Enhanced‐efficiency nitrogen fertilizers reduce winter losses of nitrous oxide, but not of ammonia, from no‐till soil in a subtropical agroecosystem

Abstract

Nitrogen (N) gas losses can be reduced by using enhanced‐efficiency N (EEN) fertilizers such as urease inhibitors and coating technologies. In this work, we assessed the potential of EEN fertilizers to reduce winter losses of nitrous oxide (N2O‐N) and ammonia (NH3‐N) from a subtropical field experiment on a clayey Inceptisol under no‐till in Southern Brazil. The EEN sources used included urea containing N‐(n‐butyl) thiophosphoric triamide (UR+NBPT), polymer‐coated urea (P‐CU) and copper‐and‐boron‐coated urea (CuB‐CU) in addition to common urea (UR) and a control treatment without N fertilizer application. N2O‐N and NH3‐N losses were assessed by using the static chamber method and semi‐open static collectors, respectively. Both N2O‐N and NH3‐N exhibited two large peaks with an intervening period of low soil moisture and air temperature. Although the short‐term effect was limited to the first few days after application, UR + NBPT urea decreased soil N2O‐N emissions by 38% relative to UR. In contrast, urease inhibitor technology had no effect on NH3‐N volatilization. Both coating technologies (CuB‐CU and P‐CU) were ineffective in reducing N losses via N2O production or NH3 volatilization. The N2O emission factor (% N applied released as N2O) was unaffected by all N sources and amounted to only 0.48% of N applied—roughly one‐half the default factor of IPCC Tier 1 (1%). Based on our findings, using NBPT‐treated urea in the cold winter season in subtropical agroecosystems provides environmental benefits in the form of reduced soil N2O emissions; however, fertilizer coating technologies provide no agronomic (NH3) or environmental (N2O) advantages.

Duromide increase NBPT efficiency in reducing ammonia volatilization loss from urea

“…It is known that soil moisture influences the peak and duration of NH 3 -N volatilization. Ribeiro et al (2020) observed that N losses from amide fertilizers, including conventional urea and NBPT-treated urea, occurred 10 days after application and were associated with increased soil temperature and moisture.…”

“…With a delay in initial N loss, there is a greater chance for granules to be incorporated into the soil, through rainfall, for instance, reducing NH 3 -N volatilization. Dall'Orsoletta et al (2017) and Ribeiro et al (2020) observed that NBPT was effective in reducing soil NH 4 + levels in the first days after application compared with conventional urea. In the current study, we found that at 45 kg ha -1 of N, Ur-NBPT delayed the volatilization peak by one day compared with Ur.…”

“…However, the benefits of NBPT-treated urea do not always translate into yield gains in crop production (Dillon et al, 2012;Prando et al, 2013;Cancellier et al, 2016;Guardia et al, 2017;Yang et al, 2020). Moreover, NBPT does not seem efficient in reducing NH 3 -N losses under certain conditions (Ribeiro et al, 2020). There are uncertainties about the efficiency of NBPT, because higher temperatures, higher humidity, and the presence of straw in the soil can accelerate the degradation of this molecule, decreasing its efficiency in reducing losses due to NH 3 -N volatilization (Suter et al, 2011;Engel et al, 2013;Mira et al, 2017).…”

Sustainable soil management and climate change mitigation

“…From a climate mitigation perspective, it is imperative to reduce N 2 O emissions by lowering N input to soil, or fine tuning the N cycling process to completely oxidize ammonia to nitrate without producing N 2 O as a by‐product (Jansson & Hofmockel, 2020). Researchers are developing a variety of strategies, for example urease inhibiting and coating technologies have been tried to reduce soil N 2 O emission, with varying levels of success (Ribeiro et al., 2020).…”

Productivity and profitability of maize as affected by nitrogen sources and rates

“…Conventional urea is the most common N source used by maize farmers worldwide (Heffer & Prud'homme, 2016). The popularity of conventional urea can be explained by its high N content (44-46%), low cost, and ease of application (Ribeiro et al, 2020). On the other hand, its greatest disadvantage is the high susceptibility to ammonia (NH 3 ) volatilization.…”