The Promise of GMOs: Conservation Tillage

This is a part of the series The Promise of GMOs. Do GMOs live up to the promises of the biotech industry? In the case of increasing conservation tillage, there is data to back up industry claims.

Reducing tillage

BIO’s claim here is that “Biotech is helping to feed the world by: [Allowing] farmers to reduce tilling farmland.”
Verdict: Promise met.
Tilling, the process of turning the soil, is one way to control weeds. Imagine going out in your yard and turning the sod over. It’d be a little while before weed seeds were able to germinate again, and farmers can use this time gap to get their crops started. Unfortunately, tilling isn’t that great at stopping weeds so farmers often (but not always) have to use other weed control methods anyway. Tilling also causes erosion and runoff, greenhouse gasses escape from the soil, and it takes a lot of energy and time to plow all those acres.
Anything that can help farmers become less reliant on tilling and move to conservation tillage (reduced- or no-till) is arguably a good thing. USDA and EPA researchers present evidence in Conservation Tillage, Herbicide Use, and Genetically Engineered Crops in the United States: The Case of Soybeans (paraphrased):

Soybeans genetically engineered with herbicide-tolerant (HT) traits have been the most widely and rapidly adopted GE crop in the United States, followed by HT cotton. USDA survey data shows that adoption of HT soybeans went from 17% in 1997 to 68% in 2001 to 93% in 2010. Plantings of HT cotton went from 10% of  in 1997 to 56% in 2001 to 78% in 2010. Adoption of HT corn was slower but reached 70% in 2010.
The use of conservation tillage systems increased throughout the 1980s and 1990s. Only 30% of soybean farmers used conservation tillage in 1996, but 63% did in 2006. Similarly, 33% of corn had conservation tillage in 1990, and 40% of corn acres did in 2006.
Anecdotal evidence indicates that HT crops (particularly HT soybeans) facilitates conservation tillage because the HT seeds makes weed control more effective and less costly. Researchers have studied the interaction of HT crops and conservation tillage systems. Most studies have found that conservation tillage and HT seeds are correlated, but it is difficult to determine whether HT adoption causes farmers to adopt conservation tillage practices, or whether adoption of conservation tillage practices causes farmers to adopt HT seeds.
In most cases we examined, adoption of HT crops facilitated use of conservation tillage and vice versa. This implies that by encouraging farmers to adopt conservation tillage, HT crop adoption indirectly benefits the environment by reducing soil losses and erosion, runoff, fuel use, and the carbon footprint of agriculture.

Similar data is presented in Conservation Tillage and Plant Biotechnology from the Conservation Technology Information Center.
Whether farmers are 1) choosing conservation tillage first, then finding that HT seeds make it easy, or 2) choosing HT seeds first, then finding that they can use conservation tillage – the end result of more acres in conservation tillage is the same. Corn still has some room to catch up but soybean has clearly seen an increase in conservation tillage, and this has either been encouraged by or aided by HT traits. For the claim of increased conservation tillage, the verdict is promise met.