Date of Award

Spring 2016

Project Type

Dissertation

Program or Major

Natural Resources and Environmental Studies

Degree Name

Doctor of Philosophy

First Advisor

John D Aber

Second Advisor

Mark J Ducey

Third Advisor

Theodore E Howard

Abstract

This study explored two innovative approaches to assist dairy farmers in reducing costs associated with animal bedding and waste accumulation on their farms. This was accomplished by finding value in underutilized farm resources and waste streams and recycling them back through the system, or converting them into revenue generating products to be exported off the farm. The University of New Hampshire Organic Dairy Research Farm was used as a case study for this agroecosystem project.

The first innovative approach was the production of animal bedding using a wood shaving machine and low-grade eastern white pine (Pinus strobus L) harvested from the farm’s woodlot. This approach was selected because a pre-study survey of 129 New England dairy farmers conducted as part of this research, indicated that bedding costs increased by 89% from 2003 – 2013. This substantial cost increase raised the obvious question, is there a possible cost saving alternative to outright purchasing of bedding material? After two years of using the wood shaving machine, a financial decision model was developed, allowing individuals to input operator-specific parameters to determine the feasibility of producing wood shavings at their site. Model output indicated that the average-sized organic or conventional dairy farm in New England would not have a favorable payback period, requiring up to 11 years to pay for the machine, if producing bedding for only on-farm consumption. Large farms, or a cooperative of smaller farms using a trailer-mounted machine were found to have the greatest likelihood of positive returns from this type of venture.

The second innovative approach involved the construction and operation of a novel composting system, capable of processing the farm’s wastes, while recovering thermal energy from the process for on-farm hot water heating. A detailed review of 45 compost heat recovery systems was used to assess which system to build at the UNH site. Based on this review, the aerated static pile (ASP) composting method with Agrilab Technologies’ heat exchange system was selected. During the construction phase of this facility, a detailed report on how to build an ASP heat recovery composting facility was developed for use by compost practitioners contemplating use of this technology. Upon completion of this facility, research trials began on heat extraction and greenhouse gas (GHG) mitigation potential of the system. Results indicated that the UNH system was capable of recovering 293,909 - 811,332 BTU/day with compost vapor temperatures in the 121 – 133°F range. With regard to fossil fuel offsetting, the compost heat exchange unit would reduce oil consumption by 911 – 2515 gallons per year. From a GHG mitigation standpoint, this is equivalent to an offset of 10 – 28 TCO2/yr.

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