By Richard Cornett
Director of Communications
Western Plant Health Association
You might hear the words “agricultural sustainability” tossed around during a conversation that mentions organic food production as a sustainable answer in feeding the globe’s rapidly expanding population. For some, it might be more than a little confusing defining exactly what sustainability is, and how to use this measure to determine if organic food production has a sustainable advantage over conventional methods utilized in today’s modern farming practices.
There are some definite upsides and benefits that come from many organic farming methods. For example, the efforts of organic farmers to move away from monocultures, where crops are farmed in single-species plots, are fantastic; crop rotations and mixed planting are much better for the soil and environment. But there are other aspects of organic agriculture that should be considered. My goal is to bust the modern myth that organic food production is more sustainable in the long run than conventional crop production techniques.
A good article (“Nitrate leaching from intensive organic farms to groundwater,” Hydrology and Earth System Sciences) came out recently documenting higher groundwater contamination with nitrates under organic greenhouses because organic growers can’t “spoon feed” fertilizer through the drip, and depend on compost for which the release is not matched with plant uptake. The article was written by a handful of soil scientists and highlighted this specific finding: “Surprisingly, intensive organic agriculture relying on solid organic matter, such as composted manure that is implemented in the soil prior to planting as the sole fertilizer, resulted in significant down-leaching of nitrate through the vadose zone to the groundwater.” (The vadose zone is the part of earth between the land surface and the position at which the groundwater is at atmospheric pressure.) Elevated nitrate levels in groundwater are hardly a mark of sustainability.
Additionally, researchers affiliated with the Institute of Organic Agriculture in Switzerland and the Institute of Agricultural Sciences in Germany published a meta-study in which they conclude that organic farming methods lead to higher rates of carbon sequestration in soils. This work was published in a well respected journal, Proceedings of National Academy of Sciences.
All forms of farming, including organic, can lead to soil emissions of methane and nitrous oxide. The glaring issue that is problematic in organic farming is emissions of those gases associated with composting. Most people might think of composting as a very “green” thing to do, but few realize that composting actually generates a significant amount of these harmful greenhouse gases.
Organic farming isn’t more “green” than conventional farming. Although organic farming might be better for local environments on a small scale, this method produces far less food per unit than conventional agriculture. Organic farms produce around 80 percent of what a similar-sized conventional farm produces (some studies place organic yields below 50 percent of those of conventional farms). The unfortunate truth is that until organic farming can rival the production output of conventional farming, its ecological cost due to the need for more cropland is devastating.
This shortfall of reduced organic crop yields is driven by limited pesticide options, difficulties in meeting peak fertilizer demand, and in some cases by not being able to use biotech traits. If organic production were used for a significant portion of crop production, these lower yields would increase the pressure for new land-use conversion – a serious environmental issue because of biodiversity and greenhouse gas ramifications.
Another consideration regarding organic production is that the best approach to building soil quality is minimizing soil disturbance (e.g. no plowing or tilling) combined with the use of cover crops. Organic growers frequently do plant cover crops, but without effective herbicides, they tend to rely on tillage for weed control. There are efforts underway to find a way to do organic no-till, but they are really not scalable.
Between rigorous, science-based research and regulation, public and private investments in new technology development and farmer innovation, modern agriculture has been achieving remarkable environmental progress and will continue to be sustainable.