CEFS Long-Term Systems Research: Providing the Building Blocks for Resilient Food Production Systems

Learning Outcomes

A project focused on characterizing greenhouse gas emissions from conventional and organic farming practices is highlighted here as an example of key learning outcomes. 

Nitrous oxide (N₂O) fluxes from soil are considered a significant source of greenhouse gas emissions from land-based agricultural activities.  Nitrous oxide is ~300 times more potent a greenhouse gas as carbon dioxide (CO₂).  Nitrogen availability in soil is a key factor in how much N2O emission might occur.  Nitrogen is often a key limiting factor in organic production systems due to the need for mineralization of organic compounds before becoming available for plant uptake.  Poor synchrony between release of organic N and the critical period of plant N uptake demand can lead to excessive N availability during some parts of the year, and therefore, potentially large fluxes of N₂O loss to the atmosphere.  This study characterized N₂O emissions between conventional and organic corn production systems using different methods of N₂O flux detection. 

Soil N₂O emissions have been and continue to be measured during the corn growing season in both (1) conventional, no-till management and (2) organic management systems using a combination of automated and static chambers.

Nitrous oxide fluxes are driven largely by rainfall events in coordination with N fertilizer applications (planting and side-dress).  However, in some instances there is emission with small rainfall events later in the growing season, as well as an apparent consistent background level of emissions.  These short term events are very transient in nature and dissipate before measurements with the static chambers would be possible unless teams were constantly on site.

To date, cumulative emissions estimated using static chambers and USDA-GRACEnet protocols appear to be underestimating N₂O emissions by a substantial margin.  However, interpretation and obtaining quantitative measurements from the automated chambers over the larger areas we incorporate in our studies is still one of the primary objectives of our research.

We are now in contact and seeking further cooperation with researchers in Canada and Denmark who are also employing automated and static chambers in their efforts to quantify gas emissions from soils in various management systems.  A new faculty member, Dr. Alex Woodley who will be assuming responsibilities for continued measurements of N₂O emissions in our group, has obtained funds to visit collaborators in Demark in the spring of 2020 to promote and further our cooperative effort.

We have been successful in establishing remote access to our data logging computer to be able to check the status of soil N₂O fluxes with our automated system.  This has substantially improved the efficiency of our static chamber measurement efforts both in timing and intensity of an event.  The online system provides immediate feedback as well to other members of the group, e.g. who desire to soil sample after a major event to monitor soil microbial population dynamics.

We are actively building upon the base made possible by SARE funds to obtain other funding and expand our presence and measurement capabilities on site.  We have been able to double the number of automatic chambers we have, and we are now planning to enhance our instrument trailer on site to accommodate more equipment.  The continued support from SARE is critical to this effort providing a needed foundation to maximize use of other one-time funds.

We have hosted several groups at the site, including the Nature Conservancy, Environmental Defense Fund, Kellogg Foundation, and the Southern SARE Council.  In addition, classes from NC State’s agroecology program have toured the site to discuss N management in conventional and organic systems.  This funding has supported summer research assistants from NC State to work on this project, providing training and experience in agriculture and environmental research.

Project Outcomes

A project focused on organic grower perceptions is highlighted here as one of the key project outcomes.  Other more technical outcomes are being revealed in projects on soil health conditions and weed population dynamics of long-term farming practices, as well as greenhouse gas emission rates from conventional and organic farming practices.

A survey of organic growers in North Carolina led to improvement in our knowledge of the social constraints facing farmers.  A total of 18 farmers was interviewed.  All of the farmers were white men in the Piedmont and Coastal Plain regions.  They have all been certified organic at one point in time.  However, at the time of the interviews, only 15 out of 18 farmers were certified organic.  

Although all of the farmers grew organic grains, their primary farm products varied.  The reasons the farmers maintained organic certification were linked to personal values, better health of people and livestock, and the value-added benefit of marketing organic goods.  Many also cited how the higher prices on the organic market helped them to maintain production at a smaller scale.  Among those who dropped certification, sometimes the added value was not enough to offset the increased cost of labor and the frustrations of organic weed management.  One farmer viewed organic practices as less sustainable on his land (he preferred a no-till approach) and thought tilling soil for weed control was “excessive” and damaged soil health.  The certification process was manageable, but time-consuming for several farmers, but one mitigation strategy for this was to hire someone to handle all of the paperwork.

Although the grain farmers in this study did not cite land tenure as a reason for dropping or maintaining organic certification, they did note that leased land creates challenges related to decision-making on expensive infrastructure or land improvements such as drainage tiles, irrigation ponds, or land smoothing.  Without a long-term lease or landlord buy-in, these improvements did not seem worth it, and could even result in land-loss from other farmers outbidding them on rent for the more desirable, improved farmland.  Additionally, the ways in which farmers acquire and keep farmland revealed unexpected strategies, such as raising one’s own rent, renting land and not farming it, or putting family land in a conservation easement to resist development pressures in growing areas.  Several farmers were not concerned about maintaining their land leases, especially if they were not close to growing urban areas and felt trusting of their fellow community members to not “steal” the land from under them by outbidding the rent.

Farmer interviews revealed that growers are feeling some anxiety about leased land, and some are facing the reality of farming on fewer acres.  By employing organic as a strategy to make money on less land, farmers are able to maintain a livelihood.  However, concerns about losing leased land – either to the highest bidder or to development pressure – influenced decisions like raising their own rent, renting more land than they farmed, or holding off on infrastructure projects.