It's a good point. The trick is in not letting 'Big Oil/AG' steamroll local farmers and herders, as is happening in some marginal lands across India. It might be a balance that impossible to hold.

http://www.treehugger.com/files/2008/07/jatropha-production-expands-indi...

'Wastelands' Not Always Unused
Furthermore, groups such as Navdanya have pointed out that many of the lands called “wastelands” by government actually are used by rural populations for grazing and other agricultural uses. Having no adequate land rights, and vital to these people’s survival can be put at risk in the rush to embrace Jatropha cultivation.

In a YesMagazine interview with Vandana Shiva, there is a helpful series of descriptions of how these 'Marginal Land Crops' will very likely yield more poverty and loss..

http://www.yesmagazine.org/article.asp?ID=570

There may be little rainfall in the deserts of Rajasthan, but the culture of Rajasthan evolved to manage that amount of rainfall, and they have developed miraculous technologies for harvesting and storing what rain they get. They have sophisticated underground storage systems and water-harvesting systems so that not a drop is wasted. These technologies still sustain cities like Jodhpur and Jaipur. They have enough drinking water because they've developed a conservation culture, and they grow crops that don't need much water. The moment you think the desert of Rajasthan should be growing rice paddy or cotton, you create scarcity.

Scarcity is not a result of uneven endowments—that is diversity. Scarcity is having a mismatch between a culture and nature's giving. Cultures have evolved cultural diversity to mimic the biological diversity of climates and ecosystems. It's when that relationship is disrupted that you get unsustainable population growth.

... Instead of leaving seeds in the hands of the peasants who co-evolve them in partnership with nature, seeds become a monopoly in the hands of five or six global corporations. Instead of water belonging to millions of local communities, water too is to be controlled by five or six global water giants. These are recipes that use economic systems to appropriate for the few the base of survival of the majority. The 80 percent who are dispossessed of the wealth of nature move into economic insecurity, because their livelihood as peasants, as fishermen, as farmers, as tribals, as forest dwellers, all depend on having the fisheries, the land, the forest, to make a living. When those rights are taken away, they become economic refugees—they become disposable people.

Bob