GE crops were introduced in 1996 and have been widely adopted by producers. GE crops include herbicide-tolerant (HT) crops and insect-resistant (Bt) crops. HT crops were developed to survive specific herbicides, particularly glyphosate, that previously would have destroyed the crop along with the targeted weeds. Insect-resistant crops contain the gene from the soil bacterium Bt (Bacillus thuringiensis) that produces a protein toxic to specific insects, protecting the plant from insect damage. Based on USDA survey data, GE crops accounted for 94 percent of U.S. soybean acreage, 90 percent of U.S. cotton acreage, and 88 percent of U.S. corn acreage in 2011.

According to ERS research, U.S. farmers are realizing economic benefits from adopting GE crops, including lower pesticide costs, savings in management time, and, in many cases, higher yields through reduced losses to pests.   And to the extent that GE crops lower the cost of production and increase yields, they put downward pressure on crop prices, which, over time, forces out the least efficient producers, encouraging further consolidation of farming resources and concentration of production.

The impacts of GE crops vary with the crop, technology, pest-infestation levels, and other factors.  Overall pesticide use and/or pesticide toxicity is lower for adopters of GE crops, and the adoption of herbicide-tolerant crops may also indirectly benefit the environment by encouraging the adoption of less intensive tillage (how farmers prepare their soil for seeding and weed/pest control) practices. However, weed resistance to glyphosate has become a problem in some areas, particularly the South, and some contend that GE crops are not safe to eat (some European countries ban importation of GE commodities). Farmers marketing non-GE varieties also cite potential risks of “gene flow” from nearby fields planted to GE crops.

Farmers have a number of tillage options, including “conventional” or plow tillage and several types of “conservation” tillage—such as mulch till, ridge till, and no-till—that leave at least 30 percent of the soil covered by crop residue. Conservation tillage—particularly no-till—decreases soil erosion, increases water retention, reduces chemical runoff, and can shrink the carbon footprint of agriculture by lowering onfarm energy use and sequestering carbon within the soil.

Adoption of conservation tillage and a corresponding decline in conventional tillage has been stimulated by the prospects of higher economic returns and by public policies and programs promoting reduced tillage for its environmental benefits. As a result, conservation tillage has increased since 1989. Since this tillage option uses fewer resources to ready the land for planting, when coupled with herbicide-tolerant crops, the benefits of GE crops and conservation tillage reinforce each other. However, since conservation tillage does not eliminate pests, when coupled with non-GE crops, pesticide usage and management requirements may increase while potentially lowering crop yields.

Despite the benefits arising from the use of GE crops and conservation tillage, the concentration of production on larger crop farms still generates concerns about food safety, environmental degradation, and the structure of agriculture. This has created a demand for commodities produced using alternative production methods, such as organic farming.