Redefining agricultural yields: From tonnes to people nourished per hectare

Background/Question/Methods

Increasing demand for animal products is a crucial factor driving global food security challenges in the coming decades.  It is also of importance to the global environment because the production of animal products requires more land than plant-based foods. In fact, livestock production is the single largest anthropogenic use of land.

 In this study, we consider how different systems of crop production and crop use are interwoven to actually feed people around the world.  Specifically, we map global patterns of crop production as well as crop allocation (for human consumed food, animal feed, biofuels, and other non-food products) to determine the amount of human-consumable calories produced across the world.  By comparing crop production (in terms of tonnes of crop per hectare) to actual food delivery (in terms of calories of human-consumable product per hectare), we illustrate where tremendous inefficiencies in the global food system exist today – and where opportunities to enhance food security exist by changing dietary preferences and biofuel policies.

Results/Conclusions

From the 41 crops analyzed in this study, 9.46 x 10¹⁵ calories available in plant form are produced by crops globally, of which 55% directly feed to humans. However, 36% of these produced calories go to animal feed, of which 89% is lost, such that only 4% of crop-produced calories are available by humans in the form of animal products. Another 9% of crop-produced calories are used for industrial uses and biofuels and so completely lost from the food system. Including both human-edible crop calories and feed-produced animal calories, only 5.57 x 10¹⁵ (59% of the total produced) calories are delivered to the world’s food system. Therefore, 41% of the calories available from global crop production are lost to the food system.

 Put another way, shifting the crops used for feed and other uses towards direct human food consumption could increase calories in the food system by 3.89 x10¹⁵ calories, from 5.57x10¹⁵ to 9.46 x10¹⁵ calories, or a ~70% increase.  A Quadrillion (1 x 10¹⁵) food calories is enough to feed just over 1 billion people a 2,700 calories per day diet for a year (which is 985,500 calories per year). Therefore, shifting the crop calories used for feed and other uses to direct human consumption could potentially feed an additional ~4 billion people.