Managing Global Resources for a Secure Future

2017 Annual Meeting | Oct. 22-25 | Tampa, FL

108984 Effects of Additives Applied with Urea on Nitrate Leaching and Potato Tuber Yield and N Uptake.

Poster Number 1339

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Nutrient Management and Environmental Quality General Poster (includes student competition)

Wednesday, October 25, 2017
Tampa Convention Center, East Exhibit Hall

Emerson de Freitas Cordova de Souza, Department of Soil, Water and Climate, University of Minnesota, St Paul, MN, Rodney T. Venterea, 439 Borlaug Hall, USDA-ARS, St. Paul, MN, Carl J. Rosen, Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN and Nils Berger, EurochemAgro GmbH, Mannheim, Germany
Abstract:
Typically grown in sandy soils, the potato has large nitrogen (N) and water requirements and a shallow root system, which result in a high potential for groundwater contamination by nitrate (NO3--N). We conducted a two-yr field experiment with irrigated potato grown in a Hubbard loamy sand to assess the effects of urea applied at 67% and 100% of the recommended N rate (RNR) with and without the addition of varying combinations of inhibitors and other amendments, including the nitrification inhibitors 3,4-dimethylpyrazol phosphate (DMPP) and dicyandiamide (DCD), the urease inhibitor N-(nbutyl) thiophosphoric triamide (NBPT), the N-fixing microorganisms (NFM) Azotobacter vinelandii and Clostrium pasteurianum, and the microbial enhancer (ME) L-amino acids, chitin, chitosan and glucosamine. Effects on growing season nitrate leaching, tuber yield, N uptake, and residual soil N concentration after harvest were evaluated. In the 2015 growing season, NO3--N leaching and residual soil N concentration were greater, while tuber yield and N uptake were less, compared to 2016. Tuber yield and N uptake increased with increasing N rate but were not affected by inhibitors and microbes or enhancers under the conditions of this study. In 2015, the combination of urea+DMPP+NBPT at 67% of RNR resulted in 13%, 23% and 25% less NO3--N leaching than urea alone, urea+DCD+NBPT, and urea+ NFM, respectively, while at 100% of RNR this combination resulted in the least NO3--N leached. In 2016, urea+DMPP+NBPT, urea+DCD+NBPT, NFM, and NFM+ME resulted in 44%, 60%, 51%, and 40% less NO3--N leaching compared to urea+DMPP at 67% of RNR, respectively, while urea+DCD and urea+DMPP+NBPT had 44% and 39% less NO3--N leaching than reported in urea alone at 100% of RNR, respectively. Conversely, the combination of urea+DCD+NBPT and urea+NFM at 67% of RNR resulted in 10% and 13% greater NO3--N leaching than urea alone in 2015, respectively, while at 100% of RNR, urea+DCD+NBPT and urea+NFM+ME resulted in 14% and 10% greater NO3--N leaching than urea alone, respectively. Overall, the results indicate that applying the dual inhibitors DMPP+NBPT with urea can be an effective strategy to reduce NO3--N leaching. The effect of NFM and ME was inconsistent, indicating that more research is needed to elucidate the effectiveness of these microorganism-enhancing additives for reducing N losses.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Nutrient Management and Environmental Quality General Poster (includes student competition)