By James Patchett
Major flood events can be traced to land-use practices, including modern agricultural methods.
The occurrence of flood events such as those that have ravaged the Midwest—most notably the two, 500-year floods in 1993 and 2008—were not “natural” disasters, as some contend. These, as well as other cases of chronic flooding can be directly connected to contemporary urban, suburban, and rural-agricultural, land-use practices.
Long-term solutions to chronic problems associated with water must address land-use practices that extend beyond urban and suburban environments into the predominantly agricultural watershed. If cost effective, ecologically restorative solutions are not incorporated into agricultural environments, river communities will continue to be subject to frequent, costly flooding no matter how many flood reduction or protection measures are implemented within their municipal boundaries.
Problems associated with increased runoff, erosion, sedimentation, flooding, aquifer depletion, water quality degradation, loss of habitat and biodiversity, and even climate change, exist in large part due to a fundamental lack of awareness of historical ecological and cultural processes. Many contemporary urban, suburban, and rural land-use practices—designed and engineered by professionals and accepted by the general public—produce adverse effects due to a lack of awareness of natural process which would mitigate such disasters.
It is imperative that we understand local geology, soils, flora, fauna, hydrology, climate, and the historical cultural influences that helped shape the “nature” of every place where we live. The fact is that there are realistic, cost-effective solutions for these problems across the spectrum from urban to rural locales.
The Agricultural Dilemma
It has become better understood that contemporary urban and suburban land-use practices cause substantial runoff, flooding, and water quality degradation. It is far less understood, however, that conventional row-crop tillage practices also contribute significantly to site and regional water resource management problems, including the increased generation of surface-water runoff and flooding; water-quality degradation from chemical and sediment pollution; and the contamination and depletion of surface and groundwater reserves. Row-crop commodity agriculture has also proved to be economically unsustainable without massive federal and state funding programs. Declining revenue, even in the corn and soybean biofuels boom, coupled with the increased loss of soil fertility and topsoil resources, has resulted in an economic “no-win” situation for many local agricultural producers.
Tillage exposes highly organic soil to the atmosphere, promotes oxidation of accumulated soil organic carbon, which in turn reduces the soil’s tilth and its capacity to absorb rainwater and hold nutrients. The loss of a strong, perennial ground cover exaggerates the rate and amount of soil loss to wind and water erosion. After several years of repeated tillage, the once-extensive root system of prairie vegetation disappears altogether and a once highly organic soil becomes primarily mineral in composition. Compaction and loss of root structure and organic-matter content alters soil density causing water infiltration rates and capacity to drop dramatically. Introduction of drainage tile acts to accelerate the rate of water loss, oxidation, and depletion of soil nutrients. In turn, crops need significant additional resources to grow including fertilizers and water. The impact of fertilizers, herbicides, and pesticides in our soil, and surface and groundwater systems is well documented, but other negative influences associated with annual, row-crop tillage are far less understood.
A 1990 USDA Soil Conservation Service (SCS) later changed to the Natural Resources Conservation Service (NRCS) study concluded that, of the original average 18 inches of topsoil across the state of Iowa at the time of settlement, ten inches had been lost to wind and water erosion, and that half the tilth was gone from the remaining eight. The long-term consequences on both the local and broader economy are frightening particularly in light of current conditions where many acres of Iowa farmland have lost all, or nearly all of their topsoil, and the average organic matter content of many Iowa soils is two percent or less. Once the organic matter levels are this low, coupled with altered soil structure, the land appears to have reached a critical “tipping point” with respect to its inability to absorb and hold water. We believe that this a primary reason for the increased frequency and magnitude of flood events.
As the water in the soil is drained away, the reduction/oxidation relationships change dramatically. Whereas once the prairies held their water, and carbon was fixed beneath the surface in net amounts, annual row-crop tillage now causes carbon to be oxidized more rapidly than it is fixed, a situation exacerbated by the constant drain of water through the tile systems and into the ditches. Consequently, during each growing season, carbon dioxide that was fixed millennia ago is now released into the atmosphere in amounts greater than it is taken up, which potentially contributes to the problem known as climate change. This net release of soil organic carbon (SOC) is not a minor concern. Recent studies on the amounts of carbon stored in the Conservation Reserve Program (CRP), in which deep-rooted native grasses are planted in some of the less productive or more erodible soils, have shown that ten years of SOC storage can be oxidized within a single growing season after tilling. In fact, more than 90 percent of the fixed carbon can be released in the first 15 days following tillage, and that net loss can occur within 30 days.
One pound of SOC, once oxidized, generates 3.4 pounds of carbon dioxide emissions. If the net SOC accumulation rate averaged 1 ton/acre/year for a ten-year cycle of CRP planted in native grassland, the CO2 emissions would equate to approximately 18,000 x 3.4 or 61,200 pounds of CO2 emissions/acre over a 15-30 day period. For comparison purposes, a car or lawn mower emits approximately 16 pounds of carbon dioxide and carbon monoxide for every gallon of gasoline burned. This is of course fossil carbon, the effects of which are of concern in our contemporary atmosphere. With the push for corn ethanol, much of the remaining CRP throughout the Midwest is rapidly being converted once again to production.
Soil and water loss, coupled with air and water pollution are not the only concerns. As described by my colleague at Conservation Design Forum, Dr. Gerould Wilhelm, when the rhizoshpere, which includes the deep root systems of the native bunch grasses is destroyed, a chain reaction of negative impacts is generated:
- a contiguous connection to the stable thermal mass of the subsoil ceases to exist;
- soil moisture decreases and the surface mineral soil, or other surfaces, become vulnerable to significant daily temperature fluxes;
- no longer able to thermo-regulate, many conservative organisms, including flora and fauna, have difficulty maintaining a stable metabolism;
- the land defaults to the few plants and animals that can survive such circumstances, while most native species are simply unable to compete;
- evapo-transpiration at the surface is drastically reduced, the moderating effects of water are lost, and the surface of the earth heats up;
- the shifts in temperature and hydrology-effect weather patterns, bio-diversity, and, in all likelihood, contribute significantly to global warming.
As the world-wide population and corresponding demands on limited natural resources continue to grow, the necessity for identifying and implementing sustainable agricultural practices that promote both economic and environmental stability becomes increasingly critical. These demands require new production approaches that can adequately provide for the needs of today’s world population, without sacrificing the needs of future generations.
Imagine an agricultural economy that provides a steady source of revenue generation for farm producers while promoting new local, community-based, economic development and multi-functional agri-based industrial growth opportunities:
- that acts to restore the ecological integrity of site and regional land and water resources, including the re-development of organic-rich topsoil;
- that isn’t weather dependent on an annual basis;
- that involves a production process which effectively reduces time and input costs;
- that results in the reduction or elimination of chronic growing season flooding, soil erosion, and sedimentation on a site, as well as at a regional watershed basis;
- that protects and enhances terrestrial and aquatic wildlife habitat;
- that improves regional water quality and replenishes depleted groundwater reserves;
- that enhances regional air quality;
- that provides for long-term revenue generation potential without the creation of collateral economic or environmental costs to society.
We believe that this is not only possible, but imperative, and that the process will be market driven and economically sustainable without long-term subsidies.
Today there are numerous examples of both newly developing, as well as age-old technologies and practices that can provide significant economic and environmental benefits to individual farmers and society as a whole. Many of these applications are already in practice in various forms throughout North America and abroad. In the upper Midwest, however, such practices will rely on the creation of new markets and industries based on locally grown, native-grassland bio-mass. The uses for locally adapted prairie bio-mass are varied and may include, but are not limited to, economically and environmentally sustainable ethanol fuel and energy production; and fiber production for paper, cardboard, insulation, rubber, plastic, cloth, and construction products.
A fundamental goal of this approach is to identify a more suitable balance between corn and soybean production, integrated with grassland restoration and associated sustainable-production practices. In addition to the education of agricultural producers, decision-makers, and the general public about the economic and ecological liabilities associated with conventional farming practices, it is critical to develop and promote market-driven solutions that can self perpetuate and do not owe their ongoing existence to constant federal funding.
The restoration of regional grassland systems for grazing, biomass, and seed production can generate multiple collateral agribusiness and economic development opportunities. Rotational grazing of cattle, bison, and elk to provide a healthy source of local meat production will be an important part of the equation. Another critical component will include the incorporation of local, sustainably grown and harvested fruit and vegetable production, which has proven to generate income on a per acre basis well beyond anything achieved in row-crop agriculture. New local industries will develop to produce and distribute the products that are generated including meat packing, produce, and paper and fiber production facilities. As with corn and soybeans, warm-season native grassland production will result in multiple revenue generation opportunities including local-ecotype seed production and sales, revenue for carbon credits, and a variety of useful bi-products, such as vanilla extract for human consumption.
Other potential offshoots relate to opportunities for regional wildlife and plant-habitat restoration, and the potential direct relationships to increased tourism. Imagine the interest that would be generated by traveling through hundreds of square miles of restored Midwest prairie and woodland systems. Wildlife species that are rarely seen today would likely return in abundance, and the opportunity to view herds of bison and elk would be compelling. With increased tourism comes the need for lodging, restaurants, and entertainment, to name a few. There are also tremendous opportunities for local education and outreach. Gaining an increased understanding of the unique cultural and natural heritage of where we live is critical to the long-term sociological, economic, and ecological well-being all of our citizens.
New Policies and Programs
A number of local, regional, state, and federal authorities throughout North America and other regions of the globe have recently enacted, or are considering, updated land-use and development codes and ordinances that promote the reduction of surface water runoff and on-site infiltration. Cities, for instance, have enacted Storm Water Utility taxation programs that tax new construction, as well as existing land uses, based in large part on the amount of impervious cover that exists within each site.
Imagine the advances that could be made in this arena if we spent one-tenth of the time, energy, creativity, and money focused on the identification and implementation of practices designed to treat water as a resource rather than a waste product. Flooding, water-quality degradation, habitat disruption, aquifer depletion, loss of bio-diversity, and most other chronic problems associated with the mismanagement of water could be significantly reduced or eliminated with the incorporation of truly creative design and implementation solutions. Although the magnitude of the problem may appear overwhelming, it is our belief, and our hope that education and understanding will foster change at a pace far more rapid than we may be currently able to grasp.
About the author: James Patchett, ASLA, LEED AP, is the founder and president of Conservation Design Forum, based in Elmhurst, Ill. He can be reached at JPatchett@cdfinc.com.
Republished from March, 2009 issue of Sustainable Land Development Today magazine.