Contrasting effects of straw and biochar on microscale heterogeneity of soil O2 and pH: Implication for N2O emissions

Zhu, Kun; Ye, Xin; Ran, Hongyu; Zhang, Peixuan; Wang, Gang

doi:10.1016/j.soilbio.2022.108564

Cited by 40 publications

(20 citation statements)

References 14 publications

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“…Oxygen optodes in non-waterlogged soils. In-situ measurements of soil O2 contents with optical sensors have been investigated in a number of studies, especially in combination with amendments of organic fertilizers 19,23,24 . That is because the availability and spatial distribution of O2 have immense impacts on C and N cycling as well as greenhouse gas emissions.…”

Section: Resultsmentioning

confidence: 99%

“…Some optodes, such as for pH and O2, are well-established tools to study complex environments, in particular sediments and waterlogged soils 17,18 . However, only a few studies applied optodes within non-waterlogged soils 19,[20][21][22][23][24][25][26] . Most relevant soil processes, from an agricultural perspective, should be studied at lower water contents relevant for plant growth (40-90 % of the water holding capacity (WHC)).…”

Section: Introductionmentioning

confidence: 99%

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Optical Chemical Sensors for Soil Analysis: Possibilities and Challenges of Visualizing NH3 Concentrations as well as pH and O2 Microscale Heterogeneity

Merl

Pedersen

et al. 2022

Preprint

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Agricultural nitrogen (N) application to soils is the main source of atmospheric ammonia (NH3) emissions. Ammonia negatively impacts the environment on a large scale. These emissions are affected by spatiotemporal heterogeneities of parameters within the soil on a microscale. Some key parameters controlling processes of the N cycle are soil oxygen (O2) and pH. To better understand biogeochemical soil processes and NH3 emissions we propose the application of optical chemical sensors (optodes) in soils. The use of optodes in soil science is in its infancy. In this study, we investigated the possibilities and challenges of using optodes in non-waterlogged soils with the extended application of a recently developed NH3 optode in combination with pH and O2 optodes in two different soils and with different fertilizers. Our results demonstrated the possibility to visualize reductions of NH3 concentrations by 76 % and 87 % from the incorporation of sludge compared to the surface application of sludge. We showed in 2D how soil pH and fertilizer composition correlate with NH3 volatilization. Our measurements revealed that pH optodes show certain advantages over conventional methods when measuring pH in soils in-situ. Lastly, we investigated spatiotemporal dynamics of O2 at different soil water contents and discussed potential challenges, which can lead to measuring artifacts.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optical Chemical Sensors for Soil Analysis: Possibilities and Challenges of Visualizing NH3 Concentrations as well as pH and O2 Microscale Heterogeneity

Merl

Pedersen

et al. 2022

Preprint

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“…On the other hand, the degradation of straw and nitrification of ammonium from N fertilizer could both enhance the soil O 2 consumption rate (Figure 8), resulting in fast development of anoxic conditions, consequently slow down C mineralization of added straw in the later stage (Figure 1). In the treatment with co‐addition of charred straw and straw, the porous structure of the charred straw could improve soil aeration and slow down the anoxia development (Zhu et al, 2022), caused by straw and N fertilizer (Figure 8), thereby stimulating the production and emission of soil CO 2 . Furthermore, the fast consumption of DOC and the relatively high contents of microbial biomass in the initial incubation (Figures 5 and S1) revealed the significant interactions of straw and charred straw on C mineralization.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, numerous studies have indicated that the application of biochar into soils can markedly reduce N 2 O emissions (Cayuela et al, 2014; Wang et al, 2018), possibly due to the improved soil aeration, sorption of mineral N on the surface of biochar (Fidel et al, 2018), and the elevated pH (Kammann et al, 2017). Furthermore, lots of studies revealed that the straw and straw derived biochar had contrasting effects on soil properties and relevant gas emissions (Zhang et al, 2017; Zhu et al, 2022), while the straw and straw derived biochar could be applied together in the field experiment (Sun et al, 2020). However, there is limited information on the influences of co‐applying straw and straw derived biochar on soil N 2 O emissions.…”

Section: Introductionmentioning

confidence: 99%

Delayed nitrogen application after straw and charred straw addition altered the hot moment of soil N₂O emissions

Ran

Wang

et al. 2023

European J Soil Science

Self Cite

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The combination of nitrogen (N) fertilization and straw incorporation has complex influences on soil N transformations and derived nitrous oxide (N2O) emissions. This study aimed to reveal the coupled effects of straw returning forms and N fertilizer management on soil N2O emissions. Here, carbon (C) sources with varied availabilities were supplied by different straw returning forms, including straw, charred straw, and combined application of straw and charred straw. The time gaps between additions of exogenous N and C sources were carried out by managing the timing of N fertilization, including N application simultaneous with or delayed after straw return. Soil N2O emissions under different straw returning forms and their response relationships to soil C, N, microbial biomass, as well as soil pH and oxygen (O2) were explored. Co‐application of straw and N fertilizer provided sufficient C and N sources, enhanced the microbial biomass, and consequently increased N2O emissions. Delayed N fertilization could decouple the response of N2O emissions to straw addition, because of constrained N availability and limited pH decline, which decreased the cumulative N2O emissions significantly. Possibly due to straw induced N immobilization coupled with charred straw induced pH elevation, the combined application of straw and charred straw constrained soil N2O emissions compared with straw only application, regardless of N fertilizer management. By shaping the microbial biomass and soil C, N, and O2 dynamics, delayed application of N fertilizer could further enhance the inhibition effect of the charred straw and straw combination on soil N2O emissions. Therefore, the varied straw returning forms and the timing of N fertilization could affect the supply of available C and N, influencing the hot moments of N2O emissions, and the joint addition of straw and charred straw with a few weeks delayed N application could possibly reduce the risk of soil N2O emissions from straw return systems. Such mitigation potential should be evaluated further under field conditions. Highlights Delayed N fertilization attenuated the magnitude of N2O emissions after straw additions. Combination of charred straw with straw mitigated N2O emissions, further enhanced by delayed N fertilization. Soil pH was the chief regulator for N2O emissions under different straw returning forms and N application.

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“…This could also be evidenced by the significant increase in the EOC content in the 0.1%ST treatment relative to the 0.1%BC treatment, albeit no significant change in the SOC/NO 3 − ratio was observed (Table 1). On the other hand, straw amendment would create a more anaerobic environment favoring the nitrate reduction processes because its decomposition can lower the oxygen level at microsites and provide labile C for soil microorganisms (Chèneby et al 2010;Zhu et al 2022).…”

Section: Mechanisms Of Biochar Amendment Effectsmentioning

confidence: 99%

Biochar amendment alters the partitioning of nitrate reduction by significantly enhancing DNRA in a paddy field

Wei

Şenbayram

Zhao

et al. 2022

Biochar

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Using 15N tracer technique, we investigated the potential rates of denitrification, anaerobic ammonium oxidation, dissimilatory nitrate reduction to ammonium (DNRA), and their partitioning among nitrate reduction, as well as the N2O emission rates in a paddy soil receiving various biochar (0%, 0.03%, 0.1%, 0.5%, and 1.0%; w/w) and straw (0.1%) over six consecutive years. Results showed that except for the 1.0% amendment treatment, biochar significantly (P < 0.05) increased denitrification rates by 10.19‒75.96% compared with non-biochar amended treatment, and that biochar significantly (P < 0.05) increased DNRA rates by 1.63‒6.84 folds relative to non-biochar amended treatment. Consequently, biochar shifted more NO3– partitioning toward DNRA process, as suggested by the increased DNRA/(denitrification + DNRA) ratios from 1.60 to 13.18%. On the other hand, biochar significantly (P < 0.05) reduced N2O emission rates by 61.86–97.65% accompanied by a significant decrease in N2O/(N2O + N2) ratios (65.29–98.39%), indicating biochar amendment facilitated the reduction of N2O to N2. The promoting effects of biochar on DNRA rates and DNRA/(denitrification + DNRA) ratios were attributed to the increased carbon availability and the altered nitrate reducer communities. Collectively, our study suggests that biochar amendment in the paddy soil is helpful for N conservation by favoring nitrate partitioning toward DNRA process, which deepens our understanding of how biochar mediates N cycling in the paddy field. Graphical Abstract

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Contrasting effects of straw and biochar on microscale heterogeneity of soil O2 and pH: Implication for N2O emissions

Cited by 40 publications

References 14 publications

Optical Chemical Sensors for Soil Analysis: Possibilities and Challenges of Visualizing NH3 Concentrations as well as pH and O2 Microscale Heterogeneity

Optical Chemical Sensors for Soil Analysis: Possibilities and Challenges of Visualizing NH3 Concentrations as well as pH and O2 Microscale Heterogeneity

Delayed nitrogen application after straw and charred straw addition altered the hot moment of soil N₂O emissions

Biochar amendment alters the partitioning of nitrate reduction by significantly enhancing DNRA in a paddy field

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Contrasting effects of straw and biochar on microscale heterogeneity of soil O2 and pH: Implication for N2O emissions

Cited by 40 publications

References 14 publications

Optical Chemical Sensors for Soil Analysis: Possibilities and Challenges of Visualizing NH3 Concentrations as well as pH and O2 Microscale Heterogeneity

Optical Chemical Sensors for Soil Analysis: Possibilities and Challenges of Visualizing NH3 Concentrations as well as pH and O2 Microscale Heterogeneity

Delayed nitrogen application after straw and charred straw addition altered the hot moment of soil N2O emissions

Biochar amendment alters the partitioning of nitrate reduction by significantly enhancing DNRA in a paddy field

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Delayed nitrogen application after straw and charred straw addition altered the hot moment of soil N₂O emissions