Small
organic farms growing food and biofuel crops:
Effects of scale on sustainability
  |
| Study conducted by Michael Bomford and Tony Silvernail in cooperation with the Post Carbon Institute, with funds from the United States Department of Agriculture |
Summary
US
biofuel production has increased by 400% in the past
decade, driven by government policy intended to reduce dependence on
imported fossil fuel and mitigate greenhouse gas emissions. Most US
biofuel plants use corn as a feedstock, grown in monoculture on
large-scale industrial farms. This offers little net energy advantage
over fossil fuel use, and raises concerns about environmental
sustainability. This project examines the sustainability of alternative
biofuel crops, grown organically at scales ranging from production with
hand tools to conventional tractor-based production. Energy, land, and
labor-use efficiency will be compared across crops and farm scales. The
effect of land, labor, and energy prices on small farm profitability
will be compared for food and biofuel production at a range of small
farm scales.
Objectives
- Compare sustainability of food and biofuel feedstock production on small organic farms representing three production scales.
- Compare sustainability of corn, soybean, sweet sorghum, and sweet potato food and biofuel feedstock crops grown in small farm systems.
- Determine market price thresholds at which feedstock production becomes more profitable than food production for each system.
- Compare resource-use efficiency of research plots to that of working organic farms operating at each of the scales studied.
Approach
Food and biofuel varieties of
corn, sweet potato, sweet sorghum, and soybean will be rotated through
three small organic farming systems, representing three scales of
agricultural production:
- hand tools only;
- no tools larger than a walk-behind tractor; and
- management conducted primarily with conventional four-wheeled tractors.
Treatments will be replicated four times in a randomized complete block design. All crops will be grown in each system in each of four study years. Soil samples will be collected from each plot twice each study year and analyzed for organic matter content, cation exchange capacity, electrical conductivity, active carbon fraction, and microbial enzyme activity.
- Labor, land and energy inputs required for system establishment, maintenance, and harvest will be recorded for each system.
- Embodied energy estimates will be calculated for each input consumed, based on published estimates and techniques.
Yields will be recorded for each variety, crop,
and system.
The carbohydrate content of the harvested portions of the biofuel
feedstock varieties will be measured to determine their potential for
ethanol production. - Farmers market and commodity market prices will be recorded for each food crop at harvest.
- Land, labor, and energy efficiency index values will be calculated for each crop and system by dividing marketable harvest by the recorded inputs.
- Energy balances will be calculated for each system by dividing the energy output from harvest by the energy input required for system establishment and maintenance.
- System profitability will be calculated by subtracting the sum of fixed and variable production costs from the value of the marketable harvest.
Marketable harvest value will
be calculated differently for
each system, according to assumptions about the goals of each
system. - An economic model will be constructed that includes energy, labor, land, and organic crop prices.
- A range of possible future values for each factor will be tested, to examine the effect of possible price scenarios on farmer decision-making.
- On-farm demonstrations will be conducted on working organic farms representing each of the three system scales in Kentucky and California. Each farmer-cooperator will grow at least one of the crops considered in this study, and will maintain complete input and marketable yield records for that crop. On-farm demonstrations will serve to relate conclusions drawn from this study to real world conditions, and facilitate direct knowledge transfer to working farms.
Last updated January 31, 2007
