Monday, February 14, 2011

What We Use Crop Land For

The above shows data from the UN Food and Agriculture Organization on the usage of cropland globally based on area used. This is expressed in billions of hectares (a hectare is 2.47 acres, and there are 259 ha to the square mile). So this, very roughly, expresses what our priorities are with our precious arable land (this is not completely accurate since not all cropland is equally valuable, so total area is only a rough indicator).  I have shown the top 10 crops explicitly, and then summed all the rest.  As you can see, the top ten crops use just shy of two-thirds of the area.

Also, nine of the top ten crops are grains or beans (and the exception, cotton, is not a food at all).  It's worth noting that all fruits and vegetables (even potatoes) are buried in "All Others".  Civilization largely runs on grains and beans.

Note the relatively modest increase in total crop area over the last fifty years - by about 30%.  In that timeframe, global population has more than doubled, from about 3b to over 6.75b, and per-capita nutrition has improved too.  The modest increase of crop area tells us that most of the increase in food production has come from improved yields (ie agricultural technology).

The next graph shows the same data as a line graph, so that it's easier to see changes in individual components:

You can see that the big growth stories are soybeans, corn (maize), and rapeseed.  That is, all things used for animal feed, and increasingly biofuels, rather than human food.  Wheat (primarily feeding humans as bread) is pretty static in total area.


Fixed Carbon said...

Stuart: To what degree is increased production limited by the availability of land that is appropriate for the crop, and by water? I wonder if wheat increases are largely dry land wheat, which relies upon precipitation rather than irrigation. I would guess that most potential for increased acreage is now in Africa, which will need improved governance and infrastructure for much increase.

Stuki said...

Reading this, I started thinking about where the increased output per area is coming from.

A very simplistic first approximation of agriculture, is that it is a means of fixing, or making available in a storable, transportable form, the energy radiated from the sun.

If all the additional crop yield is coming from sunshine stored in earlier eras, primarily as hydrocarbons, the efficiency gains will eventually reverse.

If it, on the other hand, comes from a better understanding of the biological processes involved, then that knowledge won't disappear even in a post oil world.

I know of no data for differentiating what part of the increase is due to which mechanism, however.

Also, assuming people farm the choicest locations first, leaving the less ideal ones for later, the actual efficiency gains realized on any given acre is probably even greater than what's arrived at by simply dividing output by farmed land.

rjs said...

it's clear from this that substantially more people could be fed with intensive gardening, rather than growing grain...

cabbage or potato yields could be 20 tons/acre, tomatoes only slightly less...