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Long Term Ecological Assessment of Low Energy Farming Systems (LEAFS)

Principal Investigators: Kenneth Mulder, Ben Dube
Funding: $233,000

The modern history of agriculture can be characterized by a steady process of replacing land and labor as resources into food production with energy in the form of fossil fuels. All three resources are substitutable:

  • Energy enables production with less land by using fossil-derived nutrient resources such as captured nitrogen in urea fertilizers and mined minerals like phosphorous.

  • Energy enables production with less labor through the use of fossil-powered machinery.

  • Labor can substitute for land usage through increased human management and the use of human-powered technologies.

  • Conversely, wider plant spacing enables more efficient labor usage but results in lower yields.

Currently, humankind is growing more food on less land and with less labor than ever before, but at a significant cost in terms of fossil fuels as well as carbon loading. Indeed, modern agriculture uses more energy to produce food than is found in the food produced. As concerns grow regarding energy supplies and climate change, there is growing interest in understanding the potential trade-offs in low-energy production systems. Humankind can grow food without fossil fuels, but what are the costs in terms of land and labor? How can modern developments in human and animal powered farm technologies influence these tradeoffs? And how important is the development of the underlying agroecosystems that support these production systems?

In order to investigate these questions, GMC, through the generous support of the Yavanna Foundation, has initiated a unique research program assessing the viability of three energy-efficient vegetable production systems, two of them—human-powered and draft-animal-powered—being fossil-fuel-free. The Long-Term Ecological Assessment of Farming Systems (LEAFS) research project aims to manage these three systems for a minimum of ten years and collect data assessing:

  • Land utilization—How much land is required to support the system, including land needed to feed draft animals used on the farm and land used to produce nutrients.

  • Labor productivity—How much human labor is required to support the system including production labor as well as support labor (e.g. care of draft animals).

  • Energy requirements—How much energy goes into the system, including fossil fuels, metabolic energy (animal and human), and embodied energy (machinery, compost, biological insecticides, etc.)

  • The role of soil ecosystems in enabling production with low energy and nutrient inputs in human and animal powered systems.

  • These three vegetable production systems and their hypothesized strengths and weaknesses are as follows:

    Human-powered, low-input bio-intensive: Four vegetable plots are managed completely with human power with the only outside nutrient inputs being potting soil associated with transplants and leaf litter for mulch. Beds are permanent allowing for a high degree of soil ecosystem development. Highly developed human-powered vegetable production technologies are utilized to maximize productivity. One-fifth of the growing space is in cover crops due to the very low nutrient inputs. However, human-scale technologies enable up to three times the planting density. With no purchased inputs, this system is nearly fossil fuel free. This is the treatment that will require the longest time to develop because of its high reliance on the soil ecosystem for nutrient supply.

    Energy inputs: Low. Fossil inputs: Nearly zero. Land use: Very low, except no purchased inputs will likely reduce yields. Labor input: Very high, especially during establishment.

    Oxen-powered, low-input bio-extensive: One half acre plot is powered by a team of oxen using a mixture of old and new technologies. Oxen-power is used for primary and secondary tillage, cultivation, manure spreading, cover crop seeding, and some harvesting. Oxen also supply the power for hay production to feed themselves. This system uses less labor for production than the human-powered system, although animal care and training take significant time. For nutrient management, the system relies on manure from hay feeding as well as being planted to a full-season cover-crop once every three years. Both of these factors, as well as pasture needs and the wide-spaced single rows, significantly increase land requirements. The only major fossil-fuel inputs are for new animal equipment.

    Energy inputs: Medium due to oxen energy. Fossil inputs: Nearly zero. Land use: High because of cover crops, hay field and pasture. Labor input: Medium and more spread out over the year due to animal care needs.

    “Conventional” small-scale organic: Four plots are managed in a manner that simulates many small-scale organic vegetable growers in the Northeast. This system utilizes an 11-hp walking tractor for power for tillage and cultivation and also purchases organically approved inputs such as compost, row covers, and biological insecticides. Wide row spacing optimize usage of the walking tractor but increase land requirements. Purchased inputs guarantee optimal soil fertility. Cover crops are utilized as feasible and needed.

    Energy inputs: Medium to high, both direct and embodied in compost and other inputs. Fossil inputs: Medium. Land use: Medium because of wide spacing for tractor. Labor input: Low to medium

    All three systems will be compared against aggregate data for US vegetable production energy use, labor productivity, and energy efficiency.

    A full time research and production assistant has been hired to oversee data collection and funding has been used to increase the college’s draft-animal and human-powered infrastructure.

    Download report here (PDF)

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