There are many ways in which organic and non-organic affect the environment other than land use (which is likely a marginal difference). Big agro, most associated with non-organic farming, does lots of bad things for the environment. Pesticides that are linked to decline of bee populations, pesticides that yield local imbalances in what animals/bugs are around to eat each other, synthetic fertilizers that thrash the land from being able to grow diverse crops into the future, chemical run offs into local water sources, exposure of workers to high concentrations of pesticides and their subsequent-related illnesses, GMO seeds spreading farther than the intended land mass mating with other species producing unknown effects (and lawsuits), etc.