Economic Effects of Sustainable Sanitation - SuSanA

2.2.4 Alternative counter measures against soil depletion
Sanitation: facts and interrelationships
As alternative to conventional agriculture, synthetic fertiliser application and linear nutrient
flows, circular nutrient management approaches can be applied (cf. Box 1). Following this
idea, the nutrients contained in human-, animal excreta and organic waste are utilised to
sustain soil fertility, rather than the ones contained in synthetic fertilisers. Globally, farmers
use approx. 160 million tons of synthetic fertilisers 12 each year, whereas in the same period 50
million tons of nutrients are discharged via conventional sanitation systems such as sewerage
networks and pit latrines, thereby affecting surrounding environments and communities
(Werner, 2004 cited in Rosemarin et al., 2008, p. 14). The Stockholm Environment Institute
(SEI, 2005) for instance, calculated that Sub-Saharan Africa could be self sufficient regarding
fertiliser application if circular nutrient management, as described above, would be
implemented (cited in Rosemarin et al. 2008, p. 21).
According to Joensson (2001, p. 436), nitrogen, phosphorus and potassium, contained in urine
and faeces can be recycled almost entirely to agriculture, ―except for some nitrogen-losses in
the form of ammonia‖ (also cf. Kirchmann and Pettersson, 1995). Additionally, the organic
matter present in the faecal component improves ―the humus content [...] of the soil [...] and
thus the water holding capacity and prevents erosion‖ (Esrey et al., 2001 cited in
Langergraber and Muellegger, 2004, p. 436). The nutrient content of excreta thereby varies
according to specific diets, revealing high nutrient contents being excreted e.g. in China and
South-Africa and comparably low values e.g. in Haiti and Uganda (cf. Figure 5). Values for
industrial countries like Sweden can well be compared to the concentrations estimated for
China (Joensson et al., 2004, p. 5).
Figure 5: Country specific nutrient concentration in excreta per person, per year (estimated values,
Joensson et al., 2004, p. 6)
12 Total weight of N, P2O5 and K2O
11