Initiated in 1987, the Kellogg Biological Station LTER (KBS) examines basic ecological relationships in field crop ecosystems to better understand internal processes controlling productivity independently of external subsidies (e.g., fertilizers, pesticides). The initial goal remains the same: effectively substituting ecological knowledge and theory in the agronomic management of cropping systems for a reliance on chemically based approaches. Research involves synergistic activities of long-term observations of contrasting cropping systems and successional vegetation, shorter-term field experiments, and modeling. Hypothesis testing relates to patterns and processes underlying ecosystem productivity and nutrient retention, including plant community dynamics, soil microbial populations, insect consumer dynamics, watershed and field-scale biogeochemistry, human interactions, and regional processes. KBS-4 is organized around the same initial hypothesis, albeit with a new conceptual research model and the addition of a new focus on valuation of ecosystem services. The model organizes ecological understanding of field crop ecosystems into components focused on ecological structure (e.g., organisms and their adaptations, population and community assemblages, and habitat structure) vis a vis ecological functions (e.g., biogeochemical processes, energy capture and flow, and hydrodynamics). Linkages between these components largely define the mechanisms that underlie the production of ecosystem goods and services, those products that provide the economic and social rationale for farming. Major research topics include plant community change, microbial processes, controls of arthropod communities, biogeochemical fluxes of solutes and trace gases, human valuation of cropland ecosystem services, and regionalization (scaling up via models).
Broader Impacts. KBS is an established leader in developing and using ecological approaches to improving our understanding of agroecosystems. KBS research deals with food production, a topic of global significance, and has ready practical applications to the ongoing development of mid-western US agriculture, as well as the potential to make significant contributions to the more general area of sustainable agriculture. Outreach and educational activities are robust at KBS. Research findings are reaching the media, local and regional agricultural communities, and other key citizen groups influencing land management. KBS places a high priority on connections with agricultural policymaking and global-change issues. Several KBS scientists have testified to Congress on agricultural issues and strong international connections have been forged. The site has a significant on-the-ground outreach program offering a wide range of service and educational opportunities to the broader community including agricultural extension services, informal education, university coursework, research experience for undergraduate and graduate students, and Schoolyard LTER activities for K-12 students and educators. Contributions to the LTER network include the publication of a soils methods synthesis book and participation in the diversity x NPP and LINX network-wide studies. The site is close to full adoption of the Ecological Meta-Language (EML2) format standard to ensure easy data exchange.
The Kellogg Biological Station (KBS) Long-term Ecological Research Project in Row-crop Agriculture At KBS we have built a long-term research program to examine important aspects of the ecology of agricultural ecosystems. We combine experimental studies with long-term observations of crop fields and landscapes. Over the last six years our research program has advanced scientific understanding of US row-crop ecosystems such as corn, soybean, wheat, and alfalfa. Of particular note is our progress in understanding 1) greenhouse gas fluxes, 2) soil microbial diversity, 3) nitrogen cycling and loss, and 4) crop pests and their enemies. Greenhouse Gas Fluxes. Since 1992 we have studied fluxes of the major, naturally occurring greenhouse gases -- carbon dioxide (CO2), methane, and nitrous oxide -- in a variety of cropped and natural ecosystems. Our research shows how different cropping strategies can have different effects on greenhouse gas fluxes. Twenty years of research show that conventional cropping methods have an annual global warming impact (GWI) of about 100 CO2-equivalents per square meter. Careful analysis reveals that nitrous oxide production is responsible for more than half of this impact, with the remaining half the combined effect of fuel and agrochemical use, including inputs of fertilizer, lime, and pesticides. However, results also suggest that almost all of the GWI of farming can be mitigated by changing management. No-till cultivation leads to soil carbon storage that almost completely offsets the GWI of other activities. Planting legume cover crops also helps. Taken together, results suggest that crop production could help to mitigate US greenhouse gas production. Microbial Diversity. Soil microbes are important catalysts of global carbon and nitrogen cycles, including the production and consumption of greenhouse gases. Some microbes produce CO2 and nitrous oxide while decomposing organic matter in soil. Others consume methane from the atmosphere, thus helping to mitigate climate change. To better understand the role that agriculture has on these processes, we studied microbial communities in soils across corn, soybean, and wheat fields, "old fields" that had been abandoned from agriculture, and forests. Results showed that land management has little influence on general microbial diversity, but greatly affects the diversity of microbes involved in methane oxidation: soils with a greater diversity of methane oxidizing bacteria consume more methane from the atmosphere. These observations suggest that managing lands to conserve or restore the diversity of methane-consuming bacteria could help mitigate climate change. Nitrogen Cycling and Loss. Agricultural landscapes commonly have excessive concentrations of nitrate (an especially mobile form of nitrogen) in ground and surface waters due to fertilizer applications in excess of what the crops can use. Nitrate that leaches to ground and surface waters can contaminate drinking water supplies and eventually a portion will be carried to coastal ocean waters where it will contribute to "dead zones" of low oxygen availability, such as in the Gulf of Mexico. We discovered how different farming practices can dramatically improve nitrate retention in grain crops. In particular biologically-based (organic) management reduced nitrate leaching by as much as two-thirds compared to conventional farm management. This is because organic management included cover crops like red clover that supplied nitrogen and extended the season of living cover. Unmanaged forests and fields leached little or no nitrate. Plant Pests and their Enemies. The soybean aphid (Aphis glycines), an invasive insect pest, is the greatest threat to soybean production in the United States. First detected in the United States in 2000, this East Asian pest has spread rapidly through the Midwest and costs growers about $30 million to $50 million per year in reduced yield. By 2005, farmers had responded with a 20-fold increase in insecticide use, spraying millions of acres of soybeans that formerly went untreated -- at costs of about $10 per acre. Long-term study of ladybird beetles at KBS had documented their importance as predators of other aphids in wheat, poplar, and other crops. In 2002, we detected the arrival of Harmonia axyridis, an Asian species of ladybird beetle new to the US. Using experiments in which fine-mesh cages were used to keep predators away from soybean plants, we have shown that ladybird beetles could keep aphids below economic thresholds: inside the cages aphid populations quickly built to levels that would otherwise justify spraying. Outside the cages ladybird beetles kept aphid populations low late into the growing season -- but only where there was sufficient natural habitat in the landscape to provide food and shelter for the predators throughout the year. Economic analysis showed that in 2008 ladybird predation provided biocontrol equivalent to $13-$79 per acre in reduced pesticide use and averted yield loss. The value of this natural biological control of the aphid in four states (Iowa, Michigan, Minnesota, and Wisconsin) was at least $239 million per year.
