Volume 65, November 2016, Pages 432–442
- Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, University of Gävle, Kungsbäcksvägen 47, SE-801 76 Gävle, Sweden
- Received 28 October 2015, Revised 3 June 2016, Accepted 26 June 2016, Available online 21 July 2016
Abstract
Keeping
horses causes environmental impacts through the whole chain from feed
production to manure. According to national statistics, the number of
horses in Sweden is currently 360,000 and is continuing to increase.
This result in increasing amounts of horse manure that has to be managed
and treated, which is currently done using practices that cause local,
regional, and global environmental impacts. However, horse manure and
its content of nutrients and organic material could be a useful
fertiliser for arable land and a substrate for renewable energy
production as biogas. The aim of the paper is to identify and describe
potentially critical factors in horse keeping determining the amount
(total mass) and characteristics (nutrient content and biodegradability)
of horse manure, and thus the potential for anaerobic digestion. A
systematic combining approach is used as a structural framework for
reviewed relevant literature. All factors identified are expressed as
discrete choices available to the horse keeper. In all, 12 different
factors were identified: type and amount of feed, type and amount of
bedding, mucking out regime, residence time outdoors, storage type and
residence time of manure in storage, spreading and soil conditions, and
transport distance and type of vehicle fuel used. Managing horses in
terms of these factors is of vital importance in reducing the direct
environmental impacts from horse keeping and in making horse manure
attractive as a substrate for anaerobic digestion. The results are also
relevant to environmental systems analysis, where numerical calculations
are employed and different biogas system set-ups are compared to
current and other treatments. In such assessments, the relevance and
importance of the critical factors identified here and corresponding
conditions can be examined and the most promising system set-up can be
devised.
Keywords
- Horse manure;
- Horse keeping;
- Anaerobic digestion;
- Nutrient recycling;
- Systems perspective
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