Organic Farming Provides Ecosystem Service and Solves Weed Problems
Posted by Andrew McGuire | April 14, 2016
In nearly all surveys of organic farmers their top priority for research is weed control. Weeds are a tough problem to solve, but with creativity and spunk, researchers in Spain have done it! In their 2016 paper, “Arable Weed Decline in Northeast Spain: Does Organic Farming Recover Functional Biodiversity?” Chamorro et al. provide a unique glimpse into the sort of thinking it will take to move agriculture to a different place. In a series of unanticipated turns, the authors lead us down a path to weed-free agriculture.
First, they contend that weeds are misunderstood. Weeds, as the paper admits, are a bane of agriculture, reducing yields as they do, but in a subtle departure, we are then told “The role of weeds in agroecosystems has been largely debated.” From this debate, the authors conclude that “the role of weeds is manifold”; weeds are not just yield-robbing competitors of crops, they also provide an “ecosystem service.”
In my experience, farmers don’t debate weeds. Whether conventional or organic, they kill them however they can. The authors, however, having established the beneficence of weeds, redefine them in this new role as “arable flora.” And it is this floral biodiversity, the weeds, that is being drastically reduced by farming; “Our results indicate a remarkable reduction in weed frequency (58%), species richness (47%) and total weed cover (69%) from the 1953–1988 to 2005–2007 periods.”
This is not surprising given that agriculture has changed a lot over 50+ years. Furthermore, I would expect that this decrease of weeds would be accompanied by an increase in yield, but that is not their focus…
The arable flora that has the authors’ concern are not ordinary weeds, able to fend for themselves in the wild. No, these are “segetal and rare arable weeds that thrive almost exclusively in arable habitats.” Segetal? I didn’t know either, but the authors explain, “a subset of the arable weeds that thrive almost exclusively in cereal fields and that are characteristic species of arable crops.” These are the threatened biodiversity.
So, we have these segetal weeds that can’t survive outside a wheat field, and farmers have controlled them well so well that they are becoming less common. This is good right? Less weeds in the wheat, better wheat yields…wrong. The authors see this as a loss and have sounded the alarm through this paper. This is a call to save the weeds, or rather “floral biodiversity.” In an imaginative rethinking and then renaming, these researchers have solved our weed problem!
The authors explain that we should be concerned for this arable flora because they “provide food and shelter for a wide variety of farmland fauna,” the “birds, pollinators and other invertebrates such as phytophagous insects.” So, now we have birds, bees, and bugs dependent on weeds which are dependent on wheat which is dependent on the farmer, and the farmer has been doing their job too well.
I am all for birds, bees, and bugs (some of them). However, these birds (shall we call them arable avians?), that along with the weeds have become dependent on our agriculture – are we now responsible for their well-being? And if we are, how should we respond? The authors have a solution.
They report that their “results support findings that organic management allowed a recovery in the number, abundance and frequency of species. [of weeds]” More weeds, more species of weeds, and more of the ground covered by weeds, all with organic farming. Even better, “current organic farming practices may allow a relatively large number of segetal or rare weeds.” The segetals and, the authors presume (they did not measure this), the fauna dependent on them (the degree of dependence is not detailed) are saved by organic farming. The good news continues, “The translocation of weeds among fields and territories yearly from seeds from the previous year has the potential to increase the frequency, number and abundance of weeds in organic arable fields.” The spread of these weeds, when they produce seeds in organic fields, is an extra benefit, building to the inevitable conclusion, “This work… confirms the benefits of organic farming on biodiversity, in terms of the maintenance and restoration of the local floristic richness and abundance in cereal fields, including segetal and rare species, in relation to conventional crops.”
Here, in academic-ese, we have the failure of organic farming’s weed control reclassified as “biodiversity enhancement” which saves the weeds that can no longer live in the wild, which then saves the birds, bees and bugs that are dependent on these weeds. All of them will recover if only we stop controlling the “arable flora” so well, and organic farming is the way to do this. We should be grateful?
According to this line of thought, “The effects of herbicides and monoculture and the competitiveness of crop species soils highly fertilised by synthetic nitrogen inputs may have led to poor growth conditions for those species.” Look at that string of buzzwords, “herbicides,” “monoculture,” (wrongly used, they probably meant monocropping), and “synthetic…inputs,” all stigmatized because they create poor conditions for the growth of weeds “arable flora.” They have turned this true statement on its head revealing the true delusion of their thinking. First, farmers should not be blamed for producing a competitive crop; that is their job. Second, the job of herbicides is to kill weeds, so this says that they are also doing their job. Finally, I am in favor of crop rotations over monocropping, but crop rotations are also a good way to control weeds, especially those weeds that thrive in one crop, say wheat, but not in another crop; weeds like segetals!
In their fanciful story, the authors overlook, or have forgotten, that agriculture is not nature, that it goes against nature, and that it is a human construct, agri-CULTURE, not a natural one, and its goal is to provide food.
Regarding food, in this paper they fail to mention the cost of their segetal saving efforts, but in a 2013 paper (Armengot et al.), some of the same authors find that the weed-saving organic farms produced 23% less wheat per acre than the segetal-killing farms. This is the cost of saving the weeds and their dependent fauna. Maybe someday, after our population stabilizes, we can afford such luxury, but until then it is a zero-sum game – what we don’t grow on current fields will be made up by new fields cut out of nature.
In the tradeoffs between food production and nature that are inherent in agriculture, we need a little more “us vs. nature” thinking. The tradeoffs are simple. If you want more weeds, stop doing such a good job of controlling them, consider going organic, or better yet, stop farming. Too much time in comfortable affluence has dimmed the memories of being hungry, of crop failures, of eking out a living in the wilderness. In agriculture, we should do what we can to reduce bad effects on the environment, but if we do not work to get our share, something in nature will eat it or, like weeds, compete for a share of the water/light/nutrients that the crop needs to produce food for us.
Chamorro, L., R. M. Masalles, and F. X Sans. 2016. “Arable Weed Decline in Northeast Spain: Does Organic Farming Recover Functional Biodiversity?” Agriculture, Ecosystems & Environment 223 (May): 1–9. doi:10.1016/j.agee.2015.11.027.
Armengot, Laura, Laura José-María, Lourdes Chamorro, and Francesc Xavier Sans. 2013. “Weed Harrowing in Organically Grown Cereal Crops Avoids Yield Losses without Reducing Weed Diversity.” Agronomy for Sustainable Development 33 (2): 405–11. doi:10.1007/s13593-012-0107-8.