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Is No-Till Sustainable?

Posted by jenna.osiensky | February 16, 2023

Contributed by Drew Lyon, Endowed Chair Small Grains Extension and Research, Weed Science, Washington State University

In my mind, the purpose of a blog is to throw out ideas and have them discussed. With that objective in mind, I would like to discuss the sustainability of no-till annual cropping systems.

I attended my first no-till conference in 1990, the year I started my job as an assistant professor and Extension Dryland Cropping Systems Specialist at the University of Nebraska-Lincoln Panhandle Research and Extension Center in Scottsbluff. I had received my Ph.D. in Agronomy/Weed Science from the University of Nebraska-Lincoln in August of 1988. After a 13-month stint as a Technical Services Representative for American Cyanamid Company in Michigan, I started my job in Scottsbluff. As a weed science graduate student, I had not attended any no-till conferences, but in my new dryland cropping systems position, I thought it was important for me to attend these conferences and see what I could learn. So, in the summer of 1990, I attended the Great Plains No-Till Conference in Bismarck, ND.

I was impressed by all the positive results presented in favor of no-till crop management throughout the Great Plains, but also a bit surprised by the lack of any negative results. In my scientific training, I had come to expect counter arguments and viewpoints on almost every topic, but I heard none. As a weed science graduate student in the 1980s, several of my fellow students at the University of Nebraska were studying atrazine resistance in several weed species. We learned that overreliance on herbicides, especially on just a few herbicides, for example, atrazine, would inevitably result in herbicide resistance in weeds. At the time, no-till systems in the Great Plains were highly dependent on atrazine. It was cheap and effective, and it was used on a lot of acres. Roundup (glyphosate) was not cheap in the 1980s and 1990s, and it was used mostly for grass control because it was too expensive to use the rates needed for broadleaf weed control. In my mind, the Achilles heel of no-till at that time was its near total dependence on atrazine. This was bound to fail, and yet nobody was talking about it at the conference.

In the 2000s, glyphosate went generic, which greatly reduced its cost, and a plethora of new herbicides came to the market. This was just what no-till systems needed to remain viable. However, the Achilles heel did not disappear. Overreliance on herbicides in no-till cropping systems quickly resulted in one herbicide after another losing efficacy as weeds developed resistance to them. Now, however, there is no flood of new herbicides coming to the market to replace the herbicides we are losing to resistance. We are becoming more and more reliant on fewer and fewer effective herbicides, which will only hasten their demise as effective tools.

I have always been skeptical about the long-term sustainability of strict no-till cropping systems. While my research in western Nebraska convinced me of the many benefits that no-till systems provide, including reduced soil erosion and increased soil water capture and storage, I also saw the benefits of occasionally, and strategically, using tillage as part of an integrated weed management system. I also saw that successful no-till systems, like successful organic systems, needed to include sophisticated crop rotations to manage weeds. No-till winter wheat-fallow was just not going to work for long. I believe in bringing as many tools as possible to the fight with weeds. Voluntarily leaving all tillage out of a weed management plan sounds like tying one arm behind your back. It may be an interesting challenge, but unless you really up your game in every other dimension of integrated weed management, I’m not going to put money on you winning the 15-round boxing match with weeds.

I don’t have the answer for how much tillage is needed to keep weeds in check, delay herbicide resistance, and do as little harm to soil health as possible, but I’m pretty sure that never tilling is not sustainable in the long-term. More research is needed to better understand the effects of occasional tillage on different soils. Most tillage research compares always tilling to never tilling because treatment differences reveal themselves quickly. A young faculty member needing to get tenure and promotion cannot wait for 10 to 20 years to publish results from a study where tillage only occurs every 6 to 10 years. In addition to weed control, occasional tillage may also be helpful when applying soil amendments such as ag-lime, gypsum, manure, or biochar, thus killing the proverbial two birds with one stone. While tillage has been used too much in the past, and with dire consequences, I think there is still a role for tillage in an integrated weed management program.

I bet at least a few of you don’t agree with me. Please share your arguments with us. I think it is an argument worth having, even if nobody’s mind is ultimately changed.

6 thoughts on "Is No-Till Sustainable?"

  1. Steve Young says:

    The same argument could be made for those who say that using cover crops for controlling weeds in rainfed systems will never work. Going all in on not tilling has resulted in problems that you mentioned with resistant weeds. Perhaps it is not a matter of tilling or not tilling or using cover crops or not using cover crops for managing weeds, but figuring out more precisely where and when these techniques work and where and when they may not. The where and when are mutually exclusive and may not always work in tandem. A wet year is when cover crops would work. A sandy soil is where cover crops may not work. Same for tillage – when and where is often extremely spatiotemporally specific. You may not know how much tillage is needed to keep weeds in check and that has to do with the when and where, which are dynamic and hardly predictable. We have been broadcasting everything in agriculture since day 1 in hopes of hitting the target and this mentality needs to change and can. New technology is allowing us to get better and better at answering the when and where.

    1. Drew Lyon says:

      Steve, you make a very good point! Making universal statements about tillage, cover crops, or any practice, really, is unwise. I have frequently criticized the USDA-NRCS for making one-size-fits-all programs, so I should be a little more careful with my statements. Management decisions are driven by many factors. What is right for one soil and environment may not be right for another. We too often oversimplify and generalize because getting at the right answer is often much more complex than we want to admit or feel like we can adequately explain. While the statement “To till or not to till?” has a nice Shakespearean sound to it, you are right that it is probably not the right question. Perhaps the right question is more like “Where, when, how, and how often to till?” or plant cover crops, or spray herbicides, etc. I hope some of the exciting new technology that is coming to agriculture will allow us to better understand and manage the true complexity of these decisions.

  2. Hello Drew! I’ll respond by stating emphatically that; YES, NO-TILL IS SUSTAINABLE, providing you follow the rules established by Dwayne Beck at the Dakota Lakes Research Center near Pierre, SD., (field sanitation – surface cover – crop diversity, are three big rules). If you regularly ignore these, you won’t be no-tilling for long.

    Our operation has been no-tilling for 40 years. We abandoned all tillage, including the harrow in 1995. The learning curve has been quite high. We had to adapt Beck’s rules to fit our environment. We started quite shaky, but now we are very comfortable with our ULDDSS (ultra-low disturbance direct seed system), and see it as the springboard for the next step, –improving our soil biological health. We are not overly concerned about the loss of chemistry, or weed resistance to chemistry. Currently, our operation does not have any weed cultivars with known resistance, –and by the time we have to face that issue, we plan to have advanced our management skill to the point we don’t need synthetic inputs.

    This is my segway to the subject of, State Universities relevance for 21st century agriculture. Currently those of us, interested in rebuilding our soils production capacity, are joining local bio groups, turning to private research, and guru’s like Dr. Elaine Ingham of the SoilFoodWeb to acquire useful information. For the past 8-10 years I have sensed that our universities have not adjusted to 21st century agriculture. We have questions about soil-plant interaction, how soil health relates to plant health, how soil health effects weed competition, and how soil health relates to human health. I observe that the various disciplines within the school of agriculture are each looking down their own narrow disciplinary tunnel, looking for answers to questions, without inquiring of other disciplines, to whether they see a potential solution. One outcome of tunnel vision is your “back to the future” solution of “tillage”, –an easy copout, but very counter productive to achieving a healthy soil, –and that is NOT ACCEPTABLE!

    Members of our Bio groups are experimenting, each, doing something unconventional, and that information is being shared. There is a lot we don’t know, but some of what we do know is, –we can effect diseases and insect predation through plant nutrition. We have individuals that have experienced positive results using the nutrition approach. I see multispecies cover crops as being an essential part of our crop rotation, regardless of rainfall zone, if for no other reason, to add sufficient cultivar diversity to the rotation. How to incorporate them into the rotation to achieve a better ROI is the challenge. To my knowledge, no-one has dealt with weed competition yet, but we do have a manual: “When Weeds Talk”, by Jay L. McCaman, that gives us a starting point. It is a spiral bound, 140pg, 8×11 manual with all the weeds I’m familiar with, and it lists information on their nutrient, and soil preferences. My current thinking, is that we will be able to manipulate plant nutrition to reduce weed competitiveness.

    1. Drew Lyon says:

      Hello Tracy:
      Thank you for your engagement on this topic! I was hoping my question would motivate some dialogue. I actually agree with you that no-till can be sustainable, but it requires a much higher level of management than I see in many no-till operations. Dwayne Beck’s three big rules are very relevant. I am a big believer in crop diversity, but I also understand the economic obstacles that often constrain adoption of diverse crop rotations.
      Unfortunately, many no-till operations over the years have simply substituted herbicides for tillage without adopting adequate crop and management diversity, sanitation measures, etc. This has resulted in the development of herbicide resistance in weed populations, which is a threat to agricultural sustainability. Resistant weeds do not stay put for long.

      In the last few years, there has been some research published on the use of occasional tillage, and much of it is indicating that occasional tillage can be done with little negative effect on soil quality, and in some instances, it can even improve some soil quality characteristics. I think the old thinking that all tillage is bad for soil health is starting to be questioned in the scientific community. I think it is a generalization that does not hold true in all situations. I would argue that ruling out all tillage is in itself a bit of tunnel vision.

      The soil biome is getting a lot of attention these days, which I think is great; however, there is a lot that we really do not know yet about the complex and numerous interactions that occur in soil. Into that void has stepped more than a few snake oil salesmen who are more than willing to sell people what they want to hear. One of the problems of science is that it takes time to really understand how things work, but it takes a good salesman very little time to see and exploit an opportunity.

      Tracy, you have obviously invested a good deal of time and effort into crafting a system that works for you. There is much that growers and researchers can learn from each other. I hope you will continue to work with us on some of these issues. There is a very long discussion to be had on the relevance of state universities for 21st century agriculture, but I will have to start another blog for that topic.

      Thanks for sharing your thoughts on this topic with us!

      1. Drew,
        You are right, alluding to me having tunnel vision. I am in a tunnel looking from where we are, –with degraded soil, increasing synthetic inputs, increasing input costs, decreasing reliability of access to synthetic inputs, to where I want to be, –having built our soil’s capacity to raise crops without synthetic inputs. I have been working on this goal since 2015. It is so easy get diverted down various rabbit holes using old familiar technology to, for instance smooth our fields, extend the useful life of chemistry, etc. My sons and I have these discussions regularly. My recommendation is always, keep the course, figure out a way without regressing.

        You are right, stating that there is research indicating that occasional tillage may not be that harmful to soil quality. It’s easy for me to imagine these studies in an environment with high summer rainfall, high humidity, along with relatively high OM & SOM, –but that is not us! Our environment, with low summer rainfall, low humidity, and low OM & /SOM is not conducive to rebuilding our soils health, either physically or biologically, when you insert a practice like, tillage, even occasionally, back into the system. We are short in fungi and don’t know how to successfully populate them.

        You are right, stating that the soil biome is getting a lot of attention, but there is a lot that we really do not know yet about the complex interactions. This is where research should be centered, –learning about the unknown interactions associated with soil biology, and how plant growth and plant selection can be manipulated through these process’.

        One last parting comment to your first post about not knowing how much tillage is needed to keep weeds in check. Prior to 2-4D (mid to late 40’s), I remember my grandfather and father’s winter wheat being a mess, with jim hill mustard. My 30 plus years of stirring dirt only promoted weeds, never reduced them. It took chemistry to keep weeds in check. In recent years, as we increase soil cover, and reduce soil disturbance, we have seen a dramatic reduction in weed competition. When drones replace our field sprayer, reduction of wheel tracks will result in even less weed competition. When drones install “weed it” technology, we will be approaching the threshold for suspending the use of crop protection chemistry.

        1. Drew Lyon says:

          Hello Tracy:

          I think we have more things we can agree on than disagree on. As Steve Young pointed out in his comment, the impact of different management systems is spatiotemporally specific, that is, it depends on both place and time. As such, you are in a far better position than me to know the impact of various management practices on the land you farm. I think that part of my job is to provide growers with weed control options that may make sense for them and their operations, but the options chosen are best made by the grower based on their specific situation. I learned long ago that there is no one right way to farm.

          I just read an interesting article in the latest issue of Weed Technology, which is published by the Weed Science Society of America. The article is titled “Sustainable weed management – What is it and how are we doing?”. The authors state “While the overall trend toward chemical weed control has been shown to decrease agriculture’s impact on the environment, depending solely on herbicides is not sustainable long term with the rise in herbicide-resistant weed species.” So perhaps a better question than the one I posed – Is no-till sustainable? – would be “How do we make no-till sustainable without heavy reliance on herbicides?”

          Robots, drones, AI, and machine learning are all technologies with great promise, but I suspect they will take a while to become useful tools, and they will likely come with a hefty price tag, at least for the foreseeable future. It will be necessary to fit these new technologies into an integrated weed management system that uses as many different practices as possible to manage weeds. I believe that occasional tillage is an effective management tool for some weeds, but if tillage does not make sense for a particular farm, then the grower will need to avoid the all too commonly used option of merely replacing tillage with herbicides. They will want to use as many different Best Management Practices as possible to keep weeds under control. The demands on management are increased when tillage is taken out of the equation, but there are many examples of successful no-till farming. Although herbicide resistance in weeds will increase the demands on management, I have no doubt that no-till systems are sustainable, but I think in many cases they will need to look different than what we see today.

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