Potassium deficiency in agricultural soils is a largely unrecognised but potentially significant threat to global food security if left unaddressed, finds new research involving researchers at UCL, University of Edinburgh and the UK Centre for Ecology & Hydrology.
The study, published in Nature Food, found that more potassium is being removed from agricultural soils than is being added, throughout many regions of the world. It also gives a series of recommendations for how to mitigate the issue.
Potassium is a vital nutrient for plant growth that helps with photosynthesis and respiration, the lack of which can inhibit plant growth and reduce crop yields. Farmers often spread potassium-rich fertilisers over their fields to replenish the depleted nutrient, but supply issues can inhibit its use, and there are lingering questions about its environmental impact.
The researchers report that globally, about 20% of agricultural soils face severe potassium deficiency, with particular regions likely to experience more critical shortages, including 44% of agricultural soils in South-East Asia, 39% in Latin America, 30% in Sub-Saharan Africa and 20% in East Asia, largely due to more intensive agricultural practices.
Potassium is produced by breaking down potassium-rich rocks. Plants cannot replenish it like they replenish nitrogen.
We do produce a lot of potassium-rich waste - sewage and food waste, for example - but most of it is also rich in other nutrients. So you can add a little of it, but adding too much of it can cause other problems (like eutrophication).
The other solution is to buy potassium fertiliser. A significant amount of this is produced in Russia, Kazakhstan and Ukraine, and I’m guessing its trade is being affected by the ongoing war.
Potash has been a huge chunk of the potassium supply, with most of it coming from Canada. But reports indicate we can’t keep up with the demand and it’s driving up prices.
https://link.springer.com/chapter/10.1007/978-94-007-0394-0_11
If it’s really a dire problem, it will make financial sense to start separating the potassium from organic waste and to divert food manufacturing byproducts like banana peels from animal feeds to fertilizer production.
Brine from desalination also contains potassium (among other important things). We’re going to have to start desalinating soon anyway.
https://www.nature.com/articles/s41545-022-00153-6
The deeper problem is that it makes ‘financial sense’ to let a lot of people starve.
I’ve read that plants with deeper roots can “bring up” nutrients from lower layers, which would help in the shorter term.
Longer term? No time to think about that…
This is possible, but plants with deep roots (shrubs, certain grasses and scrubs) usually take longer to grow.