The image one gets when they think "organic" is of a small farmer growing food without pesticides and cattle without antibiotics being grazed in open pastures. This is the idea behind organic farming, to grow food more naturally, more safely for the consumer and with less impact on the environment.
But organic or not, the United States must grow food on a massive scale, so Pollan raises the question in The Omnivore's Dilemma about whether or not the largest farms can still operate in an organic fashion. "Industrial Organic" might refer to large cattle operations, for example, that still pack cows in close proximity to each other, but do not use antibiotics. To grow crops on a large scale but still organically requires that they not use herbicides and pesticides, but also means the soil must be tilled more often, which uses more fuel and erodes the topsoil. So how organic is it?
"Organic" methods do, Pollan argues, still encourage agriculture and food production and processing to be healthier, safer and more environmentally friendly, but cannot change the overall nature of agriculture, which has to be industrial in scale. It also cannot prevent even organically grown food from being shipped hundreds (or thousands) of miles, which sort of defeats the purpose.