N2O emissions from banana plantations in tropical China as affected by the application rates of urea and a urease/nitrification inhibitor

Abstract

In this study, we quantified N 2 O fluxes from banana plantations in China using a field experiment as well as static chamber and gas chromatography techniques. We utilized five levels of urea treatments, including CK (no urea addition); urea addition at a rate of 312 (U1), 415 (U2), 519 (U3), and 623 kg N ha −1 (U4); and a combination of urea (U3) and urease (NBPT) and nitrification (DCD) inhibitor (U3 + I) treatments. Soil temperature, moisture, and the concentrations of NH 4 + and NO 3 − have been monitored throughout the study. Compared to CK (11.8 μg m −2 h −1 and 14.2 t ha −1 , respectively), urea addition significantly increased N 2 O emission fluxes and banana yields (88.2-177 μg m −2 h −1 and 19.4-25.0 t ha −1 , respectively). The stimulation effect of urea on N 2 O emissions was significantly higher than its effect on banana yield. N 2 O emission occurred in pulses during banana cultivation due to repeated topdressing. The cumulative N 2 O emissions and N 2 O emission factor of urea applied in banana plantations were estimated to be 6.39-12.8 kg N ha −1 and 1.46-2.31 %, respectively. Notably, N 2 O emissions were significantly positively correlated with urea application rate, temperature, and NH 4 + levels, suggesting that temperature and NH 4 + availability are the most important factors controlling N 2 O emissions in tropical banana plantations. Combined NBPT and DCD treatment greatly reduced N 2 O emissions (by 65.4 %) and increased banana yields (by 4.5 %).

Responses of soil nitrous oxide production and abundances and composition of associated microbial communities to nitrogen and water amendment

“…Globally, soils a r e m a j o r s o u r c es o f N 2 O e m i s s i on s , a n d 60 % (3.5 Tg N year −1 ) of N 2 O emissions are derived from arable soils (Goldberg and Gebauer 2009;IPCC 2013). There is little doubt that increasing atmospheric concentration of N 2 O is primarily caused by the excessive use of nitrogen (N) fertilizer (Davidson 2009;Shcherbak et al 2014;Zhu et al 2015). However, N 2 O production from N fertilizer depends mainly on soil properties but also by soil moisture and the type of N fertilizer (Zhu et al 2013b;Cheng et al 2014;Wang et al 2016a;Zhang et al 2016).…”

Nitrogen Transformations Associated with N2O Emissions in Agricultural Soils

“…To reduce potentially increased ammonia volatilization after application of nitriication inhibitors, manufactures developed urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) [56,57]. Application of NBPT has been proved efective in reducing pasture soil urease activity and mitigating ammonia volatilization [58,59].…”

“…Application of NBPT has been proved efective in reducing pasture soil urease activity and mitigating ammonia volatilization [58,59]. The combination of nitriication inhibitor and NBPT could also decrease the yield-scaled N 2 O emissions relative to treatments only with fertilizer in banana plantations [56].…”

“…While it is rational to expect that grain N concentration may increase in response to soil with longer N retention time, there are studies demonstrating no such efect in grain N following DMPP application [54]. A recent study on banana plantations in tropical China reported decreased yield-scaled N 2 O emission, but banana yield showed no signiicant diference between N fertilization treatment and N with inhibitors [56]. Thereby, the eiciency of N fertilization practice with nitriication inhibitors might be crops or vegetation-type dependent, which should be considered in future applications.…”

Response of Gross Mineralization and Nitrification Rates to Banana Cultivation Sites Converted from Natural Forest in Subtropical China

“…Previous studies have found a high N retention capacity in the highly weathered soils of natural forests in subtropical or tropical regions, which exhibit high gross mineralization rates along with low gross nitrification rates [11,13]. During the conversion of forest to farmland, an input of N, preferentially provided in inorganic form, as well as frequent irrigation and tillage can greatly change the soil properties and biochemical environment (e.g., soil organic matter, water holding capacity and pH) [20][21][22][23], which may affect mineralization and nitrification rates, and N availability in soils. At the initial stage of banana cultivation via conversion from forests, tillage can increase the soil's porosity and subsequently the O 2 diffusion into the soil, which could increase microbial abundance and activity, thus accelerating the decomposition of soil organic matter [24], suggesting a possible increase in mineralization rate.…”