international fertilizer correspondent No 2

Potash tells a different tale

Farmers favour nitrogen and can you blame them? Crops respond quickly, growing taller, greener and more lush. How, they think, can extra nitrogen be too much of a good thing? From the ‘70s to the early ‘90s, many farmers fed their fields with more nitrogen than was removed in harvested crops. And, in the last few years, the upward trend in the use of nitrogen fertilizer has resumed. Phosphate use reveals a similar story but potash tells a different tale.

Photo: K+S

On a global scale, far less potash is applied by farmers than is removed by their harvested crops. Even the recent, slight increase in potash consumption is far too low to compensate for steadily increasing K removal. In view of the growing demand for more and better food, it is difficult to imagine that the goal to nearly double cereal production by 2020 can be achieved while the gap in the K balance is still widening.

Global trends are interesting and may be informative, but nutrient need and, more particularly, fertilizer use, depend on factors that have more relevance at a regional level. Whether farmers apply fertilizers or not, and whether they have the necessary knowledge, money, credit or, indeed, whether fertilizers are locally available, depends as much upon political and economic history as in the inherent fertility of their soils or the nutrient demands of their crops. To take three examples:

Eastern Europe and the CIS

Economic reforms, and the disintegration of fertilizer distribution channels, have led to plummeting fertilizer use with potash falling further than N or P. The economic loss of lower crop yields has been compounded by lower quality and higher disease and pest incidence. The drop in cereal production has also reduced the availability of feed, leading to a substantial reduction in livestock numbers and the availability of manure as an alternative source of soil nutrients.

Asia

Although Asia's crop production, as calculated by K removal, is more than half total production worldwide, it consumes little more than a quarter of global potash. And the gap between K removal and supply is steadily increasing. This is not surprising as Asia has no substantial potash deposits and almost all potash must be imported. Furthermore, if decontrol of pricing means that fertilizers containing potash become more expensive, farmers naturally turn to cheaper options, even if these are less effective and thus more costly in the long term. The discreet action of K, (the effect of its loss is not immediately obvious) has lulled farmers into a false sense of security and it is only as the green revolution has slowed to a halt that the risks of unbalanced nutrition have become more widely apparent.

Western Europe

Environmental and economic concerns ended the steady increase in fertilizer use seen throughout the ‘80s. With the advent of what has come to be called ‘precision farming’, fertilizer application should, in future, match more closely the nutrient demands of the crop. Furthermore, the financial penalties that have been introduced for excessive use of nitrogen fertilizer, should ensure that more attention is paid in future to balanced fertilization that includes potash.

Practising unbalanced fertilization creates a vicious spiral. Farmers, disillusioned by poor yields and income, leave the nutrition of their next crop to the supplying power of the soil. But with loss in fertility, the soil cannot sustain crop production and the farmer spirals further into poverty.