Scale & sustainability of organic farms growing food and biofuel crops

Summary

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 are compared across crops and farm scales. The effect of land, labor, and energy prices on small farm profitability are compared for food and biofuel production at different small farm scales.

Objectives

1. Calculate land, labor, and energy efficiency of food and biofuel feedstock production on small organic farms representing three production scales. 
2. Compare sustainability of corn, soybean, sweet sorghum, and sweet potato food and biofuel feedstock crops grown in small farm systems. 
3. Determine market price thresholds at which feedstock production becomes more profitable than food production for each system. 
4. 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 are rotated through organic farming systems representing three scales of agricultural production: 

1. hand tools only; 
2. no tools larger than a walk-behind tractor; and 
3. management conducted primarily with conventional four-wheeled tractors.
   

Treatments are replicated four times in a randomized complete block design. All crops are grown in each system in each of four study years.

• Labor, land and energy inputs required for system establishment, maintenance, and harvest are recorded for each system. 
• Embodied energy estimates are calculated for each input consumed, based on published estimates and techniques. 
• Yields are recorded for each variety, crop, and system. The carbohydrate content of the harvested portions of the biofuel feedstock varieties is measured to determine their potential for ethanol production. 
• Land, labor, and energy efficiency index values are calculated for each crop and system by dividing marketable harvest by the recorded inputs. 
• Energy balance is calculated for each system by dividing the energy output from harvest by the energy input required for system establishment and maintenance.
  

Preliminary results are posted at the Energy Farms blog.

Updated 06/18/10