As the need for food production in sub-tropical regions increases, so too will the need for additional plant nutrients in the form of fertilizers. Furthermore, after the sharp rise in nitrogen, phosphorus, potassium, and sulphur fertilizer prices midway through 2008, many people worried that fertilizer nutrient reserves were reaching critically low levels.

Despite these spikes in price, Paul Fixen, International Plant Nutrition Institute, Brookings, USA, and Adrian Johnston, International Plant Nutrition Institute, Saskatoon, Canada, describe world nitrogen, phosphorous, potassium and sulphur resources and reserves as “adequate for the foreseeable future”. In the case of potassium, for example, it is estimated that there is a potash reserve life of 235 years and reserve base of 500 years, while phosphate rock (PR) resources are thought to have a life of nearly 700 years.

Not all of these resources are easily extracted though, and as extraction becomes more difficult, prices will inevitably rise. As a result, there is an increasing incentive for fertiliser best management practices to be continuously refined in order to increase the efficiency of usage and therefore slow these increases in cost.

• World fertilizer nutrient reserves: a view to the future,
  P. E. Fixen, A. M. Johnston,
  J. Sci. Food Agric. 2012, 92, 1001–1005.
  DOI: 10.1002/jsfa.4532

The article is part of a Special Issue: 2nd International Symposium on Sustainable Agriculture in Sub-tropical Regions