Currently, most conventional agriculture depends on imported fertility, usually nitrogen fertilisers made from natural gas as well as phosphorous and potassium. This is unsustainable in many ways, most notably in the precarious nature and affordability of the UK’s natural gas supplies (see Figure1, below):
The provision of fertility is one of the principal limiting factors in UK agriculture. Well-designed farming systems are able to provide for their own fertility, through a combination of good waste management and return of fertility to the soil, as well as well-managed rotations of pasture and arable. Land under pasture will accumulate nitrogen, potassium and potash, and will deplete them if grazed year on year. The balance, in the Totnes and District land base, of arable and temporary grassland is ideal for the area to be able to provide for its fertility without the need for external inputs. This can be speeded up with the addition of clover to the temporary grass leys. The area at the moment has about 5 ha. of grass for every 2-3 ha. of arable land, which is the ideal proportion.
The ‘bringing home’ of food production will also require a reduced dependency on imported fertility. This will require a fresh look at how the area treats its human waste, as human waste contains, per person, nitrogen and phosphorous equivalent to that which agriculture requires to produce its food. Systems for safely and hygienically collecting and utilising human urine as a replacement for nitrogen fertilisers exist in other European countries, and systems for the safe composting of human waste have also been developed2.
- Parliamentary Office of Science and Technology, 2004 [↩]
- For one example of this from Sweden, see Schonning, C. (2001) Urine Diversion: hygienic risks and microbial guidelines. www.who.int/water_sanitation_health/wastewater/urineguidelines.pdf [↩]
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