A relatively small proportion of the food produced in the high-yielding regions of the world is actually delivered to the food system. Not just because of waste, which accounts for anything between 30 and 50% from post-harvest and manufacturing through to trade and consumption. Here, ‘delivering’ means how much food enters the food system in the form of edible items (even before it is wasted). A global study by Cassidy et al. (2013) calculated this proportion using energy units.
They expressed the productivity of all the crops in calories per ha per year (to be able to compare apples and pears) and mapped them per region. They assumed that an average person requires 2700 Kcal per year. With these two pieces of information they calculated the number of people that could the fed per ha of agricultural land on the basis of its current productivity. Note that 2700 Kcal is greater than the actual human needs, which fluctuate according to physical constitution between 1800 and 2100 Kcal per person per year. By considering 2700 Kcal they are already assuming a certain level of inherent value chain inefficiency, which gives more conservative estimates.
Potential vs. actual delivery
The map they developed shows that the most productive areas of the world can potentially feed 8 to 10 people per ha on the basis of current productivity, while the least productive regions can feed barely 3 to 4. But then they produced another map, that estimates how many people are effectively fed per ha of land. They developed this new map by computing the fraction of the total energy contained in a crop that is delivered to the food system in the form of edible energy.
For example, in the case of maize (or corn), only ca. 25% of the energy contained in the crop is delivered as edible energy, be it in the form of maize grain, meal or flour, or transformed into meat, milk, fructose, bier or candies, etc. This is because maize is used as raw material by different non-food industries, such as paint additives, plastics or biofuels. But also, because a large proportion of the harvest is used to feed livestock, which is inherently inefficient, as we all know.
Maize represents perhaps the most extreme case. But when we consider all cereals together (maize, wheat, rice, barley, oats, rye, sorghum, millet, etc.) yet 46% is used directly as food (raw or processed), 34% to fed livestock, and 20% used by the non-food industry.
Based on this information for the most important crops globally (not just cereals), Cassidy et al. built the above map, that shows the fraction of the total agricultural production delivered to the food system. In the most productive areas of the world, barely 20 to 30% of the food produced is delivered to the food system. In areas dominated by smallholder farming 80 to 100% of the food produced is delivered – i.e. consumed at home or traded locally. This does not mean though that food systems are necessarily more efficient, as post harvest losses can still be high in many of these regions.
These are – again – global estimates, based on a number of assumptions, and they may therefore be questioned. Yet they contribute further evidence to understand why increasing agricultural production in developed countries will continue to have a limited impact on achieving global food security (see also this previous post). Most of the non- or hardly renewable resources such as fossil fuels, rock phosphate, soils or (fossil) water are used in these regions to produce food that will never reach a human stomach.