Intensification of agriculture has greatly increased food availability
over recent decades. However, this has led to considerable
adverse environmental impacts, such as increases in
reactive nitrogen over-supply, eutrophication of land and water
bodies, greenhouse gas (GHG) emissions and biodiversity

It is commonly assumed that by 2050, agricultural
output will have to further increase by 50% to feed the projected
global population of over 9 billion7. This challenge is further
exacerbated by changing dietary patterns. It is, therefore, crucial
to curb the negative environmental impacts of agriculture, while
ensuring that the same quantity of food can be delivered. There
are many proposals for achieving this goal, such as further
increasing efficiency in production and resource use, or adopting
holistic approaches such as agroecology and organic production,
or reducing consumption of animal products and food
Organic agriculture is one concrete, but controversial, suggestion
for improving the sustainability of food systems. It refrains
from using synthetic fertilizers and pesticides, promotes crop
rotations and focuses on soil fertility and closed nutrient
cycles4, 12. The positive performance of organic agriculture when
measured against a range of environmental indicators has been
widely reported13–16. However, organic systems produce lower
yields17 and thus require larger land areas to produce the same
output as conventional production systems. In consequence,
environmental benefits of organic agriculture are less pronounced
or even absent if measured per unit of product than per unit of
area14, 18. Furthermore, abandoning synthetic N-fertilizers could
lead to nutrient undersupply, even with increased legume cropping19.
As a consequence, the ability of organic agriculture to feed
the world sustainably has been challenged19, 20. Some authors
contribute to the discussion on lower yields in organic agriculture
by considering nutrient availability, but none of these provide a
robust analysis of nutrient availability in organic production
systems19–21. In addition, these studies do not pursue a detailed
food systems approach, and do not address the role that animal
feeding regimes, consumption trends and food wastage (i.e. food
loss and waste) may play—all of which represent factors for
strategies that could substantially reduce land demand, while
alleviating environmental impacts and contributing to global food
availability2, 1