Experts discuss the conservation impact of no-till, the uncertainties around its climate change mitigation value, and the need to integrate the practice within broader soil health management systems to realize its full benefits.
The U.S. Nature4Climate coalition recently convened a panel of experts to discuss the benefits of implementing no-till on farms in the United States, as well as the uncertainties around the practice’s climate mitigation benefits. Our panel included the following experts, providing a diverse range of viewpoints on the topic:
- Lesley Atwood – Agriculture & Climate Scientist – The Nature Conservancy
- Barry Fisher – President, Fisher Soil Health and Soil Health Farmer Innovator; Former Central Team Leader & Soil Health Specialist – USDA Natural Resources Conservation Service
- Jocelyn Lavallee – Agricultural Soil Carbon Scientist – Environmental Defense Fund
- Bianca Moebius-Clune – Climate Initiative Director – American Farmland Trust
- Tim Searchinger – Senior Fellow and Technical Director, Food Program – World Resources Institute
WHAT IS NO-TILL AGRICULTURE?
No-till, according to the USDA-NRCS no-till conservation practice standard (CPS 329), entails “limiting soil disturbance to manage […] plant residue on the soil surface year around.” According to the USDA Natural Resources Conservation Service,“No-till protects the soil from excessive erosion, reduces soil aeration from tillage, allows organic matter to accumulate and improves the overall health of the soil. Switching can also help you reduce input costs and, thus, boost your bottom-line profits. It is part of an integrated effort to conserve the nation’s natural resources.”
No-Till Should Be Viewed as a Component of a Broader System of Conservation Agricultural Practices
Some of our panelists noted that no-till should not be viewed as a stand-alone agricultural practice – rather, it should be implemented with a suite of other conservation agriculture strategies. In the words of Barry Fisher:,
“No-till is a foundational practice that's a part of conservation agriculture, sustainable agriculture, regenerative agriculture or soil health management systems. However, describing no-till narrowly, as a stand alone practice with a singular purpose or consistent methods is an incomplete definition as well.There are many ways to undertake the no-till practice successfully, unsuccessfully, or intentionally for certain benefits, and not necessarily intentionally for other benefits. No farmer can just no-till. They must adapt nutrient, and pest management, as well as other technologies and practices specifically for no-till. How those practices are integrated into the system is always going to be the key to the true outcome from the system.”
According to Bianca Moebius-Clune, these practices include conservation crop rotation, cover crops, prescribed grazing where feasible, and potentially adding carbon-based materials such as compost or biochar, and integrating woody perennials for more diverse production systems, such as silvopasture and agroforestry.
Moebius-Clune further suggested that agricultural systems must combine several of these practices to achieve key soil health management principles that protect the soil (minimized disturbance and maximized soil cover) and feed soil organisms (maximized biodiversity and presence of living roots) in order to realize significant benefits:
“I think that for climate, the benefits are significant, because when we build fully functional systems that get that carbon deep into the soil and protect it, we're going to sequester a lot of carbon. And we get all of the resilience benefits of improved aeration, water cycling, nutrient cycling, biological activity – leading to higher and more consistent yields from decreased drought and flooding impact. And when we pair researchers with excellent producers who really know what they're doing with no-till, and who are combining no-till with all of the other practices that need to be part of that suite, we will find that no-till in that context will maintain and increase carbon.
Lesley Atwood reinforced this point, reminding us of a critical basic fact – that plants are needed to actually increase soil carbon:
“No-tillage is a way to protect the carbon that is in the soil. To add carbon, we need plants. Plants are responsible for grabbing atmospheric carbon dioxide and moving it into the soil system through the process of photosynthesis.”
BENEFITS & UNCERTAINTIES
No-Till Offers Several Advantages for Farmers & The Environment
There was general agreement on the panel that the no-till practice provides a number of important benefits to both farmers and the environment. As noted by Lesley Atwood:
“There are a lot of non-climate benefits, and it really comes down to the increases in soil organic matter in the topsoil that accompany no-tillage. Benefits like improved water infiltration, increased water retention, increased nutrient cycling, increased soil biodiversity, reduced soil erosion. Reduced soil erosion is really one of the main reasons no-tillage was conceived in the first place. It can also stabilize yields, especially in drier years.”
Barry Fisher added that farmers’ nutrient management practices should also be adjusted when implementing a no-till system.
“To be more profitable with no-till, you have to be able to adapt your nutrient management, and the beauty is once you reduce erosion and master the skills of managing biological nutrient cycles, you should be able to significantly reduce those nutrient inputs, particularly phosphorus.”
However, Tim Searchinger cautioned about nitrogen-related concerns during the transition:
“[T]here has been a fair amount of evidence that you get an increase in nitrous oxide emissions in the first few years – maybe 5 years – of no-till. There’s a lot of uncertainty about this, but I think that’s the predominance of the estimate. So, if a farmer plows up their no-till within five years, you may lose the soil carbon gain, but end up with an increase in nitrous oxide.”
Bianca Moebius-Clune agreed with this concern for transitioning degraded soils. She noted that farmers would need to adjust nitrogen inputs to excellently adapt to that no-till system, managed with cover crops and good rotations that will create better aggregation, aeration, water cycling, and nutrient cycling. “When we manage that physical soil functioning and inputs, we should be able to reduce nitrous oxide emissions effectively.”
Barry Fisher noted that technical assistance and high quality technical training for farmers and their service providers would be critical in helping them be successful in adapting, and therefore maintaining their new system. Support and facilitation of local no-till or soil health farmer networks and roundtables will also provide important technical support for adoption of these systems.
There Is Still Significant Uncertainty About Climate Mitigation Benefits of No-Till
Some panelists pointed out that there are still significant uncertainties in the climate mitigation impacts of no-till due to significant gaps in the scientific research around the practice. According to Tim Searchinger:
“In terms of soil carbon sequestration, I think the issue is a lot more uncertain at this point. I think you do have to kind of segregate out the effect of no-till from some of these other practices. The real debate on no-till was whether, when you measure carbon at depth, you're actually getting an increase in soil carbon, and there's wildly different literature on that subject.”
Because most U.S. no-till farmers plow up their lands every few years, Searchinger cautioned, net climate benefits will depend not only on resolving these uncertainties but also on guarantees that farmers maintain their no-till.
Jocelyn Lavallee reinforced this point, noting that the existing data makes it difficult to quantify the carbon sequestration benefits of no-till due to a lack of measurements at depth and in the context of systems as actually practiced on real farms:
“We know that a lot of the other benefits of no-till are there – it's just that the effects in terms of climate mitigation haven't been properly quantified across enough different contexts and in enough different systems yet…It is very important to design experiments well and work with real farms to make sure we are measuring carbon at depth to capture that potential relocation and make sure we really understand what is happening with the carbon balance, as well as the full net GHG balance.”
FILLING RESEARCH GAPS
Our panelists suggested a number of actions that can be taken to help fill gaps in the research around the climate change mitigation benefits of no-till agriculture.
Researching Agricultural Systems, Rather Than Focusing on Individual Practices
Several panelists made the point that researchers should view no-till as part of agricultural systems, not as an individual practice. In Jocelyn Lavallee’s words, “We have to look at the whole system – it’s a combination of practices that has gotten us to where we are, and tillage is definitely one of those.” Lesley Atwood reinforced that other practices that should be considered when undertaking this systems-research include cropping rotation, pest management, and fertilizer management practices.
Tim Searchinger reinforced this point further that research should be designed to measure the benefits of no-till in synergy with other benefits:
“I think there's certainly the potential for synergistic benefits and combining practices, but they just have to be demonstrated through studies that show the synergistic benefits of combining practices. But then it’s important to say that your benefit from the no-till will occur if, but only if, you combine it with the following practices…if the benefits depend on the synergy, you have to be clear that it's the synergy that needs to happen.”
Involving Real-World Farmers in the Research
Panelists acknowledged a need to involve farmers when designing research to study the impacts of no-till. Lesley Atwood emphasized this point:
“Expanding our research onto farms will add a lot of benefits to our data and our understanding of how to integrate these practices and optimize multiple outcomes. Utilizing farmers’ knowledge and experience is key.”
Bianca Moebius-Clune highlighted the importance of conducting research among farmers who have adopted soil health management systems (including no-till), as well as their neighbors:
“I think that there's a really clear path, and, thanks to the hard work of many who see this critical need, the Farm Bill funded the first soil health demonstration trials, with a mandate that the research be done on commercial farms so that farmers use their expertise – they do the farming, and researchers use their expertise – they do the research and quantification work. This way we can work to compare these systems. We can compare farms of innovators who are managing for healthy soils using soil health management systems principles, with their next-door neighbors that follow standard conventional practices in a county for those commodities, and truly quantify the systems outcomes.”
Improving the Quality of Research Done on Research Farms
Barry Fisher highlighted the importance of ensuring research is supported by cutting-edge production equipment and technology:
“[A] lot of the research is still going to be done on university farms -- that's where much needs to be done, because you can control methods and variables. Let's get some of the best accepted technologies onto those research farms so that researchers and grad students can begin their research where the top farmers already are, from a technology and management standpoint. Going into the future, we need to be as predictive as possible on the benefits of no-till cropping systems. By implementing no-till with the technologies, strategies and science gained in the last decade, our likelihood of true benefits on a broad scale is very possible. To focus on data collected from plots 10-40 years ago will lead to mixed messaging. This is not your father’s no-till (to coin part of an ‘80s Oldsmobile commercial). If we refocus research energy from whether we should integrate no-till, to finding the best methods and intentional strategies for highest success and benefits, then farm sustainability, field trial results and the environment will improve greatly.”
The Challenge Is Daunting, But Achievable
Overall, our discussion highlighted several important uncertainties that will need to be resolved to fully understand the climate change mitigation impact of no-till, and also suggested a degree of urgency around addressing these challenges. Bianca Moebius-Clune noted “If we’re really going to be serious about food security for the globe, that means that we have to put our resources toward that goal.”
Tim Searchinger closed the discussion suggesting that conducting the research necessary to quantify no-till’s climate mitigation benefits is not an insurmountable obstacle:
“It doesn't really take that much money – I mean it takes a lot of money by comparison with what we've been spending for this type of thing, but in the larger scheme of things it's not that much money. We could do a lot of careful testing and analysis, and work on consistency and protocols, but this is not super complicated – it just means making a serious effort. It's not an intimidating amount of money – we could actually do it.”
This expert discussion of no-till agriculture took place in January 2022.