‘What if soil runs out?’
Professor John Crawford
12.1 Land Types, Yields, and Erosion
It has been suggested several times in this book that soil is a hub for water, food, energy, climate, and health. According to John Crawford, a rough calculation of current rates of soil degradation suggests we have about 60 years of good soil left. Some 40% of soil used for agriculture around the world is viewed as either degraded or seriously degraded, meaning that 70% of the best type of soil is gone. We are in fact borrowing from the future in order to get cheap food, cheap water, and cheap energy.
Various farming methods strip the soil of carbon and make it less robust and weaker in nutrients; soil is being lost quickly, even the well-maintained farming land in Europe.
Agriculture accounts for 70% of fresh water use; but this water is wasted if it goes through degraded soil and past the root system.
Several key issues, obviously inter-related, are faced:
- Loss of soil productivity: in the present conditions, soil will produce 30% less food in the next 20 to 40 years. Wheat output in China should face a 40% reduction by 2030.
- Soil is being eroded at a rate that is 10 to 40 times faster than it can be sustainably replaced, in particular because of loss of nutrients.
- Biofuels, fracking, and coal seam gas are threats to land and water.
- Water may be a source of conflict in sensitive parts of the world like the Middle East. It is most serious in China, ...