Document Type

Article

Publication Date

1-1-2019

Abstract

Core Ideas: Application of urea led to higher N2O emissions than urea–ammonium nitrate in sugarcane. Residue retention led to higher N2O and CH4 emissions irrespective of N source. Both N source and residue management did not affect CO2 emissions. Sugarcane (Saccharum spp.) is a major row-crop in the southern United States with high rates of N-fertilizer application and unique harvest-residue management. A 2-yr field experiment was conducted to investigate different N-fertilizer effects (urea and urea ammonium nitrate, UAN) and harvest-residue managements (residue-retain, RR, and residue-burn, RB) on greenhouse gas (GHG) emissions from soils under sugarcane production. In 2012, a split-plot design experiment was conducted with residue managements as main-plots and N-sources as sub-plots. In 2013, two experiments were conducted to investigate UAN effect under RR and RB, and N-source effect under RB on GHG emissions. Nitrogen was applied at 135 and 157 kg ha‒1 in 2012 and 2013, respectively. Soil GHG emissions were monitored using a closed chamber method. Results showed the majority of N2O emissions occurred within 4 wk after N-application. Average N2O emissions from urea-treated plots were 1.43 to 1.67 times higher compared with UAN for 2 yr. Urea had a N2O emission factor of 3.52 and 4.45% under RB and RR, respectively, whereas UAN had 1.67 and 2.46% under the same residue management. Higher N2O emission under RR treatment was supported by 15 to 20% more water-filled pore space (WFPS) in soil than RB plots, which also increased CH4 emissions. Higher correlation was found between N2O emission and WFPS in 2012 compared with 2013 (r2 = 0.52 vs. 0.36) because a majority of the rainfall in 2012 was received within 3 wk following N application. Nitrogen sources had no effect on CH4 and CO2 emissions.

Publication Source (Journal or Book title)

Agrosystems, Geosciences and Environment

First Page

1

Last Page

10

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