NEPC 2013 Annual Meeting: Bedding

Matt Smith, University of New Hampshire, reporting for John Aber
Reducing Costs for Bedding and Energy on Organic Dairy Farms

Matt Smith presented the last research project currently underway in the Northeast Region related to pasture-based farming. Matt is a doctoral student under Dr. John Aber in the Natural Resources & Earth Systems Department at UNH.

Matt and John are looking at the feasibility of using softwood wood shavings as bedding material for organic dairy cows and as an energy source when it is composted after it is too soiled for continued use as bedding. UNH had met with organic producers and farmers to determine areas of research need. The conclusion of the meeting was primarily that organic farmers require lower input costs, such as feed, energy, and bedding. Therefore, this research project directed its attention to energy and bedding since the Brito and Bosworth research was directed towards the feed issue.

This research project has two phases:

  • Phase 1 – Produce bedding from on-farm woodlot (reducing carbon and nitrogen imports/saves money).
    • Major component – Develop a shaving model for farmers to use looking at the economic feasibility of shaving one’s own wood from the farm woodlot.
  • Phase 2 – Use spent animal bedding (high carbon), and mix with manure (high nitrogen), to produce optimal compost mix while stabilizing the nitrogen so it is not lost to the atmosphere as a GHG.

White pine wood shavings are comfortable for cows to lie down on. However, commercially available sources of kiln dried white pine shavings cost the UNH Organic Dairy Farm annually $74,000-$85,000. The solution to reduce cost of bedding at the UNH Organic Dairy was to produce bedding from on-farm sources (160 acre woodlot) with a shaving machine. This machine uses 4′ or 8′ logs 2-24″ in diameter “shaving log”. Only softwoods can be used (hardwoods not suitable bedding).

Most likely bedding source and highest grade is eastern white pine. The cost to do it yourself with your own wood source is $60,000 – a yearly savings in shavings of $14,000 to $25,000. Air-dried wood shavings are approximately 20% moisture. Kiln dried moisture is at 12% and is ideal, but requires energy to be dried and more costly due to drying and shipping costs.

This phase’s accomplishments so far are:

  • Built “On-farm animal bedding production model”
    • Allows for quick analysis of whether it is economical for a farmer (or institution) to purchase a shaving machine – justified UNH Organic Dairy Farm purchase
  • Harvested 1 acre to feed UNH shaving machine
  • Completed stem-analysis on 50 harvested eastern white pine trees.

Continued research contemplated is:

  • Purchase shaving machine and test/refine model before it is released
  • Test eastern white pine against eastern hemlock as a bedding source (microbial counts, cost of shaving, cow comfort, etc.)
  • Test various low-cost methods of drying bedding – kiln driers are at least $50,000 (not economical for small farmer)
  • Develop a “cookbook” on growing pine for the purpose of producing animal bedding (underway and close to finished).

The second phase of the research project is analyzing the feasibility of an on-farm heat-recovery composting facility. The facility being operated by the project was donated to UNH by private donor. The goal of the facility is to prove heat-recovery technology, and to see whether it is economically feasible for small to mid-sized dairies in Northeast. The facility is only the 3rd in the world using this technology (only institution). It uses isobar heat pipe technology (fancy name for a giant heat exchanger). The heat exchanger produces hot water and helps moisten the compost for faster decomposition.

Research objectives to complete this phase of the project are:

  • Determine optimal recipe (CN, moisture, bulk density) to produce the most BTU’s over 120 day composting cycle
  • Determine optimal aeration intensity
  • Test to see if intermittent high-nitrogen charges increase heat output to justify time/cost
  • Test various compost covers to see if temperature increases enough to justify time/cost
  • Compare various feedstock mixing options (bucket method, manure spreader, grain mixer) on heat recovery
  • Too many more to mention, including greenhouse
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