Food + feed - 3 Gt cereals/year by 2050 estimated in 2009 - based on 3000 cal/day

Did 2.5 Gt in 2019

Competing land use for biofuels

But calorie demand per day is much higher (8000/day) in developed countries

That suggests a need to double (5 Gt) or more based on projected growth - so range is 20-175% growth by 2050

Not all places get high yield - North America and Europe for maize, China for rice.

Water use is not coordinated internationally - UK is a water importer, Australia water exporter

Phosphorus necessary for ATP

Phosphate is being removed from the ag system (eg because we don’t recycle sewage) and we’re running out; it’s being added too quickly to the land and converting to plant-unusable forms

China has 135% export tax on phosphate rock; 72% of reserves are in Morocco; maybe 100 years left

Two kinds of photosynthesis C3 and C4. Maize is C4, rice is C3. C4 generates more biomass, is more efficient at using light, nitrogen, water.

Making rice C4 would deliver the extra calories Asia needs (?)

Needs 10 gene changes; most complex to date is 2 for golden rice. But at least we know what genes need changing.

Synthetic biology is improving ability to do this