fiplibs
As far as alternatives go, an instructive example is post-USSR Cuba. Before 1991 they were a satellite-state which sold sugar at above market prices to the USSR and in exchange received oil and farm machinery. After the collapse they had to, essentially overnight, switch over to subsistence farming. They use low-input techniques by necessity due to the high price of fossil fuels.
In almost every Cuban town there is a microbiologist who will examine the soil from your plot and recommend biological or chemical amendments. Open spaces in Havana are populated with [collectively-run] urban gardens. They're the first country applying permaculture techniques on a large scale.
Permaculture can actually be more productive per acre than industrial agriculture, but it requires more (and more educated) labor to do so. http://en.wikipedia.org/wiki/Permaculture
One of the best predictors of a woman's fertility rate is their level of education. Higher education leads to fewer children on average. This is largely independent of the fertility of their parents.
Also, if you look at the third world, there are actually some good economic arguments for having more children, related to infant mortality. Your children are your 'Social Security', so you want to ensure that some survive. Paradoxically, reducing infant mortality can actually reduce fertility. http://video.google.com/videoplay?docid=-5192204318056302269