Interaction between soil and fertiliser nitrogen drives plant nitrogen 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. Fertiliser and soil N availability for both plant N uptake and N2O emissions across different N rates 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. 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, highlighting the interaction between fertiliser and soil N, which determined the overall magnitude but also the response of total N2O emissions to N rates dependent on the site conditions. 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 interaction between fertiliser and soil N and its contribution to N uptake and N2O emissions demonstrate the importance of integrating soil fertility management with N fertiliser rate recommendations for sugarcane systems to maintain crop productivity and reduce environmental impacts.

Denitrification losses in response to N fertiliser rates - a synthesis of high temporal resolution N2O, in-situ 15N2O and 15N2 measurements and fertiliser 15N recoveries in intensive sugarcane systems

“…In this study, in-situ measurements of N 2 O and N 2 emissions from two sugarcane systems were combined with previously reported high temporal resolution measurements of N 2 O (Takeda et al, 2022;Takeda et al, 2021a) and recovery of 15 N-labelled fertiliser in the plant, soil and N 2 O (Takeda et al, 2022;Takeda et al, 2021b) presented in the previous studies to quantify seasonal N 2 O and N 2 losses.…”

“…The field experiments were conducted on commercial sugarcane farms in Burdekin,QLD (19° 37' 4'' S,147° 20' 4'' E) from October 2018 to August 2019 and in Mackay, QLD (21° 14' 4'' S, 149° 04' 6'' E) from October 2019 to August 2020, described in details in Takeda et al (2022). The climate is tropical in both Burdekin and Mackay.…”

“…A steel base (0.22 m × 0.22 m at the Burdekin site and 0.2 m × 0.4 m at the Mackay site) was installed in each micro plot and 15 N enriched urea fertiliser (70 atom%) was applied inside the base at the corresponding rates. Gas sampling was conducted with static closed chambers at the Burdekin site from November 2018 to February 2019 and with semi-automated chambers at the Mackay site from October 2019 to January 2020 (Takeda et al (2022), Supporting Information S1.3). The gas samples were analysed for the concentration of N 2 O and CO 2 using a Shimadzu GC-2014 Gas Chromatograph (Shimadzu, Kyoto, Japan) and for different isotopologues of N 2 and N 2 O using an Isotope Ratio Mass Spectrometer (IRMS) (20-22 Sercon Limited, UK).…”

“…Plant and soil samples were taken from each of the 2.0 m sections prior to harvest (on 27-28 August 2019 at the Burdekin site and 25-26 August 2020 at the Mackay site). The procedure of plant and soil sampling and analyses are detailed in Takeda et al (2021b) and Takeda et al (2022) as well as Supporting Information S1.5. Briefly, aboveground sugarcane biomass, trash on the ground, two green leaves at the 3 rd node from the section and the adjacent row and remaining stools and major roots of sugarcane were harvested.…”

Nitric oxide: A core signaling molecule under elevated GHGs (CO2, CH4, N2O, O3)-mediated abiotic stress in plants

“…To compensate the gap created due to nutrient deficiency, mineral fertilizers are applied ( Wong, 1979 ; Tissue et al., 1997 ; Stitt and Krapp, 1999 ). However, excessive N-rich fertilizer applications cause an increase in CH 4 and N 2 O production ( Takeda et al., 2022 ; Timilsina et al., 2020a ; Xu et al., 2016 ). Nitrogen is the most abundantly used essential macronutrient in agriculture.…”