Sustainability is the priority

The popular and scientific media now have their eyes on fertilizers and the reserves and the feedstocks required to produce them. This was prompted by the eruption in early 2008 of the worldwide food crisis that paralleled the spike in commodity prices and new demands on the available crop areas to supply biofuels. Many commentators recognised the role of fertilizers in producing not only food, but fibres, feed and now fuel. In particular, production of several of the leading fertilizer nutrients involved harnessing resources that were non-renewable, and involving production processes that had an environmental impact via emissions and the use and disposal of by-products. Of further concern was the limited efficiency of plants’ uptake of those nutrients.
Particular concern began to focus on phosphorus. The Scientific American published a feature entitled Phosphorus: A Looming Crisis and introduced the concept of “Peak Phosphate,” on a par with the peak oil model. Other commentators followed in a similar vein, raising doubts on the long-term sustainability of phosphate rock production and suggesting that future supplies of phosphate fertilizers may be in jeopardy. Market volatility would ensue, and global food security would face a further threat.
The International Plant Nutrition Institute (IPNI) was prompted by these media articles to undertake a review of world nutrient reserves, drawing further on the data accumulated by the US Geological Service (USGS). In 2008, the USGS estimated that the present known economic reserves of phosphate rock total 15.42 billion tonnes worldwide, giving a reserve life of 93 years at current mining levels of around 160 million t/a. The reserve base is estimated at 46.75 billion tonnes, covering economic, marginally economic and some currently sub-economic resources. This reserve base has an estimated life of 291 years.
IPNI commented that while the USGS estimates of reserves and resources are currently the best available, they lack certainty and suffer from a shortage of reliable data. “Reserve information is at best a general approximation,” said Terry Roberts, IPNI President (Sustainability of World Nutrient Resources, Dr. Terry Roberts. Paper presented at AFA International Fertilizers Forum. [February 2010].) Based on other interpretations of the phosphate reserve and resource, the life span is far longer – up to 600-700 years.
The Peak Phosphorus theory nevertheless exercises the minds of many people in the fertilizer industry. However challengeable the notions, any factor that persuades industry executives to take a longer-term strategic approach is to be welcomed. The issue was much debated at British Sulphur Events’ Phosphates 2010 conference in Brussels, as reviewed elsewhere in this issue. Terry Roberts expresses a consensus view when he concluded that rock phosphate is a non-renewable resource that should be used as efficiently as possible. “Clearly the world is not on the verge of running out of raw materials for P fertilizer production, but the longevity of rock phosphate reserves must be scrutinised with an awareness of the reliability of the available data,” he said.
The sustainability of production of nitrogen fertilizers must also be scrutinised. This is because of the natural gas feedstock that is harnessed to produce some three-quarters of the world’s output of ammonia. In effect, reserves for nitrogen fertilizers are best approximated by reserves of natural gas. At first sight, the gas scenario is even more alarming than that for phosphates: current global gas consumption is around 3.2 tcm/year. With gas reserves currently estimated at 175 tcm, the world has sufficient gas to last around 55 years. However, as with coal in earlier years and more recently oil, natural gas exploration has been vigorous and new resources have been discovered to boost the overall forecast. The life forecast may thus be extended.
Of the other primary nutrients, potash reserves appear to be sufficient to sustain world production for at least 235 years. The USGS data on the global potash resource is not subject to the same uncertainty as phosphate rock. The reserve base has a life expectancy of over 500 years globally, with some geologists suggesting that Saskatchewan’s reserve base could extend to a full millennium. USGS has recently estimated world resources of proven, probable and inferred resources of potash at 250 billion tonnes, sufficient to last thousands of years.
The primary sulphur for agricultural use and as a raw material in the phosphate industry is the energy sector. Sulphur is a by-product, with production to a large extent involuntary, extracted from natural gas and crude oil. At current production levels, the sulphur extracted from these sources has an estimated life of 70 years. There are many additional sources of sulphur, which have not been tapped in full. Examples include extraction for coal and oil shale and an almost limitless source of S in gypsum. A global sulphur shortage is not predicted in the foreseeable future.
These factors suggest a less doom-laden scenario than some pundits and media would allow. However, the central fact remains that fertilizers are based on non-renewable resources. The industry should further endeavour to curb escalating costs of nutrient production in order to keep the final product affordable to the farmer. As Luc Maene, Director General of IFA observes, it is critical that all nutrients be used responsibly, via diligent stewardship and best management practices. IPNI and IFA are liaising with other organisations to promote and implement the 4Rs – right source, right rate, right time and right place. In this way, sustainability is set to become a part of the fertilizer industry’s DNA.