Fig. 1.

Expansion of P-intensive soy agriculture in Mato Grosso, Brazil has led to soil P storage, a legacy that may lower future P fertilizer requirements (1). However, agricultural P demand and efficiency may depend as much on climatic variability and socioeconomic drivers as on soil biogeochemical conditions. Ideally, P inputs mirror crop outputs, creating high PUE, which reduces pressure on finite P fertilizer reserves and minimizes P loss to the surrounding environment. However, high PUE is rare because suboptimal climate variation and other disturbances typically suppress crop yields below their maximum potential. Society’s overall P use efficiency is also low for reasons that range from P-intensive dietary choices to minimal P recycling. Reducing P-driven environmental damages and world fertilizer demand, while simultaneously meeting food security challenges, will require management and policy changes that increase PUE along the entire path from crop growth to human consumption. Photo credit: Chris Neill.