Potassium depletion in agricultural soils threatens food security

The threat of potassium depletion in agricultural soils, a crucial nutrient for plant growth, is emerging as a significant concern for global food security. This is the conclusion of new research led by University College London (UCL).

The study reveals a critical imbalance that is happening on a global scale. More potassium is being removed from soils than replenished, posing a risk to crop yields and, consequently, food supplies.

Lack of potassium in soil is significant threat

Potassium aids in essential plant functions such as photosynthesis and respiration. Its absence can severely limit growth, affecting food production. 

Traditionally, farmers combat potassium depletion with potassium-rich fertilizers. However, challenges like supply constraints and environmental concerns underscore the complexity of this solution.

The researchers identified an alarming global trend of potassium deficiency. They found that about 20% of agricultural soils worldwide are severely lacking this nutrient.

The situation is particularly dire in regions with intensive farming practices, including 44% of soils in South-East Asia, 39% in Latin America, 30% in Sub-Saharan Africa, and 20% in East Asia.

Professor Mark Maslin (UCL Geography), a co-author of the study, emphasized the critical nature of this issue. 

“Potassium is critical to sustaining the crop yields that keep the world fed, and its depletion poses a significant threat to the food security of millions of people around the world,” said Maslin. “This is an overlooked issue that needs to be addressed with a range of actions as the world population continues to grow.”

Key source of potassium soil fertilizer

The study highlights the market’s volatility for potash, a key source of potassium fertilizer. Potash is dominated by a few countries, leading to price surges and supply disruptions. 

Notably, the situation was exacerbated by geopolitical tensions, such as the Russian invasion of Ukraine. This led to sanctions affecting potash exports from Russia and Belarus, significant global suppliers.

“The volatility of potash prices has major implications across the global food system. Access to potassium is vital for farmers to maintain their crop yields, but the recent high cost of potash makes it more difficult for the most vulnerable to obtain,” said co-author Peter Alexander, a geoscientist at the University of Edinburgh.

Mitigating risks to food security 

To combat these challenges and mitigate the risk to food security, the researchers propose several recommendations. They are calling for national capabilities to manage price fluctuations, research on soil potassium levels, and the evaluation of potash mining’s environmental impact.

In addition, the team recommends the development of a global circular potassium economy. Furthermore, the experts call for increased intergovernmental cooperation to coordinate policies on potassium management.

“The environmental impact of potash mining and use in agriculture is something that needs greater scrutiny. There’s much that we still don’t understand about the effects that artificial potassium enrichment has on nearby ecosystems,” said study lead author Will Brownlie of the UK Center for Ecology & Hydrology.

“By wisely handling nutrients like nitrogen, phosphorus, and potassium together, we can reap multiple benefits, prevent pollution, boost crop yields, and minimize nutrient loss. It’s about coordinating our approach for better farming outcomes.”

The study is published in the journal Nature Food.

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