Illustrating China's journey to balance, circular, and secure potassium cycles in the last three decades

Abstract

Potassium (K), a critical mineral for the living system, is primarily used in the production of mineral K fertilizer to support national food security. However, the anthropogenic and natural cycle of K is less studied to reveal its corresponding nutrient availability and demand, soil balance and efficiency. This study, as one of the first attempts, aims to trace K flows and stocks along its cycle in China by applying substance flow analysis (SFA), K residues generation and circularity model during 1990–2020. It also seeks to explore the soil K balance at both national and provincial scales. The findings indicate that the cumulative demand for K was 628.8 million metric tons (Mt), of which 61.8 % was obtained from K residues. The soil K balance in China had shifted from deficit to excessive, with the soil being excessive by ∼12.5 % in 2020. However, the soil K balances in 31 provinces showed significant temporal and spatial variations, with ∼51.3 % of total cultivated area depleted in soil K in 2020. Our further analysis of China's strategies along such journey towards a balance, circular, and secure K cycles can help to inform other nations for reducing their dependence and competitions on K minerals.