Analysis of N-Species (NO3-, NO2-, AND NH4+) in Canadian Marginal Land Soils for Growing Sorghum Biomass

As part of a project to develop low-cost and high production systems for growing sorghum biomass on marginal lands in Canada, this research focuses on analysis of inorganic nitrogen species (NO₃^-, NO₂^-, and NH₄⁺) in soil samples collected from 3 selected fields in Ontario. Soil samples were extracted using an acidified water solution and analyzed using colorimetric methods. Evaluation of NO₃^- established comparable levels of plant-available N between marginal and agricultural soil, prior to sorghum planting. Comparison of soil from plots of 3 different sorghum hybrids showed no significant influence from hybrid on soil NO₃^-. Application of N fertilizer influenced soil NO₃^- levels, but the response differed between marginal sites, as well as in comparison to the agricultural field. At marginal sites, N fertilizer at the applied rate of 45 kg N ha^-1, had no significant impact on sorghum biomass, yet appears sustainable in terms of maintaining available N levels.