Hidden hunger for potassium

We don’t get enough potassium and we don’t know that. Medical scientists sound the alarm, but their message hardly reaches agronomists, let alone growers. Thus, potassium fertilisation is not assessed from a human health perspective.

Intriguing in a sum: potassium as a health-promoting element. Agronomists have always assessed the need for potassium fertilisation from an agricultural point of view, but recently published studies place potassium application in a human health perspective. This potassium-for-human-health story started with medical scientists who reported about protective effects of this element. Their studies have been published in journals that are on the reading table of medical scientists and nutritionists. Their message didn’t reach agronomists, let alone farmers and fruit and vegetable growers. This shows that new medical insights are only slowly trickling through to agriculture and horticulture. Food companies respond much faster.

Western diet

The western diet is poor in potassium. In many countries both adults and children get far too little of this essential nutrient. The culprit is the choice of foods. Westernised diets are often rich in red meat, dairy products and processed foods – ingredients that contribute relatively little to the daily potassium requirement. Consumers would be wise to eat more fruits and vegetables, because they then get considerably more potassium. However, changing eating habits is not that easy.

Closing the gap

Farmers and fruit and vegetable growers can help close the gap between actual potassium intake and adequate intake level by at least following potassium fertilisation recommendations. In many regions of the world, however, the level of potassium fertilisation is structurally below the requirement of the crops. There are also reports about declining soil potassium levels in various regions. This threatens crop yields, but also human health. For the time being there are still many open questions, for example about the effect of a higher potassium rate on concentrations of other nutrients and on product quality parameters in general. It may be useful to split the potassium dose to be applied, or to apply this nutrient at a later stage in the growing season. The choice of potassium-accumulating cultivars may also be an option. Another aspect worth to investigate is the desired potassium:sodium ratio in fruits and vegetables. All in all, current potassium fertilisation practices need to be revised in the light of the need to increase the daily potassium intake of consumers with a westernised diet.

Prices

Additional potassium fertiliser costs should be reimbursed in some way, for instance via incentives or higher product prices. It may be advisable to involve stakeholders, such as governments, health insurers, supermarkets and consumer organisations. It is also conceivable to offer potassium-fortified fruits and vegetables through special sales channels, for instance health food stores.

This commentary is a summary of the original editorial in the Plant nutrition courier magazine.