Monday, November 13, 2006 - 1:30 PM

Nitrous Oxide Emissions from a Potato-Barley-Red Clover Rotation as Influenced by Nitrogen Source and Timing of Application.

David Burton1, Balakumar Thangaraj1, John A. MacLeod2, and Bernie Zebarth3. (1) Nova Scotia Agric. College, Truro, NS B2N 5E3, Canada, (2) Agriculture and AgriFood Canada, Crops and Livestock Research Center, AAFC, 440 University Ave, Charlottetown, PE C1A 4N6, Canada, (3) Agriculture & Agri-food Canada, P.O. Box 20280, Fredericton, NB E3B 4Z7, CANADA

There is increased concern over N2O emissions from arable crops such as potato (Solanum tuberosum L.) which receive high fertilizer N inputs. This study examined the effect of various nitrogen sources (NH4NO3, solid and liquid swine manure) and times of application (spring vs fall) on N2O emissions from all phases of a potato-barley-red clover rotation. All nitrogen sources were applied at a rate sufficient to supply 120 kg N ha-1 to the crop.  Nitrous oxide flux measurements were taken over the entire year, with primary focus on the non-frozen period, using non-steady-state vented chambers.  Results indicated that the majority of emissions were associated with fertilizer application prior to the potato phase of the rotation.  Much lower emissions were seen in the barley and red clover phases of the rotation.  There were no significant differences between the N sources examined and while fall applied manure tended to result in higher emissions than spring-applied manure, these differences were not significant when considered over the entire year.  When examining the three years of the rotation, emissions were lower than would be predicted using the IPCC coefficient.