No evidence that earthworms increase soil greenhouse gas emissions (CO2 and N2O) in the presence of plants and soil-moisture fluctuations

Author(s):  
Pierre Ganault ◽  
Johanne Nahmani ◽  
Yvan Capowiez ◽  
Isabelle Bertrand ◽  
Bruno Buatois ◽  
...  

<p>Accelerating climate change and biodiversity loss calls for agricultural practices that can sustain productivity with lower greenhouse gas emissions while maintaining biodiversity. Biodiversity-friendly agricultural practices have been shown to increase earthworm populations, but according to a recent meta-analyses, earthworms could increase soil CO<sub>2</sub> and N<sub>2</sub>O emissions by 33 and 42%, respectively. However, to date, many studies reported idiosyncratic and inconsistent effects of earthworms on greenhouse gases, indicating that the underlying mechanisms are not fully understood. Here we report the effects of earthworms (anecic, endogeic and their combination) with or without plants on CO<sub>2</sub> and N<sub>2</sub>O emissions in the presence of soil-moisture fluctuations from a mesocosms experiment. The experimental set-up was explicitly designed to account for the engineering effect of earthworms (i.e. burrowing) and investigate the consequences on soil macroporosity, soil water dynamic, and microbial activity. We found that plants reduced N<sub>2</sub>O emissions by 19.80% and that relative to the no earthworm control, the cumulative N<sub>2</sub>O emissions were 17.04, 34.59 and 44.81% lower in the anecic, both species and endogeic species, respectively. CO<sub>2</sub> emissions were not significantly affected by the plants or earthworms but depended on the interaction between earthworms and soil water content, an interaction that was also observed for the N<sub>2</sub>O emissions. Soil porosity variables measured by X-ray tomography suggest that the earthworm effects on CO<sub>2</sub> and N<sub>2</sub>O emissions were mediated by the burrowing patterns affecting the soil aeration and water status. N<sub>2</sub>O emissions decreased with the volume occupied by macropores in the deeper soil layer, whereas CO<sub>2</sub> emissions decreased with the macropore volume in the top soil layer. This study suggests that experimental setups without plants and in containers where the earthworm soil engineering effects via burrowing and casting on soil water status are minimized may be responsible, at least in part, for the reported positive earthworm effects on greenhouse gases.</p>

Problem formulation. One of the main factors affecting climate change is the greenhouse effect conditioned by adding greenhouse gases to the atmosphere, among which CO2, CH4 and N2O are the most dangerous heat-trapping gases. In addition to anthropogenic activities, the source of greenhouse gases is emissions from natural ecosystems and agroecosystems. Carbon dioxide (CO2) accounts for the largest share of greenhouse gas emissions, nitrous oxide (N2O) also has large global warming potential, being nearly 300 times higher than CO2 on a weight basis. The purpose of the study is to create the integrated model of greenhouse gas emissions from soils in the agroecosystems on the basis of studies concerning modelling carbon dioxide emissions from mineral soils, quantitatively describing nitrous oxide emissions and modelling agroecosystem productivity. Methods. Mathematical modelling of environmental processes, the synthesis of quantitative approaches to their description. Results. The results of modelling greenhouse gas emissions from soils in agro-ecosystems during 2017-2019 obtained by means of the integrated model developed showed that there is an interseasonal and interannual variability of CO2 and N2O fluxes. The higher CO2 flow rate was observed in 2017, in 2018 the lower CO2 emission intensity was discovered and in 2019 the CO2 flow rate was even lower. The emission of greenhouse gases varies depending on soil temperature, moisture and humus level of the soil. The equally low level of CO2 fluxes was observed at sufficiently low (from 1 to 6°C) soil temperatures. It was 0.072 – 0.401 g C-CO2/m2/day. The highest level of CO2 emission was observed in 2017 with a combination of high soil temperature (24-27°C) and sufficient soil moisture, and varies between 1,058 to 1,307 g С- CO2/m2/day. It was revealed that the most intense emission of N2O was observed during periods of high soil moisture when anaerobic conditions were established in the soil. The denitrification process was particularly intense in the spring of 2019, when the seasonal precipitation sum was 226 mm, and water-filled pore space (WFPS) reached more than 0.8 relative units. The average emission level of N2O was 15.592 g N-N2O/m2/day over this period, and the total N2O emission was the highest (1.134 kg of N-N2O/ha). The N2O emission intensity varied depending on the meteorological seasons. In the spring of 2017 and spring of 2018, the total N2O emission was 0.153–0.173 kg N-N2O/ha. The N2O emissions reached to 0.202-0.503 kg N-N2O/ha in the summer season and 0.192-0.660 kg N-N2O/ha in the autumn. The highest emission levels were observed in the spring seasons (2018 and 2019) and in the autumn months (2017 and 2018), an increase in soil moisture worsened soil aeration, which led to an intensive denitrification process. In total, for the three meteorological seasons the highest emission was in 2019 (1.567 kg N- N2O/ha). The emission level was lower in 2018 (1.323 kg N-N2O/ha) and even lower in 2017 (0.569 kg N-N2O/ha). Conclusions. Based on the synthesis of approaches to modelling CO2, N2O emissions and agroecosystem productivity, an integrated model of greenhouse gas emissions from soils in agro-ecosystems has been developed (plant-agrosoil-GHG-model). The interseasonal and interannual variability of CO2 and N2O fluxes and their dependence on weather conditions and humus level of the soil have been obtained.


2017 ◽  
Vol 4 (3) ◽  
pp. 62-72
Author(s):  
O. Zhukorsky ◽  
O. Nykyforuk ◽  
N. Boltyk

Aim. Proper development of animal breeding in the conditions of current global problems and the decrease of anthropogenic burden on environment due to greenhouse gas emissions, caused by animal breeding activity, require the study of interaction processes between animal breeding and external climatic conditions. Methods. The theoretical substantiation of the problem was performed based on scientifi c literature, statistical informa- tion of the UN Food and Agriculture Organization and the data of the National greenhouse gas emissions inventory in Ukraine. Theoretically possible emissions of greenhouse gases into atmosphere due to animal breeding in Ukraine and specifi c farms are calculated by the international methods using the statistical infor- mation about animal breeding in Ukraine and the economic-technological information of the activity of the investigated farms. Results. The interaction between the animal breeding production and weather-and-climate conditions of environment was analyzed. Possible vectors of activity for the industry, which promote global warming and negative processes, related to it, were determined. The main factors, affecting the formation of greenhouse gases from the activity of enterprises, aimed at animal breeding production, were characterized. Literature data, statistical data and calculations were used to analyze the role of animal breeding in the green- house gas emissions in global and national framework as well as at the level of specifi c farms with the consid- eration of individual specifi cities of these farms. Conclusions. Current global problems require clear balance between constant development of sustainable animal breeding and the decrease of the carbon footprint due to the activity of animal breeding.


Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 708
Author(s):  
Phanthasin Khanthavong ◽  
Shin Yabuta ◽  
Hidetoshi Asai ◽  
Md. Amzad Hossain ◽  
Isao Akagi ◽  
...  

Flooding and drought are major causes of reductions in crop productivity. Root distribution indicates crop adaptation to water stress. Therefore, we aimed to identify crop roots response based on root distribution under various soil conditions. The root distribution of four crops—maize, millet, sorghum, and rice—was evaluated under continuous soil waterlogging (CSW), moderate soil moisture (MSM), and gradual soil drying (GSD) conditions. Roots extended largely to the shallow soil layer in CSW and grew longer to the deeper soil layer in GSD in maize and sorghum. GSD tended to promote the root and shoot biomass across soil moisture status regardless of the crop species. The change of specific root density in rice and millet was small compared with maize and sorghum between different soil moisture statuses. Crop response in shoot and root biomass to various soil moisture status was highest in maize and lowest in rice among the tested crops as per the regression coefficient. Thus, we describe different root distributions associated with crop plasticity, which signify root spread changes, depending on soil water conditions in different crop genotypes as well as root distributions that vary depending on crop adaptation from anaerobic to aerobic conditions.


2021 ◽  
Vol 16 (3) ◽  
pp. 7-13
Author(s):  
Radik Safin ◽  
Ayrat Valiev ◽  
Valeriya Kolesar

Global climatic changes have a negative impact on the development of all sectors of the economy, including agriculture. However, the very production of agricultural products is one of the most important sources of greenhouse gases entering the atmosphere. Taking into account the need to reduce the “carbon footprint” in food production, a special place is occupied by the analysis of the volume of greenhouse gas emissions and the development of measures for their sequestration in agriculture. One of the main directions for reducing emissions and immobilizing greenhouse gases is the development of special techniques for their sequestration in the soil, including those used in agriculture. Adaptation of existing farming systems for this task will significantly reduce the “carbon footprint” from agricultural production, including animal husbandry. The development of carbon farming allows not only to reduce greenhouse gas emissions, but also to significantly increase the level of soil fertility, primarily by increasing the content of organic matter in them. As a result, it becomes possible, along with the production of crop production, to produce “carbon units” that are sold on local and international markets. The paper analyzes possible greenhouse gas emissions from agriculture and the potential for their sequestration in agricultural soils. The role of various elements of the farming system in solving the problem of reducing the “carbon footprint” is considered and ways of developing carbon farming in the Republic of Tatarstan are proposed


2020 ◽  
pp. 94-110
Author(s):  
N.V. Dvoeglazova ◽  
B.V. Chubarenko ◽  
Y.A. Kozlova

The increase in greenhouse gases in the atmosphere is influenced to a greater extent by a degree of development of industry, a growth of electrification, deforestation, and the burning of fuel for the production of heating and electricity. The contribution of emissions of each of these factors and the ratio of greenhouse gases in them should be taken into account when developing the measures to prevent climate change. According to calculations of emissions from the territory of the Kaliningrad region the burning of fuel and energy resources are supposed to be playing the main role in the greenhouse gas emission from the territory of the Kaliningrad region. In statistical reference books this activity is described as the “activities for the production and distribution of electricity, gas and water.” The usage of this fuel in the energy sector is increasing: from 1742.4 thousand tons of standard fuel in 1991 up to 2193.9 in 2016. Such little increase in total emissions is due to the general technology improvement in the country. Carbon dioxide makes up the bulk of greenhouse gas emissions from the territory of the Kaliningrad region. The percentage of the gases in the total volume is as follows: CO2 - 96.7%, CH4 - 1%, N2 O - 2.3%. Its emissions for the period from 2013 to 2016 varied from 3,757.4 in 2014 to 4,091.7 in 2015 thousand tons of standard fuel, reaching its maximum value in 2015. The estimate presented in this paper is a lower estimate, since it does not take into account emissions from industrial processes, leaks, land use, waste, etc., as well as from some categories of emission sources due to the lack of data on the use of fuel in the Kaliningrad region. Among other things, the calculations of emissions of carbon dioxide, methane and nitrous oxide from the use of fuel by vehicles in 2016, which have shown to be 1.86 times less than from burning of fossil fuels for the same year (2032.87 Gg CO2 eq. and 3914.79 Gg CO2 eq., respectively) and to account for 34.5% of the total emissions, have been made. Moreover, according to the methodology for calculating emissions the factor of carbon dioxide absorption by the region’s forests has been taken into account. The amount of carbon dioxide absorbed by forests has shown to be only 11.9% of the emissions of this gas during the combustion of boiler and furnace fuel.


2021 ◽  
pp. 1-10
Author(s):  
Eelco J. Rohling

This chapter outlines the challenge facing us. The Paris Agreement sets a target maximum of 2°C global warming and a preferred limit of 1.5°C. Yet, the subsequent combined national pledges for emission reduction suffice only for limiting warming to roughly 3°C. And because most nations are falling considerably short of meeting their pledges, even greater warming may become locked in. Something more drastic and wide-ranging is needed: a multi-pronged strategy. These different prongs to the climate-change solution are introduced in this chapter and explored one by one in the following chapters. First is rapid, massive reduction of greenhouse gas emissions. Second is implementation of ways to remove greenhouse gases from the atmosphere. Third may be increasing the reflectivity of Earth to incoming sunlight, to cool certain places down more rapidly. In addition, we need to protect ourselves from climate-change impacts that have already become inevitable.


Agronomy ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 50
Author(s):  
Ralf Liebermann ◽  
Lutz Breuer ◽  
Tobias Houska ◽  
David Kraus ◽  
Gerald Moser ◽  
...  

The rising atmospheric CO2 concentrations have effects on the worldwide ecosystems such as an increase in biomass production as well as changing soil processes and conditions. Since this affects the ecosystem’s net balance of greenhouse gas emissions, reliable projections about the CO2 impact are required. Deterministic models can capture the interrelated biological, hydrological, and biogeochemical processes under changing CO2 concentrations if long-term observations for model testing are provided. We used 13 years of data on above-ground biomass production, soil moisture, and emissions of CO2 and N2O from the Free Air Carbon dioxide Enrichment (FACE) grassland experiment in Giessen, Germany. Then, the LandscapeDNDC ecosystem model was calibrated with data measured under current CO2 concentrations and validated under elevated CO2. Depending on the hydrological conditions, different CO2 effects were observed and captured well for all ecosystem variables but N2O emissions. Confidence intervals of ensemble simulations covered up to 96% of measured biomass and CO2 emission values, while soil water content was well simulated in terms of annual cycle and location-specific CO2 effects. N2O emissions under elevated CO2 could not be reproduced, presumably due to a rarely considered mineralization process of organic nitrogen, which is not yet included in LandscapeDNDC.


2012 ◽  
Vol 63 (3) ◽  
pp. 269 ◽  
Author(s):  
J. A. Baldock ◽  
I. Wheeler ◽  
N. McKenzie ◽  
A. McBrateny

Organic carbon and nitrogen found in soils are subject to a range of biological processes capable of generating or consuming greenhouse gases (CO2, N2O and CH4). In response to the strong impact that agricultural management can have on the amount of organic carbon and nitrogen stored in soil and their rates of biological cycling, soils have the potential to reduce or enhance concentrations of greenhouse gases in the atmosphere. Concern also exists over the potential positive feedback that a changing climate may have on rates of greenhouse gas emission from soil. Climate projections for most of the agricultural regions of Australia suggest a warmer and drier future with greater extremes relative to current climate. Since emissions of greenhouse gases from soil derive from biological processes that are sensitive to soil temperature and water content, climate change may impact significantly on future emissions. In this paper, the potential effects of climate change and options for adaptation and mitigations will be considered, followed by an assessment of future research requirements. The paper concludes by suggesting that the diversity of climate, soil types, and agricultural practices in place across Australia will make it difficult to define generic scenarios for greenhouse gas emissions. Development of a robust modelling capability will be required to construct regional and national emission assessments and to define the potential outcomes of on-farm management decisions and policy decisions. This model development will require comprehensive field datasets to calibrate the models and validate model outputs. Additionally, improved spatial layers of model input variables collected on a regular basis will be required to optimise accounting at regional to national scales.


1998 ◽  
Vol 49 (1) ◽  
pp. 1 ◽  
Author(s):  
K. L. Weier

The quantities of greenhouse gases emitted into the atmosphere from sugarcane fields, and their contribution to the total emissions from Australian agriculture, have never been estimated with any degree of certainty. This review was conducted to collate the available information on greenhouse gas emissions from the Australian sugarcane crop. Estimates were made for the emissions of the 3 major greenhouse gases―carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)―from known or suspected sources. Sinks for the sequestration of the gases also have been identified. CO2 was found to be emitted during burning of the crop and from trash-blanketed and bare sugarcane fields. Total emissions from these sources in the 1994 season were estimated at 7·6 Mt CO2-C/year. However, the sugarcane crop was identified as a major sink for C, with uptake by the crop in 1994 estimated at 13· 4 Mt CO2-C/year. N2O emanating from sugarcane soils via denitrification following application of fertiliser accounted for 45-78% of total gaseous N emissions. Estimates of N2O emissions from all land under sugarcane in 1994 totalled 4·4 kt N2O-N/year from denitrification with a further 6·3 kt N2O-N emitted from areas that are still burnt. This review suggests changes in management procedures that should limit the opportunities for denitrification in the soil and thus reduce N2O emissions. Methane evolution occurs during the smouldering phase, following burning of the crop, with production estimated at 6·7 kt CH4-C/year in 1994. CH4 oxidation in soil was identified as an important process for removal of atmospheric CH4, as were trash-blanketed soils. Although these figures are our best estimate of gaseous production from sugarcane fields, there still remains a degree of uncertainty due to sampling variability and because of the extrapolation to the entire sugarcane area. However, the coupling of new laser techniques with known micrometeorological methods will allow for a more precise sampling of greenhouse gas emissions over a larger area. Estimates would thus be more representative, resulting in a greater degree of confidence being placed in them by the sugar industry.


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