>More productive in the sense that the same cultivated acreage now
>feeds more people than it used to. India's pop is up 145% since 1960.
but this isn't really the constraint is it? If there's one thing India's not short of, it's acreage. Also, you can't live on rice alone without getting pretty bad malnutrition; increases in grain crop yield alone don't change the number of people that can be fed by given acreage unless there is some reason to believe that supplies of milk, cooking fats, vegetables etc can be increased proportionately, either through increasing the marketable surplus or in some other way. I think it's one of the big muddles of the GM food debate that they've brought this kind of monovariable crop-yield talk back into agricultural economics, from whence it was expelled in the 1970s. Agricultural production is a programming problem and unless the rice crop yield was a constraining factor, changes in it don't change the solution. My guess would be that for sensible values of all the other variables, the rice crop yield would quite likely be a slack factor rather than a constraint.
>But could any humane regime ever dump modern
>techniques and go back to the old ways without
>forcing scores of millions to go hungry?
Surprisingly, potentially yes because once more it's a difficult programming problem and the bundle of food goods produced changes with the technology. In particular (and there are plenty of examples of this happening, back and forth, in Africa due to the old aid agency trick of providing unmaintainable agricultural equipment), if you give people a technology which improves the crop yield of grain, typically you will find that they end up at an equilibrium in which they eat more meat. So when you end up dumping modern techniques (because your tractor breaks) you grow less grain but eat more grain because you get rid of your beef cattle. Obviously, there has to be some high level sense in which technological progress in agriculture is good (so long as it doesn't poison us all), but the actual business of working out the impact of particular technologies is somewhere between tricky and impossible. Agri economics is everything that normal economics ought to be and it's no coincidence that some of the very best economists (Galbraith, Quiggin) started out in agri colleges.
best dd
btw I would be very careful about comparing urban/rural population statistics between India and China. Because of the way the Chinese data is compiled (I had the occasion to look this up the other day: http://www.iiasa.ac.at/Research/LUC/ChinaFood/argu/dataqua/dq_32.htm ), lots of the "urban" Chinese population are living in rural areas which are administratively part of the same province as neighbouring cities. The proportion of the population which is employed in agriculture is greater than the "rural" population figures often quoted and the whole statistical apparatus is a bit of a nightmare by BEA standards.
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