dawson and Hilton, 2011) and the uneven distribution of potassium resources in nature (Ciari et al., 2015). The application of only chemical fertilizers to the soil has proven to be unsustainable, especially for countries that face financial limitations and ever increasing prices of the fertilizers. Long term experiments (Boincean et al., 2014) have shown that the application of increased amounts of chemical fertilizers leads to rapid decomposition of humus and even decreased yields (Mulvaney et al., 2009). Supplementation with organic matter is important for maintaining soil fertility and increasing soil resistance to erosion (Lal, 2002).
