Interaction Between Soil and Fertiliser Nitrogen (N) Drives Plant N Uptake and Nitrous Oxide (N2O) Emissions in Tropical Sugarcane Systems

Abstract

Aims: High nitrogen (N) fertiliser inputs in intensive sugarcane systems drive productivity but also significant emissions of nitrous oxide (N2O), a potent greenhouse gas. The effects of N fertiliser inputs on native soil N availability for plant N uptake as well as N2O emissions remain unknown, hindering efficient N management. This study investigated the contribution of fertiliser and soil N and their interaction to plant N uptake and N2O emissions in two intensively managed tropical sugarcane systems with different farming practices. Methods: High temporal resolution N2O measurements were combined with 15N recoveries across four N fertiliser rates, (100, 150, 200 and 250 kg N ha-1) in soil, plant and N2O emissions. Results: Cumulative N2O emissions ranged from 0.3 to 4.1 kg N ha-1, corresponding to emission factors ranging from 0.7 to 2.4%. Native soil N accounted for > 60% of cumulative N2O emissions and total plant N uptake. Fertiliser N addition increased N2O emissions from native soil N compared to the unfertilised control. These findings highlight the interaction between fertiliser and soil N, with the latter being the dominant source for N uptake and loss. Overall fertiliser 15N loss responded exponentially to N rates with 50% of applied N fertiliser permanently lost even at the recommended N rate. Conclusions: The response of soil-derived N2O emissions to N rates largely determined the magnitude of total N2O emissions, demonstrating the importance of site and soil specific interaction between soil and fertiliser N for N2O emissions.

Denitrification Losses in Response to N Fertilizer Rates—Integrating High Temporal Resolution N2O, In Situ 15N2O and 15N2 Measurements and Fertilizer 15N Recoveries in Intensive Sugarcane Systems

“…Summary data associated with this study are available at Environmental Data Initiative via https://doi.org/10.6073/pasta/5c34f47415f55eb4e030f22c91299ad9 (Takeda et al., 2023).…”

Optimizing sowing patterns in winter wheat can reduce N2O emissions and improve grain yield and NUE by enhancing N uptake

“…N fertilization contributes to N 2 O emissions (Rahman et al, 2021). Despite a linear relationship between the cumulative N 2 O emissions and N rates (Kim et al, 2013), there is overwhelming evidence in the literature indicating that cumulative N 2 O emissions increase exponentially as the N rate increases, including evidence for grain crops around the world (Shcherbak et al, 2014), tropical sugarcane in Australia (Takeda et al, 2021), and spring wheat in New Mexico (Millar et al, 2018). Therefore, mitigation of N 2 O emissions at higher N input may be more difficult because some simple measures, such as supplementing with phosphate fertilizer (Shen and Zhu, 2022) and changing from conventional to no tillage (Campanha et al, 2019), mitigated N 2 O emissions at relatively low N input, but not at higher N rates.…”

“…N 2 O causes global warming, destroys the ozone layer, and increases ultraviolet radiation on the ground (IPCC, 2021). When seeking for the high yield or alleviating these abiotic stress in crop production, the application of N fertilizer may increase N 2 O emissions, because the soil NH 4 + and NO 3 − concentrations increase (Millar et al, 2018;Takeda et al, 2021), both of which are the substrates of nitrification and denitrification processes in soil and closely related to N 2 O emissions (Subbarao et al, 2017;Zhang et al, 2019). Therefore, increasing wheat yield while mitigating the cumulative N 2 O emissions caused by N fertilizer application is essential to ensure food security and slow global warming (Ying et al, 2019).…”