In response to Craig Cox’s March 26th webinar, “The Farm Bill and the Environment: Missed Opportunities and Where to Next” and audience members’ unanswered questions, I’ve dedicated this blog to looking at a variety of techniques available to farmers that reduce the environmental impact of modern farming. One might call them “sustainable” farming techniques, insofar as they implement more ecologically minded thinking into a system completely decoupled from such considerations. In the very least, these practices offer farmers concerned about what’s happening to our nation’s soil, ground- and surface waters, and insect pollinators (just to name a few) methods to mitigate the damage. While none of these practices represent a “silver bullet” solution to what we’ve come to realize is a flawed agricultural system, they are responses to the question that Craig Cox posed to listeners at the very end of his webinar: “What do we want from agriculture? Mountains of corn? Or something different, like clean water?”
Techniques such as conservation tillage, crop rotation, cover cropping, and integrated crop livestock systems fall within the sustainable agriculture paradigm and demonstrate that we are gradually articulating a response appropriate for the 21st century.
Conservation tillage is simply any form of cultivating the soil that leaves the vegetative remains of the previous years’ crop, such as corn stalks or dried stems of wheat, on the ground before and after planting. At least 30% of the soil surface must be covered with such plant material in order for benefits such as erosion reduction, water conservation, and wildlife food and cover to be realized. Conservation tillage can also reduce the energy required to till the field, thereby conserving fuel and reducing diesel emissions.
Crop rotation is a practice that farmers have long used, and is even evidenced in ancient Roman farming practices. Modern-day crop rotation typically involves rotation between just a few select plants, corn and soybean being the most common. However, rotating among even a small variety of crops from year to year, rather than planting corn every single year can bring multifold benefits to both the farmer and the environment. The alternation between corn and soybeans, or other legumes, for example, can be key in reducing pests each year. Four- or five-year rotations eliminate a steady food supply for one insect, which might not feed on the alternate crop. Legumes, furthermore, can help replenish nutrients, such as nitrogen, in the soil and, in turn, can reduce fertilizer use. In small-scale gardening, where the landowner might grow a wide variety of crops, crop rotation schedules can be an effective way to enhance soil fertility and drastically minimize the need for insecticides.
Cover cropping, or planting to cover bare soil in the off-season, can protect soil during the late fall, winter, and early spring when it is exposed to the elements. These secondary plants can provide livestock forage too. This practice is shown to increase water infiltration into soil, thereby reducing flooding and runoff, enhancing biodiversity, and attracting honeybees and other beneficial insects. For farmers, this translates into reduced erosion, better soil quality, nutrient retention, weed suppression, and even disease cycle disruption. For more detail on each of these benefits see the University of Minnesota’s Organic Risk Management chapter on rotation,found here. Plants such as hairy vetch, clover, or annual ryegrass are common cover crops. Farmers, however, are often slow to adopt cover cropping due to the extra seed cost, planting, and maintenance, all without obvious financial return.
And yet, recent studies show that crop rotation can, in fact, boost annual yield. One Iowa study indicates a “clear rotation effect resulting in higher yield levels after legumes at both sites that could not be achieved by application of up to 240 lb [nitrogen]/acre.” Another 2012 USDA study of the benefits of maintaining crop diversity shows that a more diverse system has the potential to use far less synthetic chemicals, and use them to “tune, rather than drive” the entire agricultural system. This is possible, researchers suggest, “while meeting or exceeding the performance of less diverse systems.” Although farmer uptake of cover cropping is slow, research is showing that the financial and environmental benefits might not be trivial.
To further demonstrate this point, results from one recent (2014) five-year study conducted by Iowa State University, for example, assists farmers in northwest Iowa in reducing nitrogen runoff and protecting the water source for a nearby community through cover crops, all while maintaining desired agricultural yield. In this case, researchers implemented a variety of cover cropping systems (corn/winter rye; hay/perennial grass; oat/red clover; soybean/winter wheat/corn). For more in-depth information on cover crop benefits and barriers to implementation, check out the Iowa Cover Crops Working Group, which conducts on-going research and programs related to cover crop innovation. For more information about selection and seeding methods of cover cropping, visit Purdue University’s extension resources such as their article “Cover Crops for Modern Cropping Systems.”
Another approach to sustainable agriculture is agroecology. Agroecology responds to conventional agriculture’s lack of “a deep understanding of the nature of agroecosystems” and provides methods on designing and managing agricultural systems that conserve the functioning of local and regional ecosystems. This approach aims to generate systems that are sufficiently productive but that are also socially just and economically feasible. Agroecosystems take both environmental and human realms into consideration and are understood to be “communities of plants and animals interacting with their physical and chemical environments that have been modified by people to produce food, fibre, fuel and other products for human consumption and processing.” Agroecology places an explicit emphasis on reducing external inputs and enhancing extant processes of nutrient cycling, predator/prey relationships, and symbiosis. This approach includes crop rotations and cover cropping in its suite of techniques and methods, along with polycultures, agroforestry systems, and animal integration into cropping systems. Collectively, these practices keep the soil covered for the majority of the year (achieving soil and water conservation), provide a steady supply of organic matter, enhance nutrient cycling, and encourage pest control through biological control agents (rather than chemicals).
A polyculture differs from crop rotation in its use of several crop species in the same place, growing simultaneously, thereby avoiding the hundred-acre farms planted solely in corn or soybeans. This attending crop diversity immediately offers the benefit of reducing vulnerability to pests and diseases. While the idea of incorporating greater diversity into the American farming system has certainly gained traction in recent years, the idea of polyculture is acknowledged as potentially useful, but economically very impractical since multiple crop species will demand a wider variety of watering regimes, nutrient profiles, and differing types of maintenance in general. In terms of resiliency, however, polycultures and their continued study, offer examples of systems able to withstand or respond more quickly to changes in climate or precipitation. Climate disruption poses significant challenges for conventional farming methods in the near future and developing knowledge on how to use resilient perennials and more sophisticated plant communities on farms may soon become an extremely valuable tool, and not only for US farmers.
Another practice that demonstrates the symbiosis that agroecology emphasizes is agroforestry, or the “deliberate growing of woody perennials on the same unit of land as agricultural crops and/or animals.” This premise is based on the idea that “there must be a significant interaction between the woody and nonwoody components of the system, either ecological and/or economical.” Basically, “woody” plants such as trees, shrubs, and palms, are planted within the same space and are incorporated into a single management program along with other “nonwoody” crops such as corn or alfalfa. Such a program provides an “interface” between resources provided by agriculture and forestry, and is a response to the unique combination of land uses commonly found in tropical, developing countries. However, as one might expect, this agricultural method encourages diversity on the land but also offers a host of other benefits too. Not only does “the intentional growing of trees and shrubs in combination with crops or forage” protect water resources, conserve energy, and create wildlife habitat, it also provides other useable products such as timber, fruit, nuts and feed. For more detail on practices such as alley cropping, tree gardens, aquaforestry, or protein banks see to the Food and Agriculture Organization of the United Nations’ Appendix on agroforestry systems and practices here.
Another elaboration on this theme of interconnectivity between a locally diverse agricultural regime is the integrated crop-livestock system. While a diversified system simply involves distinct crop and livestock systems, these rarely inform one another. Resources, in these common farming scenarios, are not recycled. An integrated system, on the other hand, can recycle by-products such as manure extremely efficiently, since farmers can use products generated by one component to support another facet of the system. In China, for example, integrating fish production with duck, geese, chickens, sheep, cattle or pigs has been shown to boost fish production by 2 to 3.9 times. Here, farmers use livestock manure as feed for fish and zooplankton, as well as fertilizer for grass and other plants. Farmers irrigate the vegetables from the fishponds, which produces, in turn, livestock feed. This particular example may only be feasible in specific climates, but it demonstrates the broader concept of an integrated livestock system. In Southeast Asia, an integrated system might involve livestock grazing under oil palm, a practice that utilizes previously unused ground vegetation, thereby increasing overall farm production while saving 40% of the cost of weed control. In these cases, livestock not only contribute nutrients for the land and a fuel source for the farmers through their manure, but represent a “savings account” for the farmer too. These cases may not reflect the reality of agriculture in the US, but the concept and potential for greater integration on and between previously divided farms is, perhaps, a viable one as policymakers and farmers explore new ways to make US agricultural more sustainable. For more detail on project design and integrated systems in general, see the report “Integrated Crop-Livestock Farming Systems” by the International Fund for Agricultural Development.
The applicability of such a concept in the US context is not entirely far-fetched. According to one 2007 Agronomy Journal study “Integrated Crop-Livestock Systems in the Southeastern USA,” there are many possibilities for building integrated crop-livestock systems into American agriculture. In particular, the southeastern US, due to its mild climate, has great potential for expansion of integrated agricultural systems. The essential elements of a successful integrated crop-livestock system are practices already covered, namely crop rotation, cover cropping, intercropping, and conservation tillage. If cover crops are grazed, however, this would provide an immediate economic benefit to farmers, especially when considering the financial barrier to practicing cover cropping. According to the same 2007 Agronomy Journal study, research in the Coastal Plain and Piedmont regions indicates that integrated crop-livestock systems can protect soil and water resources by reducing external inputs, while maintaining, if not increasing, economic return.
Such alternative practices to modern and “conventional” agriculture point to the ecological necessity of such integrated modes of thinking and the economic feasibility in such an approach. Craig Cox’s discussion highlighted the ways in which the US Farm Bill’s subsidies endorse environmentally destructive agricultural methods. A cursory look into more sustainable techniques broadens our view as to what is physically possible and suggests that we don’t have to accept the manner in which our food is grown according to the oft-heard argument that any alternative whatsoever is economically unrealistic.
For those interested in engaging further in this discussion, be sure to listen to our final webinar in the series. On April 22, Sarah Carlson, the research coordinator at the Practical Farmers of Iowa, will be speaking about helping farmers make science-driven choices that minimize their ecological impact in her talk: “Driving Sustainability: Empowering Growers with On-Farm Research” (12 pm EST). You can register for this event here: https://www4.gotomeeting.com/register/470665063.
For a recording of Craig Cox’s presentation please see this link: https://vimeo.com/91476388
To see the rest of our line up for the Frontiers in Food and Agriculture webinar, please see our events page here.