Genetically modified (GM) crops are plants whose genetic material has been altered to introduce beneficial traits, such as pest resistance or herbicide tolerance. The global adoption of these crops, primarily since the mid-1990s, has brought about significant shifts in agricultural practices. These technological changes offer a range of environmental benefits that extend across farm management, soil health, and global conservation efforts.
Reducing the Need for Applied Chemicals
One of the most direct environmental advantages of GM crops stems from the reduction in insecticide use, particularly through the adoption of insect-resistant crops, often referred to as Bt crops. These plants are engineered to produce proteins from the bacterium Bacillus thuringiensis (Bt), which is toxic to certain insect pests, such as the European corn borer and cotton bollworm. By having the protective trait within the plant itself, farmers can significantly decrease the frequency and volume of broad-spectrum insecticide sprays on their fields.
Between 1996 and 2018, the global adoption of GM crops resulted in a reduction of pesticide spraying by 776 million kilograms. This decrease in chemical application is measured by indicators like the Environmental Impact Quotient (EIQ), which saw an overall improvement of 19%. For example, GM insect-resistant cotton alone led to a net savings of 331 million kilograms of insecticide over the same period.
Herbicide-tolerant (HT) crops influence chemical use by enabling the effective management of weeds with specific herbicides. These HT crops are resistant to broad-spectrum herbicides like glyphosate, allowing farmers to control weeds without damaging the crop. While this practice may sometimes increase the total volume of herbicide active ingredient used, it often replaces the need for multiple applications of older, more persistent, or more environmentally toxic chemicals. The overall environmental impact, as measured by the EIQ for herbicides, has shown improvement because the newer herbicides used with HT crops often have a better environmental profile.
Improving Soil Structure and Water Retention
The widespread adoption of HT crops has fundamentally changed how farmers approach weed control, which in turn has fostered the switch to conservation tillage practices, most notably “no-till” farming. Before HT crops, weeds were primarily controlled by mechanical tilling, or plowing, which is highly disruptive to the soil structure. The effectiveness of HT crops in managing weeds chemically removes the necessity of this mechanical soil disturbance.
No-till farming, facilitated by HT crops, involves leaving the soil largely undisturbed from harvest to planting. When the soil is not turned over, the topsoil remains anchored, dramatically reducing soil erosion caused by wind and water runoff. This practice preserves the soil’s natural structure, creating more resilient soil that is less prone to degradation.
No-till systems lead to a significant increase in the amount of organic matter retained in the soil. The crop residues left on the surface act as a mulch, slowing water evaporation and improving water infiltration. The soil’s ability to store moisture means that these farming systems require less supplemental irrigation, conserving water resources. The improved organic matter and reduced disturbance also foster a healthier microbial community, which is important for nutrient cycling and overall soil fertility.
Supporting Biodiversity and Climate Goals
GM crops contribute to biodiversity through “land sparing,” a mechanism resulting from their higher productivity. By providing better pest control and weed management, GM crops lead to increased yields compared to conventional varieties. This increased output means farmers can produce more food on the same amount of land, reducing the pressure to convert natural habitats, such as forests and grasslands, into new agricultural fields.
Since 1996, the enhanced productivity of GM crops has saved an estimated 183 million hectares of land from being converted to farmland globally. This preservation of natural ecosystems protects the diverse species that inhabit those areas, supporting macro-level biodiversity. The increased efficiency allows global food demand to be met without requiring further extensive agricultural expansion.
GM crop adoption also supports climate goals by reducing agricultural greenhouse gas (GHG) emissions. The shift toward no-till farming, enabled by HT crops, significantly reduces the number of times heavy machinery must pass over the field, leading to decreased fuel consumption. In 2018 alone, these practices led to a reduction in fuel use equivalent to removing 15.27 million cars from the roads for one year. Additionally, leaving the soil undisturbed through no-till practices allows the soil to sequester carbon more effectively, helping to mitigate the buildup of GHGs in the atmosphere. Wider adoption of existing GM crops in regions like the European Union could reduce agricultural GHG emissions by an estimated 7.5%.