Posted on December 20, 2012 by Andy McGuire
Last summer, I visited an organic farm in the area. The farmer showed me various parts of his operation, one of which was a field that he had planted to a species of perennial grass that produces an abundance of deep roots. We dug a hole and confirmed it; a dense fibrous root system had formed after two years of growth. The farmer’s goal in planting this grass was to build up the soil before vegetable production. When I talked to the farmer again this fall, he was trying to figure out how best to go from the grass to vegetables. There could be two options for doing this.
The first is to till the grass crop in order to kill it. This would most likely require disking the soil three times or plowing and then disking, to kill the grass and break up the sod that is turned up by the first tillage pass.
The other option would be to spray out the grass crop with an herbicide. One pass through the field and the grass would be killed completely if done right.
If the goal of growing the grass was to build up the soil, which is the best option? Tillage, we know from research, would break up the physical soil habitat built up over the two years, disturbing the microorganisms living there. It would also disturb or destroy larger soil fauna, such as earthworms. This physical destruction, combined with the flush of oxygen that comes with intensive tillage, would burn up much of the organic matter added by the grass. The tillage would also eliminate soil cover and leave the soil in a loose state that predisposes it to future compaction.
Spraying out the grass with an herbicide would leave the soil’s physical habitat intact. The root mass that we dug up last summer would be undisturbed and the surface would covered by the dead grass leaves, controlling wind erosion and reducing evaporation.
In terms of the goal of building soil, the second option is plainly better than the first. However, some may argue that herbicides are toxic, that they may be a detriment to soil organisms, or that they could pollute the environment. If we used the herbicide glyphosate (the active ingredient in Roundup) its toxicity is low compared to other herbicides (the EPA considers glyphosate to be non-carcinogenic and relatively low in toxicity). The toxicity concern is limited further because we are not spraying a crop that is going to be harvested and the chemical is not persistent in soils. Any detrimental effect to soil organisms would be minimal compared to the obvious effects of tillage. Glyphosate also has a small leaching potential. For building soil, the choice is clear; spray out the crop.
However, these tradeoffs between using tillage and an herbicide do not fit in the black and white ideology of the organic standard. Although the standards claim to make soil quality/health a priority, in this case the standard’s dogmatic ban on synthetic pesticides wins out. In the end, this organic farmer, who is trying to do a good thing in building his soil, is hamstrung by ideology. He will end up tilling the soil and losing much of what he was trying to accomplish. And there are wider implications.
To give the consumer a clear, black and white choice, organic marketing strategy offers a black and white world where all human-made pesticides and fertilizers, and all genetically modified crops are bad, regardless of their value to farmers or to sustainability. Even limited use is prohibited because it would blur the marketing lines. This fear-based marketing strategy requires these complete bans.
However, I believe that in a rational, science-based system, abuse or overuse of certain tools does not invalidate their use. Such a system would give priority to farmers’ efforts to better conserve and build soils over important, but lesser concerns. It would facilitate development of “near-organic” no-till systems in Western Washington, where the difficulty of killing cover crops under organic standards make this near-to-impossible to implement now. I think this would be a better way to steward our soils.
By Chuck Benbrook on December 20th, 2012 at 9:42 am
There is no denying that there is rich diversity in views, opinions, and experience at WSU, and even within the Center Andy and I are associated with, CSANR. The prohibition against use of synthetic pesticides in organic certification rules around the world is grounded in two principles, neither of which deserves the derisive label “ideology.” Organic principle number 1 calls for farming methods and tools to be derived from, or reflect to the full extent possible nature and natural systems, while passing up “treat the symptom” solutions, especially those dependent on routine applications of synthetic chemicals. Principle number 2 is that there is an ecological and biological solution, not dependent on chemicals, and perhaps not even dependent on much other than a little diesel fuel, for most pest and fertility problems. Of course, these sort of solutions can be hard to find, and fleeting, but let’s be honest, collective American ag has not put much effort into it, and there is a pretty impressive record of food security and sustainability in cultures that have.
To Andy’s specific topic — using Roundup to kill a cover crop — I agree that it would be helpful for organic farmers to have new tools to kill cover crops that are less costly and disruptive than tillage. Some research is underway working toward the development of such tools, and someday a really lucky scientist is going to find an organically acceptable, broad-spectrum herbicide that works as well as spinosad, a bioinsecticide for which certain formulations are approved for organic production. But until then, organic farmers who stick with it will keep placing greater weight on adherence to a set or time-tested principles, and forego the quick-fix that spraying Roundup would entail. Whether using herbicides to kill cover crops is as benign as Andy suggests opens up another can of worms.
By Andy McGuire on December 21st, 2012 at 10:22 am
Chuck, please substitute the word “philosophy” for “ideology” if that is less derisive in your view. “Hamstrung by principles”, or just “hamstrung,” would also work for the point I am trying to make.
I am glad you brought up the organic principles, because it is just that dogmatic adherence to those principles by organic farming, which I contend, in this case, hinders sustainability. It is a clear case where the principles have become limiting to the goal. Here, the benefits of building soil that would come by using glyphosate to kill the cover crop are evident and beyond argument. However, the risks of using the glyphosate in this specific case are not clear and are very open to argument. Strict adherence to the organic principles does not allow the farmer to weigh of the benefits of using the glyphosate with the risks in a rational, science-based manner.
My post was not addressing all pesticide use, only a specific situation and product, and so your reference to “quick fixes” (why, in this case, is glyphosate a quick fix and tillage is not?) and “treat the symptom” solutions, do not apply in this case.
I have heard several researchers say that glyphosate is an once-in-a-lifetime discovery. If this is true, I would not bet much on finding the organic equivalent soon or ever. While waiting for this miracle product, how many farmers’ soil building efforts are being limited by their reliance on tillage?
And regarding worms, I would welcome a comparison of your “can of worms”, focused on the risk of using glyphosate in this situation, with all the worms that will be killed by multiple tillage passes if glyphosate is not used.
By Chad Kruger on December 21st, 2012 at 4:34 pm
I think a really important distinction to draw in this discussion is between consideration of general principles and specific circumstances. Like any set of standards, the organic standards create a set of rigidly defined practices (or prohibitions) that are generally supportive of a desired sustainability outcome, but that can be counter-productive in specific situations. To have such a set of standards that are enforceable, they have to be sufficiently generalizable across a jurisdiction (ie. nation-wide) – which tends to make them inflexible. In contrast, an agro-ecological based approach necessarily begins with an evaluation of site-specific conditions and management decisions are generally full of sustainability trade-offs that must be made.
The question of whether or not tillage in an organic system supports our sustainability goals is a perfect example of this “lack of black and white”. We know from the work of UW geomorphologist David Montgomery that tillage is the primary driver of the “erosion” of most historical civilizations — so it seems that the use of tillage in organic systems runs counter to sustainability goals. In the rich, deep, fertile soils of the Iowa corn belt, the rate of erosion due to tillage is a seemingly less pressing concern than the immediate concerns around use of pesticides (even relatively “safe” pesticides).
However, like those who experienced the Dust Bowl in the Southern Plains, we who have lived and worked in the inland Pacific Northwest know very well that tilling our fragile soils is extremely destructive and unsustainable. We are “textbook famous” for images of gullies in our Palouse fields and dust storms reminiscent of the Dust Bowl in the Columbia Basin. With the available technology and management practices we currently have to work with, the trade-off of choosing between tillage or herbicides is a very stark and unfortunate reality.
I have great appreciation for the principles that ground the organic standards – and for the most part they are consistent with what I see as a sustainable pathway forward for most pest and fertility management needs. The clear exception is the dependence the standards currently create on mechanical tillage (which is neither biological, ecological or natural) – especially here in the inland PNW.
While we have come a long way in designing and implementing agro-ecosystems in the inland PNW that are less reliant on tillage, we still have a long way [further than we've come?] to go. Like many of my soil science colleagues, I think that “saving and restoring our soils” is still the single most important production sustainability goal we have to tackle in our region. The reality is, we can’t continue to watch our fragile soils wash and blow away – or there simply won’t be anything left to debate….
By Maurice robinette on December 21st, 2012 at 5:15 pm
I would like to get all three of your perspectives on what would happen if the grass were grazed into the dirt, or ” mineralized”
As Ann Peschel calls it. Then no-tilled with a good drill.
By Chad Kruger on December 21st, 2012 at 9:54 pm
Maurice, I think, in the long-run, the use of livestock as a weed control / nutrient cycling strategy probably is part of the solution. But, it would need to be coupled with some more innovative cultural strategies to help the planted crops compete with grass regrowth (which would occur). Likely only the most vigorous crops could compete, which might have implications for rotation diversity. It would make some interesting experimentation.
By Theresa Lim on December 22nd, 2012 at 7:27 am
Why not look to permaculture principles and use sheet mulching to kill the grass? Granted it takes longer but preserves the soil integrity without chemicals. A rotational system would keep some of the acreage in production at all times.
By Chuck Benbrook on December 22nd, 2012 at 8:16 am
While tillage is generally bad for soil structure in all systems, one of the benefits of well-managed organic system is potential to change the “K” (Inherent erosivity) factor in the Universal Soil Loss Equation in a positive direction. While the soil scientists among us can explain this in much more detail, with proper terminology, the “K” factor captures the degree to which soil microbial communities emit the sticky substances that help bind soil together in stable aggregates. Work in the Midwest has shown on many farms that the “K” factor can be reduced ~30% on organic farms with good soil tilth. This reduction, coupled with farming relatively flat land using organic systems, avoids serious erosion losses, and indeed can even allow soil organic matter to gradually rise, until the regional threshold is reached. I suspect this benefit is limited in sloping, highly erosive PNW soils, which is why a different mix of practices are going to be needed here. Had not thought of the use of animals.
By RachaelL on December 24th, 2012 at 9:56 am
This post (and the comments) strike me as arguing for outcome-based agricultural standards and marketing. As pointed out, the organic standards (as there are several) are partially about marketing and to provide consumer trust they have to specifically say what can and can’t be used in organic production methods. They are thus fairly black and white and restrict use of some tools even when they might be better than the allowed ones.
If our marketing and labeling were about measured impacts like soil erosion, runoff of pesticides (normalized to EIQ or similar), water use, greenhouse gas emissions, etc. farmers could be free to use whatever methods they find most effective and compete on least environmental impact in the market rather than a complicated and not always about least impact standard called “organic” (never mind the various definitions and public misconceptions about what “organic” actually means). It would be pretty complicated to implement (how do you roll those impacts up in a consumer understandable way? how do you handle processed food?) but it seems worth it. The side benefit is the only way to honestly implement such a scheme would require a lot more monitoring of those impacts, which seems like a good thing to me though hard to support politically on its own.
By Anastasia Bodnar on December 24th, 2012 at 12:43 pm
Like Rachel, this post and comments clearly show to me that organic requirements don’t allow organic farmers the freedom they need to actually meet the goals (at least as I see them) of organic – farming with reduced environmental impact. The line drawn between “natural” and “not natural” is arbitrary and not meaningful or science-based. If the organic rules were actually based on something meaningful, perhaps more food would be produced organically (and it would actually mean something!). More farmers would see the value in transitioning to organic and I would wager that organic yields would increase. It would be complicated to implement, but organizations exist to help farmers make decisions about what methods to use, such as extension and groups like Rodale.
Now, how to get this information to consumers in a meaningful way? I’ve proposed that the various methods be valued in a science-based way to create a composite score called an e-value (e for environment, though surely someone could come up with something else!) – sort of like an EIQ but encompassing more factors. Single ingredient products would have one score that combines all of the methods used. A multi ingredient product could have a label saying something like “all ingredients e-value 90 or higher” or simply “90+”.
How cool would it be if we could consider price, nutrition, and e-value numerically to the quality in our decisions of what to buy!? Here’s hoping consumers become aware that a simple “organic” vs “not organic” distinction isn’t as useful as useful as marketers would have us think, and that some creative academic can come up with a useful composite system :)
By Chuck Benbrook on December 24th, 2012 at 1:30 pm
Good comments Rachel. Different approaches to farming should definitely be analyzed and compared using a set of science-based indicators linked to things people care about — like protecting an infant’s developing brain from impairment from pesticide exposures, or sustaining soil productivity and water quality. The new M2M program in CSANR is dedicated to developing and applying such measures. I am looking forward to carrying out many such comparisons between different farming systems and technology, as the M2M analytical system becomes operational.
It will be interesting to see how organic systems come out when compared to well-managed conventional systems. Most past studies that have made unbiased comparisons that take into account medium and longer-term impacts conclude that organic systems are superior on energy-based, pesticide risk, and soil quality indicators, while conventional systems are usually superior on yield and minimizing labor, or labor costs/bushel. One of the tricky things in carrying out on-farm comparisons is that “conventional” agriculture has become, in many places, more like organic farming systems than the calendar-spray, chemical-intensive systems of the past. This point was driven home in the great paper by my colleague John Reganold et al in PlosOne on strawberry fruit quality. They compared multiple sets of organic and conventional strawberries in the Watsonville area. Most of the matched pairs of organic and conventional fields were managed by the same farmer, and in most cases, several proven, profitable organic practices had been adopted across the whole farm. While this convergence of systems seems almost a global trend in fruits and veggies, the opposite is true in corn, soybeans and cotton, where GE crops, and the system they have brought on, doubles down on many of the problems with old “conventional” agriculture, especially excessive use on one or a few herbicides.
By William Price on December 24th, 2012 at 2:47 pm
C. Benbrook: Your M2M program looks to rely heavily on PRiME. Is there more information on this (sorry, I did not see it in a quick Google search or on the IPM Institute site). Has this been used before and how would it differ from the existing EIQ, mentioned above?
By Chuck Benbrook on December 24th, 2012 at 5:10 pm
William — The M2M analytical system does encompass pesticide use and risk, but covers much more. Human pesticide risk is measured via the Dietary Risk Index I have been developing/working with for 15 years. The DRI is also used in PRiME to cover human risk from residues in food. Down the road when PRiME is fully operational, we will draw upon it in some way to address the environmental impacts of pesticide use. FYI, PRiME started out with PEAS (Pesticide Environmental Assessment System) that was developed in the 2002-2004 period. PEAS was developed by a team including Jennifer Curtis, Chuck and Karen Benbrook, and Pierre Mineau. The goal was to create a more science-based way for Gerber to choice which pesticides/pesticide uses went on its “Do Not Use” list. PRiME was created in the 2006-2009 period with a 3-year CIG grant to the IPM Institute from the USDA-NRCS. It remains, like all pesticide risk assessment systems, a work in progress.
By Andy McGuire on January 4th, 2013 at 11:27 am
Maurice, I agree with Chad’s comment. The problem with using livestock is that the grass would regrow. We are going against nature in trying to kill the grass, so our solution, whether tillage, herbicide, or something else will probably not be “natural.”
Theresa, sheet mulching would works great on small areas, like a garden, but it is not practical to apply the depth of mulch needed to kill a perennial grass on large fields.
Rachael, I agree that outcome-based standards would be ideal, but as you said, very difficult to implement. It also bring up questions like how to rank different outcomes, for instance addressing the clearly evident and widespread issue of soil erosion vs. the less clear, and less easily observable issue of pesticide exposure.
Anastasia, I think your idea of a composite system is intriguing, but again difficult to implement. Once a system is used in marketing, it is pushed to become more black and white, creating the artificial separation of the good farmers and the bad farmers, when the actual differences, as Chuck pointed out, are less stark and becoming less so over time. Perhaps policy, rather than marketing, would be an alternative, but I am not the person to address the policy question.
By Jay Bost on March 3rd, 2013 at 8:09 pm
What about the work being carried out on roller/crimpers and flail mowers at your own institution?!? http://smallfarms.wsu.edu/soils-compost/research/organicnotill.html
Seems an excellent compromise between tillage and herbicide use..
By Andy McGuire on March 4th, 2013 at 8:26 am
Jay, even those researchers doing the work you mention will agree that it is not easy to kill annual cover crops with the roller-crimpers consistently in our environment (Western Washington is where most of this work is being done). The timing of this operation with the right stage of the cover crop maturity is critical. If soil or weather conditions do not allow the operation to proceed at the right time, some of the cover crop plants survive and then become weeds with tillage the only option in organic systems. Given this, I do not see how it would be possible to kill the established perennial grass crop that I wrote about with these tools.