Social Dimensions of Soil Carbon Dynamics

Harris, C.K. and L.S. Bohannan

Presented at the All Scientist Meeting (1998-07-21 to 1998-07-22 )

Our research goal was to gain an understanding of the social and economic factors that contribute to the spatial and temporal variation in the soil carbon dynamics of agricultural ecosystems in the U.S. Midwest. Our working hypothesis was that soil carbon dynamics are affected by 1) social and economic structure and 2) agronomic management (see figure one).Through visual surveys, and mail and telephone surveys, the row crop operators in the four townships surrounding the KBS LTER were identified. Preliminary data on social and economic structure and agronomic management was collected from the row crop operators.Our first hypothesis was that growers use relatively simple management heuristics for making agronomic decisions. The data collected did not uphold this hypothesis. The management heuristic for each farm varied in its level of complexity, as well as in its form. This made the process of grouping farms by similar inputs, tillage systems and cropping sequences impossible and matching farms to the different treatment protocols at the LTER problematic.Our second hypothesis was that farmers manage all of their acreage using the same management regime or heuristic. Our results found this to not be so. The farmers managed their acreage using different heuristics for different fields at the same time. The heuristics included: 1) biophysical factors such as the differing slopes, soil textures and orientations of different fields; 2) organizational factors such as institutional pressures and rewards; 3) cultural factors such as personal beliefs and values; 4) population factors such as migration patterns and changes in population densities around the individual fields; and 5) technological factors such as the types of machinery, seed, fertilizers, and pesticides available for use, and the time, knowledge and economic resources necessary to utilize a technology.Our third hypothesis was that farmers manage a field following a consistent management scheme over time. Even this was shown not to be consistent. Individual fields were managed differently over time for a variety of reasons. These reasons were sorted into five categories. The first category is biophysical factors such as annual variation in the climate (temperature, precipitation), and the type and pressure of weeds the past season. The second category includes demographic changes such as aging, health, and family structural changes such as the birth or death of a family member or divorce. The third category, organizational changes, includes changes such as new markets, changes in land tenure, and/or incorporation of the farm operation. The fourth category, changing cultural pressures, includes educational changes. The last category, technological changes, includes changes in crop needs.On the basis of these results, we are gathering information that will allow us to further understand the factors that are influencing the operators’ attitudes and behavior, and to build a model of the farm operators’ decision-making process.Return to Contents

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