Long-Term Ecological Assessment of Farming Systems (LEAFS): Comparing Human, Animal, and Small Machine Power for Fresh-Market Horticulture

In order to assess the potential for human and animal power and related fertility management systems to reduce the demand for energy fossil fuels in agricultural production, we report findings from the first 2 years of the Long-Term Ecological Assessment of Farming Systems (LEAFS) at Green Mountain College in Poultney, VT, USA. LEAFS compares three small-scale, diverse vegetable production systems, one powered by human labor, one by draft animal power, and one by small engine power. Data was collected on all inputs including land usage, labor, and direct and indirect energy consumption. Yield of crops was measured and converted into energetic and economic output. This data was used to calculate efficiency statistics including energy and financial returns on land, labor, and energy invested. The draft animal and machine power systems were comparable in the financial returns to labor while the human system yielded approximately 25% less in this regard. The human and draft animal systems had equal energy returns to energy invested of 1.21, a high rate of efficiency for vegetable production. The machine system was net energy negative but efficient compared to conventional production. Data from all three systems suggests factor substitution of both labor and land for energy.