Hyatt, Charles R.2011-05-192011-05-192011-04https://hdl.handle.net/11299/104614University of Minnesota M.S. thesis. April 2011. Major: Plant Biology. Advisor: Rodney T. Venterea. 1 computer file (PDF); viii, 154 pages.Irrigated potato (Solanum tuberosum L.) production requires significant inputs of fertilizer N for optimal tuber yield and quality. However, high N rates carry the risk of high N loss, particularly in coarse-textured, well-drained soils where potatoes are commonly grown. Polymer coated controlled-release ureas (PCU) have shown promise in reducing NO3 - leaching, a groundwater quality concern, and may potentially also reduce emissions of N2O, a greenhouse gas with nearly 300 times the warming potential of carbon dioxide. However, comparisons of multiple PCUs are uncommon. Studies were conducted over three years to compare N loss (as NO3 - and N2O), yield response, and N use efficiency (NUE) from an unfertilized control, split applied conventional N fertilizer (CSA), and two PCU products (PCU-1 and PCU-2) applied at 270 kg N ha-1 yr-1. Tuber yields, NUE, and leaching did not differ among fertilized treatments. Directly measured N2O emissions were significantly lower with PCU-1 than CSA. Fertilizer induced emissions were relatively low, ranging from 0.10 to 0.49% of applied N. Indirect N2O emissions, estimated using the IPCC default emission factor of 0.75% of NO3 - leached, were significantly lower than direct emissions. However, due to uncertainty, indirect emissions could be anywhere from 0.6 to 84.9% of direct. These results show that PCU can potentially reduce N2O emissions. However, results are product specific and work remains to be done in narrowing the indirect emission factor uncertainty range.en-USPlant BiologyThesis or Dissertation