Nature’s Phosphate Cycle

Nature moves in cycles. The most common cycles are the carbon, nitrogen and phosphate cycle, but there are others. Plants take their nutrients from the soil and air. Biomass is formed as the plant grows and matures. The plant die or are eaten by animal. The animals defecate and ultimately die. In each case the minerals that were taken up by the plant ultimately return to the soil to be taken up by subsequent plants, and the cycle continues.

Since we depend on nature for our sustenance, we do well to understand that cycle and nurture it. But industrialized agriculture does not do that. It has found very effective ways of circumventing the natural cycle. The result has been phenomenal crop production. But are these results sustainable?

 
For thousands of years, the Chinese and Indian civilizations have mimicked the natural cycle. Each peasant farm was more or less self-contained so that all biological material coming from the farm ultimately was returned to the soil of that farm. Most notably, human waste was returned to agricultural fields, often after careful composting. Using these techniques, they were able to maintain the fertility of their fields for those thousands of years.

In recent years, agriculture in those countries has also industrialized. Here too, this has resulted in phenomenal yield increases.

 
But industrialized agriculture, in significant respects, ignores the natural cycle. Within an industrialized system, a field is tested for available plant nutrients. The interest here is primarily in the macro-nutrients N, P, K, and S. Fertilizer is then blended and applied at the rate that will optimize plant growth. The questions: where does the fertilizer come from, and is the supply reliable, are not asked.

But if we are to build a sustainable, stable society, these questions need to be asked. In Canada, phosphate is mined near Kapuskasing in Ontario and near Radium in BC. But Canada, in spite of its vast geological formations, has not discovered any really good phosphate deposits, and we do not produce world class phosphate. The most readily available phosphate rock has already been utilized, and the phosphate we are going after now requires more energy to extract and is of a lower quality.

Phosphate is essential to crop growth. Unlike petroleum energy, which can, in certain circumstances be replaced with other forms of energy, there are no substitutes for phosphate. There is only one reasonable response to looming phosphate shortages. We need to use the phosphate currently within the food production system more efficiently. This means the more efficient return of livestock manure to growing crops, but also the recycling of human waste, which is rich in phosphate, to agricultural fields.

Currently, there is little incentive to do any of the necessary recycling. Just as a carbon tax is needed if we are all to use energy more efficiently, a resource use tax is needed to get us to change our phosphate use habits before the shortage of phosphate has a catastrophic effect on our food supply.

Eric Rempel