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Ability of yard trimmings compost to mitigate environmental impacts of over-winter field stored poultry litter

University of British Columbia

Incorporation of poultry litter (PL) into crop production on British Columbia's Fraser River delta is an important means of recycling this over-abundant agricultural waste product. However, environmental and ecological concerns associated with overwinter field storage of PL should be addressed. To mitigate these concerns some farmers have been storing the PL on a 30 cm thick base pad of City of Vancouver yard trimmings compost (YTC) and further covering the pile with a 15 cm thick layer of YTC . A column study was conducted on the UBC, Vancouver campus to assess the effects of the YTC base pad and cover on the quality of leachate emanating from the PL. The YTC layer under the PL decreased (P<0.05) the cumulative Cu , Zn and P leached as compared to the PL alone by 50%, 54% and 30%, but had little ability to retain N or soluble salts. Concentrations in the first flush of leachate out of the P L were reduced by the YTC pad from 25 to 1.3 mg Cu L⁻¹, 11 to 0.95 mg Zn L⁻¹, and 430 to 40 mg PL⁻¹. A key finding was that the YTC cover increased (P<0.05) the leaching o f N, Cu and Zn from the underlying PL . A complementary field study was conducted over the same winter in Delta, BC . Three PL storage piles were constructed with and without an YTC pad and/or YTC cover. Soil samples from under and around the piles (0-15 and 15-30cm depths) as well as samples from the YTC base pad were analyzed. Crop development the following spring was negatively impacted under all piles. The YTC pad protected the soil below the core of the pile from leaching due to water table rise however it was less effective under the highly leached outer regions of the piles. Delta farmers are advised to not store PL directly on the soil and to consider the use of an YTC base pad thicker than 30cm. The YTC cover apparently increases leaching, likely due to increased infiltration of precipitation, yet it reduces run-off, and isolates the PL from wildlife.

Text

2011-03-04

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http://hdl.handle.net/2429/32061

Soil Science

University of British Columbia

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