Sensitivity analysis for nitrogen inputs, nitrogen outputs, and changes in biofuel crop acreages for predicting residual soil nitrogen and nitrate leaching in Canadian agricultural soils

Substantial improvements have been made to the Canadian Agricultural Nitrogen Budget model (CANB) for estimating residual soil nitrogen (RSN) and the indicator of the risk of water contamination by nitrogen (IROWC-N). These included new algorithms for manure, fertilizer and biological fixation inputs and losses as well as the incorporation of a versatile soil moisture model. The new semi-dynamic model (CANB v 3.0) was compared to the static model (CANB 2.0) for estimating both RSN and IROWC-N. Sensitivity analysis of the RSN component using 2006 land use practices was also conducted and crop yield and N uptake were found to be the most sensitive parameters, followed by biological N2 fixation and the addition of fertilizer N and manure N. Land use scenarios were evaluated to examine if increasing the proportion of biofuel crops grown in Canada would change RSN and IROWC-N appreciably. The analyses demonstrated that the area of canola and maize crops could be increased in Canada by up to 40% to meet biofuel production demands without significantly changing RSN and IROWC-N.