Reducing energy requirements and closing the carbon and nitrogen cycles at the UNH Organic Dairy Research Farm through on-farm bedding production and aerobic static pile composting

Matt Smith and Dr. John Aber

Matt SmithUniversity of New Hampshirems7@wildcats.unh.eduAberlab.net603-285-5197

Contact

Project Goal: A more closed agroecosystem• Reduced carbon and nitrogen footprints• Produce bedding from farm woodlots

• Eliminate long-distance delivery• Sell shavings to other UNH research farms

• Improved manure management• Aerobic static pile (ASP) composting with thermal

energy capture• Eliminate odors and methane emissions• Reduce volume of material to be spread on farm

fields, saving fuel and transport costs• Produce more stable product less prone to leaching

Project Summary

Used bedded-pack, manure, hay, and woodchips, are combined in a specific “compost recipe” and loaded into the ASP composting facility with a manure spreader

• Current recipe: 4 yd3 used bedded pack, 2 yd3 manure, 2 yd3 hay, and 2 yd3 woodchips per 10 yd3 batch, with 20-25 batches per bay (200-250 yd3 per bay per month)

Research Note: Trials on optimal compost recipes for heat production are capture are underway

Phase 1: Harvest Trees for Bedding

Use wood shavings on the three bedded-packs and in the calf hutches • Bedded-packs top-dressed twice a week with bedding,

and cleaned out twice a year (May and October)

Phase 3: Use Shavings for the Farm Bedded-Packs

Phase 6: Compost is Spread on Farm Hayfields

Phase 7: Future Work Reducing C and N Footprints

Phase 4: Compost Farm Wastes in the ASP Facility

Phase 2: Produce Animal Bedding

Annual harvest of 1-2 acres from 160 acre farm woodlot• Yields 60 cords of eastern white

pine/year• Equals the farm’s annual bedding

requirement of 700 yd3 of shavings

Shave 8 ft eastern white pine logs with a wood-shaving machine

• Machine produces 12-20 yd3 of wood shavings/hour

• Only softwoods are suitable for bedding - contain resins toxic to disease-causing microbes (Godden et al. 2008). Also easier to shave.

Phase 5: Heat Recovery from CompostHeat is produced from microbes under an aerobic composting environment • Microbes receive oxygen through a fan system that

pulls oxygen through the pile, while pulling heated compost vapor out of the pile

• Heated vapor (130-160oF) is sent into Agrilab’s Compost Heat Recovery System to warm a 295 gallon tank of water to 100-120oF for farm hot water needs

Research Note: Trials on heat production/capture through manipulation of aeration, irrigation, nutrient addition, and compost covers, are underway. Economics of the entire heat-recovery system are ongoing

Project Supported By:

Compost spread following 90-120 days in the ASP facility• Compost may be sold in the

future to reduce farm N and P footprints and also generate revenue for future research

ReferencesGodden, S., Bey, R., Lorch, K., Farnsworth, R., and Rapnicki, P. 2008. Ability of organic and inorganic bedding materials to promote growth of environmental bacteria. J. Dairy Sci., 9, 151-159.

Smith, M. and Aber, J. 2014. Heat recovery from compost. BioCycle, 55(2), 27.

Research Note: Trials comparing eastern white pine v. eastern hemlock as bedding source are underway. The economics of an on-farm bedding production operation are also being analyzed.

C-footprint reductions from CO2 scrubbing of the compost exhaust stream by plants in a high tunnel attached to the composting facility.

N-footprint reductions from NH3 and N2O scrubbing of the compost exhaust stream from a woodchip/compost biofilter attached to the composting facility.