Nitrous oxide emissions and productivity of irrigated potato: Effects of nitrogen fertilization options
Shakila K. Thilakarathna, Michele Konschuh, Shelley A. Woods, Guillermo Hernandez‐Ramirez
Abstract
Abstract Improved N management is needed in intensive agriculture to mitigate nitrous oxide (N 2 O) emissions while sustaining high yields. We assessed the effectiveness of polymer‐coated urea (PCU); nitrification inhibitor 2,4‐dimethylpyrazol succinic acid (DMPSA), a biostimulant; and their combinations with granular urea and ammonium sulfate nitrate (ASN) fertilizers to reduce N 2 O emissions and to improve potato ( Solanum tuberosum L.) productivity under irrigation. Sites were located in Lethbridge and Brooks, Alberta, Canada over two growing seasons. Tuber yield, grade, specific gravity, and N uptake were quantified. We used the chamber method to measure N 2 O fluxes from potato hills and furrows. The N 2 O emissions from furrow positions were at least two‐fold greater than those from hills at the Lethbridge site. Peak N 2 O emissions and increased N concentrations in potato petiole and soils occurred shortly after fertilizer applications. The overall average emission factor (EF) of N 2 O was 0.056% kg N 2 O–N kg −1 N fertilizer (accounting for emissions from unfertilized controls). Urea alone commonly exhibited the highest N 2 O fluxes. Admixing DMPSA with either urea or ASN lowered N 2 O emissions in only certain cases. For instance, in one growing season at the Brooks site, adding DMPSA to urea reduced the N 2 O emissions by 57%. Likewise, in one of the four site‐years in the study, 36% higher potato marketable yields were obtained when applying either ASN treated with DMPSA or PCU compared with the unfertilized controls (45 vs. 33 Mg ha −1 ). Results showed that under specific conditions, N application strategies using DMPSA admixed with either urea or ASN can maintain high potato yields while reducing N 2 O emissions relative to soils receiving these fertilizers without this additive.