Impacts of Enhanced‐Efficiency Nitrogen Fertilizers on Greenhouse Gas Emissions in a Coastal Plain Soil under Cotton

Abstract

Enhanced-efficiency N fertilizers (EENFs) have the potential to increase crop yield while decreasing soil N loss. However, the effect of EENFs on greenhouse gas (GHG) emissions from different agricultural systems is not well understood. Thus, studies from a variety of locations and cropping systems are needed to evaluate their impact. An experiment was initiated on a Coastal Plain soil under cotton ( L.) production for comparing EENFs to traditional sources. Nitrogen sources included urea, ammonia sulfate (AS), urea-ammonia sulfate (UAS), controlled-release, polymer-coated urea (Environmental Smart Nitrogen [ESN]), stabilized granular urea (SuperU), poultry litter (PL), poultry litter plus AgrotainPlus (PLA), and an unfertilized control. Carbon dioxide (CO), nitrous oxide (NO), and methane (CH) fluxes were monitored regularly after fertilization through harvest from 2009 to 2011 using a closed-chamber method. Poultry litter and PLA had higher CO flux than other N treatments, while ESN and SU were generally lowest following fertilization. Nitrous oxide fluxes were highly variable and rarely affected by N treatments; PL and PLA were higher but only during the few samplings in 2010 and 2011. Methane fluxes were higher in 2009 (wet year) than 2010 or 2011, and N treatments had minimal impact. Global warming potential (GWP), calculated from cumulative GHG fluxes, was highest with PL and PLA and lowest for control, UAS, ESN, and SU. Results suggest that PL application to cotton increases GHG flux, but GHG flux reductions from EENFs were infrequently different from standard inorganic fertilizers, suggesting their higher cost may render them presently impractical.

Emission factors for estimating fertiliser-induced nitrous oxide emissions from clay soils in Australia’s irrigated cotton industry

“…The latter value is at the upper level of N 2 O emissions from the limited amount of data available for irrigated cotton reported from other countries (Mahmood et al 2008;Scheer et al 2008;Liu et al 2010;Watts et al 2015) and of a similar magnitude to that reported by Grace et al (2004) at the same site. Scheer et al (2008) reported a comparable response to N in irrigated cotton in Uzbekistan (6.5 kg N 2 O-N ha -1 ) after application of 250 kg N ha -1 .…”

Nitrogen Management Affects Nitrous Oxide Emissions under Varying Cotton Irrigation Systems in the Desert Southwest, USA

“…The inconsistent effects of Agrotain Plus on N 2 O emissions observed here were in contrast to some results with Agrotain Plus in corn, which have shown significant mitigation of N 2 O emissions (Halvorson et al, 2014; Thapa et al, 2016). However, Watts et al (2015) also reported no effect on N 2 O emissions from DCD and NBPT addition to solid urea applied in rainfed cotton in Alabama in a 3‐yr study. The DCD in Agrotain Plus probably breaks down quickly in high temperature environments, making its use as an N 2 O emission inhibitor inconsistent (Bronson et al, 1989).…”

“…As stated above, correlations between N 2 O emission and soil water or temperature were inconsistent. Watts et al (2015) reported positive correlations between N 2 O emissions in rainfed cotton and soil temperature and soil moisture in 2 of 3 yr. The absence of N 2 O emissions in the second half of the season in FI and OSI from 2012 to 2015 was likely due to the fact that N fertilization events were finished and that large plant biomass N uptake removed most of the available soil NO 3 , and not due to a lack of soil moisture.…”

The Effects of Fertilizer Sources and Site Location on Greenhouse Gas Emissions from Creeping Bentgrass Putting Greens and Kentucky Bluegrass Roughs

“…In various agroecosystems, slow-release fertilizers have reduced N 2 O emissions compared to fastrelease fertilizers [20][21][22][23][24]. There is some evidence that coatings on URE can reduce the hydrolysis rate, which reduces gaseous losses of nitrogen [25][26][27].…”