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Double-edge sword of P mining in South Africa

August 1, 2012

BusinessDay, a South African news magazine/site, recently carried an article with a fair amount of nuance regarding the various issues surrounding P sustainability.   (LINK)   It’s notable because it pertains to the situation in Africa, the nexus of so many of the key issues facing agricultural sustainability and the challenge of increasing agricultural yields in a way that is affordable to small farmers while preserving the natural environment and especially precious water supplies.  The Global P Network’s Dana Cordell is quoted, among others.  Here are some issues highlighted:

– P is needed for life and for high yield

– Morocco’s increasing dominance in the global P fertilizer markets

– P mines and fertilizer factories have high water demand and potential to contaminate water supplies

– P triggers algal blooms that deplete oxygen and generate algal toxins

– the availability of P in soils and fertilizers depends on soil pH

– superphosphate fertilizers are highly soluble and readily leach into streams, rivers, lakes, and oceans

– excess nutrient loads have compromised water quality in 30% of S Africa’s reservoirs

– S Africa’s population is growing at 2% per year but declining farm profitability and drought have reduced the number of farms in the country

– only 3% of S Africa’s landmass is truly fertile; 12% is suitable for growing rain-fed crops but agricultural water demands are intersecting with demands for water supply in cities

– topsoils are being lost, hence the need for fertilizer.  Organic farming practices are unlikely to be the answer.

All in all, lots of dimensions are discussed but the article does lack much discussion of potential solutions, such as P recycling from human wastes (ecological sanitation) and food wastes, on-farm P removal from runoff (algae connected to bioenergy?), or development of more P-efficient crops and cropping practices.  Of course, much also depends on capital (both financial and human) and there is much to be done there too.

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