This post produced a few reasonable criticisms, so I spent the better part of last night reading through studies and briefing papers on the organic-synthetic divide in agriculture. This paper by Rodale Institute, a pro-organic policy shop, makes a strong case for organics as a solution to global warming (the graph above comes from the paper). Here is an imporatant bit about using soil as a carbon sink:
During the 1990s, results from the Compost Utilization Trial (CUT) at Rodale Institutea 10-year study comparing the use of composts, manures and synthetic chemical fertilizershow that the use of composted manure with crop rotations in organic systems can result in carbon sequestration of up to 2,000 lbs/ac/year. By contrast, fields under standard tillage relying on chemical fertilizers lost almost 300 pounds of carbon per acre per year. Storingor sequesteringup to 2,000 lbs/ac/year of carbon means that more than 7,000 pounds of carbon dioxide are taken from the air and trapped in that field soil.
I seem to have dissed soil micro-organisims to readily. If you only read one paper on the conflict between increasing yields and sustainability, this 2002 nature article is on the money:
There is a general consensus that agriculture has the capability to meet the food needs of 810 billion people while substantially decreasing the proportion of the population who go hungry, but there is little consensus on how this can be achieved by sustainable means. Sustainability implies both high yields that can be maintained, even in the face of major shocks, and agricultural practices that have acceptable environmental impacts. The main environmental impacts of agriculture come from the conversion of natural ecosystems to agriculture, from agricultural nutrients that pollute aquatic and terrestrial habitats and groundwater, and from pesticides, especially bioaccumulating or persistent organic agricultural pollutants. Agricultural nutrients enter other ecosystems through leaching, volatilization and the waste streams of livestock and humans. Pesticides can also harm human health, as can pathogens, including antibiotic-resistant pathogens associated with certain animal production practices.
How can such costs be minimized at the same time that food production is increased? In one sense the answer is simple: crop and livestock production must increase without an increase in the negative environmental impacts associated with agriculture, which means large increases in the efficiency of nitrogen, phosphorus and water use, and integrated pest management that minimizes the need for toxic pesticides. In reality, achieving such a scenario represents one of the greatest scientific challenges facing humankind because of the trade-offs among competing economic and environmental goals, and inadequate knowledge of the key biological, biogeochemical and ecological processes.