N2O emission increases with mulch mass in a fertilized sugarcane cropping system

Abstract

The nitrous oxide (N 2 O) emitted from soil was monitored to investigate the effect of sugarcane straw removal on the mechanisms that make mulch a Bhot spot^of N 2 O emissions under subtropical conditions. We conducted a field experiment with the firstratoon sugarcane with four amounts of straw (0, 4, 8, and 12 Mg ha −1) at the soil surface combined with 0 or 100 kg urea-N ha −1. The urea-N was applied 52 days after straw application. Over the course of 1 year, we measured the N 2 O and carbon dioxide (CO 2) emissions, mineral nitrogen (N), soil moisture and temperature, and remaining straw carbon (C) and N in the mulch. We observed two Bhot moments^for N 2 O emissions: the first one immediately after sugarcane straw application to soil and the second one after fertilizer-N application. High amounts of straw left on the soil led to an increase in the water-filled pore space (WFPS), and both WFPS and straw-C were strongly correlated with N 2 Ofluxes.CumulativeN 2 O increased from 510 (0 Mg + N) to 1055 (12 Mg + N) g N 2 ON ha −1 for the fertilized straw treatments. The N 2 O emission factors (EFs) of the sugarcane straw N and the fertilizer-N increased linearly with straw quantity, i.e., were not constant but were lower than the IPCC default values. Over 70% of the cumulative N 2 O emissions measured in straw + fertilizer-N treatments for 1 year were attributed to the presence of straw mulch, which emphasized the importance of the straw layer at the soil surface as a hot spot for N 2 O emissions.

Greenhouse gas emissions from tropical coastal wetlands and their alternative agricultural lands: Where significant mitigation gains lie

“…Thus, improved management of fertiliser applications could result in GHG emission mitigation through reduced N2O emissions. Some activities include split application of nitrogen fertiliser in combination with low irrigation, reduction in fertiliser application rates, substitution of nitrate-based fertiliser for urea (Rashti et al, 2015), removing mulch layer before fertiliser application (Pinheiro et al, 2019;Xu et al, 2019) or conversion of sugarcane to wetlands.…”

Regulation of the product stoichiometry of denitrification in intensively managed soils

“…Thus, we concluded that organic matter amendment can mitigate N 2 O emissions in soils with low NO 3 − content (due to higher N 2 O reduction), or trigger N 2 O fluxes when coupled with high soil NO 3 − content under the moist situation. Earlier studies reported that straw amendment has the potential to mitigate N 2 O emissions (Yao et al., 2017; Zou et al., 2005), while others showed that straw returning can increase N 2 O losses (Pinheiro et al., 2019; Wu et al., 2018). In this context, we believe that our study contributes to the understanding of why contradictory observations on the impact of straw addition on N 2 O fluxes have been reported.…”

Biochar Is Comparable to Dicyandiamide in the Mitigation of Nitrous Oxide Emissions from Camellia oleifera Abel. Fields

“…A previous study demonstrated that soil temperature and moisture can explain up to 86% variations of N 2 O emissions [39]. Soil N 2 O emissions varied with soil temperature in specific ranges [28,40], which may relate to different optimum temperatures of N-transforming microorganisms with or without N fertilization and different soil types [37,41]. Compared with soil temperature, soil moisture is the main factor impacting soil N 2 O emissions.…”