It is likely that at least 170,000,000 acres of actively-sown annual field crops in American farmscapes are now depleted of their formerly-abundant milkweeds and monarch butterflies. This depletion has accelerated since the widespread adoption of herbicide-tolerant corn, soy and cotton crops grown where glyphosate herbicides are used to control field weeds.
As this combination of biotech and chemical agriculture has been adopted by more corn and soy farmers in the Midwest, scientists have documented a 58 % decline in milkweeds & an 81 % decline in monarchs from 1999 to 2012 in the farmscapes which formerly served as the summer habitat for monarch larvae and butterflies.
However, since 2002, weed scientists studying these herbicide-dominated agricultural systems have questioned whether this technological package have substantively reduced farmers’ costs or enhanced yields [Martinez-Ghersa, Worster and Radosevich 2003]. Instead of solving farmers’ weed problems, it has selected for at least a dozen superweeds whose populations have become herbicide-tolerant in North America. As one weed scientist has voiced his concern, “many growers have abandoned the principles of sound weed and herbicide resistance management [that utilizes multiple herbicide sites of action [such that] the diversity of [control techniques] used for weed management in these crops has declined…”[Young 2006]. Another critic, Washington State University’s Chuck Benbrook , has amply documented that overall herbicide use on soy has gone up since 1995. In fact, soy and corn farmers’ spraying costs have risen five- to seven-fold over the last decade, even though successes in weed control have begun to decline. Because of these rising costs and diminishing returns, many farmers’ are now imperiled, and in some states, a fifth of the farmers who have used herbicide-tolerant crops and heavier doses of glyphosates claim to be dissatisfied with their results.
What You Can Do:
- Promote a reduction in the use of glyphosate herbicides that are damaging to milkweeds by giving incentives to farmers willing to adopt integrated weed management that combines crop rotations, judicious tillage of weedy patches in fields, and crops that naturally emit weed-suppressing [allelopathic] phytochemicals.
- If natural or manmade herbicides must be utilized, assure that a diversity of them are used in small amounts in a targeted manner that”tunes” rather than drives the entire integrated weed management effort.
- Before mid-July, flag milkweeds that have emerged in field patches separate from those of superweeds, and minimize tillage, mowing or spraying until after monarchs have migraed.
- Set aside on-farm pollinator refuges in green belts beyond field edges, in hedgerows or wetland perimeters.
- Plant native grasses, milkweeds and wildflowers in green filter strips, also called or prairie conservation strips, on ten percent of a row-cropped field or watershed. These can not only attract monarchs and other beneficial insects, but redice sediment transport, soil erosion, and enhance soil fertility as well as yields.
- Adapt and refine other forms of low input, highly diverse [LIHD] agriculture to make safe havens for milkweeds, monarchs and bees while balancing productivity, profitability and environmental health for family farmers and their farmworkers.
There are many forms of low input, highly diverse agriculture in the world, some of which are better for maintaining milkweeds, monarchs and other pollinators than others. Over a nine year study from 2003 to 2011, more complex crop rotations of grains and legumes at Marsden Farm boosted yields while slashing herbicide applications by 88 percent compared to the simplified conventional system. These kinds of rotations are part of integrated weed management systems that suppress the further development of superweeds, but they do not necessarily allow for the survival and proliferation either. However, they can be integrated with the practice of planting prairie conservation strips or green filter strips that retain pollinator habitat while reducing the loss of soil fertility . Some researchers have demonstrated a 380 cent increase in native plant species in croplands with intermittent conservation strips as green filters and safe havens, compared to entire watersheds entirely put into row crops of annual grains or legumes.
As Iowa State University agroecologist and STRIPS team leader Matt Liebman has explained, “Focus on filter strips that both reduce soil nutrient loss and potentially decrease the risk of creating herbicide-resistant weeds. All these characteristics are aspects of increased system resilience.”
While Mardsen Farm is a university research and demonstration farm, commercial farms across the country have also had successes in enhancing pollinator populations and crop yields with their own versions of Low Input High Diversity agriculture.
At Singing Frog Farms in Sebastopol, California, farmer Paul and Elizabeth Kaiser has planted more than two thousand individual perennial plants of one hundred and eighty pollinator-attracting species around his rows of fruit bushes and vegetable fields. Compared on a per acre basis, Paul and Elizabeth’s efforts economically yield four to five times the gross income that their neighbors gain from their simplified conventional and organic farms. Anyone who has walked Singing Frog Farms with Paul cannot imagine a single person more deserving of the National Association of Conservation Districts (NACD) and North American Pollinator Protection Campaign (NAPPC) Farmer Rancher Pollinator Conservation Award he received three years ago.
In a similar vein, John and Nancy Hayden of The Farm Between near Jeffersonville, Vermont raise high quality organic apples, black currants, blueberries, strawberries, raspberries, elderberries, aronia, gooseberries, honeyberries, seaberries, and saskatoons in part because of the efforts they have made to attract honeybees, native bees, butterflies and other native pollinators to their sixteen acre pollinator sanctuary. They are committed to maintaining this sanctuary and haven for all pollinators by never using toxic pesticides, and by creating nesting and overwintering habitats and season long floral resources for monarch butterflies, bumblebees, mason, and ground-nesting bees. They do so by planting nectar and pollen producing natives such as milkweed, button bush, winterberry and basswood, and by using buckwheat and phacelia cover crops to provide weed control, build soil fertility, prevent erosion and provide habitat for beneficial insects.
As John Hayden from The Farm Between has noted, “ I believe it is our best bet to focus on field edges, borders, driveways, ditches, riparian zones, orchards, powerline right of ways and other non-cultivated areas that farmers can manage to enhance milkweed and other pollinator/beneficial insect plant populations. Farmers used to worry about weed seed inoculation coming from these areas, but since the advent of GMO’s and Roundup that is not as big a concern. If we use no herbicides in these pollinator habitat pockets, and reduced and effectively timed mowing, it could go a long way to bringing back beneficial plants like milkweed.”
The Union of Concerned Scientists has called these successes in butterfly-friendly alternative cropping systems “what agribusiness doesn’t want you to know.”
Further Reading and Links:
Anonymous 2013. A Landowner’s Guide to Prairie Conservation Strips. Iowa State University Leopold center for Sustainable Agriculture. Four pages on line at https://www.leopold.iastate.edu/pubs-and-papers/2013-08-landowners-guide-prairie-conservation-strips.
Benbrook, C. 2012. Impacts of genetically-engineered crops and pesticide use in the U.S.—the first sixteen years. Environmental Sciences Europe 20.
Davis, A.S., J.D. Hill, C.A. Chase, A.M. Johanns and M. Liebman. 2012. Increased cropping system diversity balances productivity, profitability and environmental health. PLOS One, October 10, 1371.
Hirsh, S.M., C. Mabry, L. Schulte, and M. Liebman. 2013. Diversifying agricultural catchments by incorporating tallgrass prairie buffer strips. Ecological Restoration 31: 201-211.
Jarchow, M.E., and M. Liebman. 2012. Nitrogen fertilization increases diversity and productivity of prairie communities used for bioenergy. Global Change Biology-Bioenergy 5: 281-289, doi: 10.1111/j.1757-1707.2012.01186.x.
Liebman, M., M.J. Helmers, L.A. Schulte, and C.A. Chase. 2013. Using biodiversity to link agricultural productivity with environmental quality: results from three field experiments in Iowa. Renewable Agriculture and Food Systems 28: 115-128, doi:10.1017/S1742170512000300.
Martinez-Ghersa, M.A. , C.A. Worster and S.R. Radosevich. 2003. Concerns a weed scientist might have about herbicide-tolerant crops: a revisitation. Weed Technology 17: 202-210.
Pendergrass, K., M. Vaughn and J. Williams. 2008. Plants for Pollinators in Oregon. USDA NRC Technical Notes, Plant Materials No.l3 .Portland Oregon.
Stilleman, K. 2012. Crop rotation generates profits without pollution [or what agribusiness doesn’t want you to know]. The Equation. http://blog.ucsusa.org.
Young, B. 2003. Changes in herbicide use patterns and production practices resulting from glyphosate-resistant crops. Weed Technology 20: 301-307.
Where can you see prairie conservation strips in action? Visit the Neal DSmith National Wildlife Refuge, 998l Pacific Street, Prairie City, Iowa, or call 5l5–.