Effect of biochar on soil CO2 production

Received: 2016-06-13 | Accepted: 2016-12-13 | Available online: 2017-12-31http://dx.doi.org/10.15414/afz.2017.20.04.72-77The study focuses on looking for answers to the following questions: 1. Is biochar application a suitable solution for reducing CO2 emissions? 2. What application rate significantly reduces CO2 production to the atmosphere? 3. Does have the application of enriched biochar a justification in relation to reducing CO2 production? The experiment was established on Haplic Luvisol at the experimental site of SUA in Nitra (Dolná Malanta), where we measured CO2 emissions from the soil to the atmosphere under the following treatments: different rates (0, 10, 20 t ha-1) of pure biochar (B0, B10 a B20) and enriched biochar (EB10, EB20) combined with different levels of mineral nitrogen at doses of 0, 40 and 80 kg ha-1 (N0, N40, N80). Overall, the average values of CO2 emissions were lower by 19.8 %, 13.3 %, 12.9 %, 9.4 % and 8.7 % in B10N0, B20N40, B20N0, B20N80 and B10N40 treatments as compared to B0N0 (control) during the studied period. On the other hand, the average values of CO2 were higher by 20% in B10N80 treatments as compared to control (B0N0). Application of enriched biochar whether individually (EB10N0, EB20N0) or with additional N (EB10N40, EB20N40, EB10N80, EB20N80) increased average CO2 by 29.7 %, 34.6 %, 36.0 %, 44.9 %, 45.8 % and 53.6 % as compared to control (B0N0). The cumulative CO2 emissions for the whole studied period (2014) were in the following order from the lowest one B10N0 < B20N0 < B20N40 < B20N80 < B10N40 < B0N0 (control) < B10N80 < EB20N40 < EB20N80 < EB10N80 < EB20N0 < EB10N0 < EB10N40.Keywords: biochar, enriched biochar, N-fertilization, CO2 emissionReferences ALVAREZ, R. et al. (1995) Soil respiration and carbon inputs from crops in a wheat-soybean rotation under different tillage systems. In Soil Use Mamagment, Vol. 11,  pp. 45–50 doi: http://dx.doi.org/10.1111/j.1475-2743.1995.tb00495.xBIELEK, P. 2001. Carbon sequestration by soil effets. In Humic substances in ecosystems 4. Bratislava : VÚPOP, 2001, pp. 11–14.Duiker, S.W. and Lal, R. (1999) Crop residue and tillage effects on carbon sequestration in a Luvisol in central Ohio. In Soil Tillage Res., vol. 52, pp. 73–81. doi: http://dx.doi.org/10.1016/S0167-1987(99)00059-8Dukes, J.S. and Hungate, B.A. (2002) Elevated carbon dioxide and litter decomposition in California annual grasslands: which mechanisms matter? In Ecosystems, vol. 5, pp. 171–183. doi: http://dx.doi.org/10.1007/s10021-001-0063-7Fischer, D. and Glaser, B. (2012) Synergisms between Compost and Biochar for Sustainable Soil Amelioration. In Kumar, S. (ed.) Management of Organic Waste. Earthscan, Rijeka, pp. 167–198.GREGORICH, E.G. et al. (1998) Carbon distribution and losses: erosion and deposition effects. In Soil and Tillage Research, vol. 47, pp. 291–302. doi: http://dx.doi.org/10.1016/S0167-1987(98)00117-2HAN, F. et al. (2016) Effect of biochar on the soil nutrients about different grasslands in the Loess Plateau. In Catena, vol. 137, pp. 554–562. doi: http://dx.doi.org/10.1016/j.catena.2015.11.002Heitkötter, J. and Marschner, B. (2015) Interactive effects of biochar ageing in soils related to feedstock, pyrolysis temperature, and historic charcoal production. In Geoderma, vol. 245–246, pp. 56–64. doi: http://dx.doi.org/10.1016/j.geoderma.2015.01.012IPCC, (2014): Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.Jacinthe, P.A. et al. (2002) Carbon budget and seasonal carbon dioxide emission from a central Ohio Luvisol as influenced by wheat residue amendment. In Soil Tillage Res., vol. 67, pp. 147–157. doi: http://dx.doi.org/10.1016/S0167-1987(02)00058-2Jeffery, S. et al. (2011) A quantitative review of the effects of biochar application to soils on crop productivity using meta-analysis. In Agric. Ecosyst. Environ., vol. 144, pp. 175–187. doi: http://dx.doi.org/10.1016/j.agee.2011.08.015Jien, S.H. and Wang, Ch.S. (2013) Effects of biochar on soil properties and erosion potential in a highly weathered soil. In Catena, vol. 110, pp. 225–233. doi: http://dx.doi.org/10.1016/j.catena.2013.06.021JUMA, N.G. (1994) A conceptual framework to link carbon and nitrogen cycling to soil structure formation. In Agric. Ecosyst. Environ., vol 51, pp. 257–267.JUMA, N.G. (1999) Pedosphere and its dynamics. 1 vyd. Edmonton (Canada) : Salman Productions Ins., 1999. 335 s. ISBN 1-896263-10-0.Kammann, C. et al. (2011) Influence of biochar on drought tolerance of Chenopodium quinoa: Willd and on soil–plant relations. In Plant Soil, vol. 345, pp. 195–210. doi: http://dx.doi.org/10.1016/j.catena.2013.06.021Lal, R. (2008) Carbon sequestration. In Philos. Trans. R. Soc., vol. 363, pp. 815–830. doi:http://dx.doi.org/10.1098/rstb.2007.2185Laird, D.A. et al. (2010) Impact of biochar amendments on the quality of a typical Midwestern agricultural soil. In Geoderma, vol. 158, pp.  443–449. doi:http://dx.doi.org/10.1016/j.geoderma.2010.05.012Lopez-Capel, E. et al. (2016) Biochar properties, In: Shackley, S. et al. (eds.): Biochar in European soils and agriculture, Routledge, London, New Your, pp. 41–72.MONREAL, C.M. et al.  (1995) Soil organic structures in macro and microaggregates of a cultivated brown chernozem. In Soil Biol. Biochem., vol. 27, pp. 845–853. doi: http://dx.doi.org/10.1016/0038-0717(94)00220-UPASCUAL, J.A. et al. (1998) Carbon Mineralization in an Arid Soil Amended with Organic Wastes of Varying Degerees of Stability. In Commun. Soil. Sci. Plant Anal., vol. 29, pp. 835–846. doi: http://dx.doi.org/10.1080/00103629809369989POPELÁROVÁ, E. et al. (2002) Mineralization activity in soils for the development of the precision farming system. In Arch. Acker Pfl. Boden, vol. 48, pp. 147–153.REICOSKY, D.C. and LINDSTROM, M.J. (1995) Impact of fall tillage on short-term carbon dioxide flux. In Soil and global change, pp. 177–187.ŠIMANSKÝ, V. (2016) Effects of biochar and biochar with nitrogen on soil organic matter and soil structure in Haplic Luvisol. In Acta fytotechnica et zootechnica, vol. 19, pp. 129–138. doi: http://dx.doi.org/10.15414/afz.2016.19.04.129-138ŠIMANSKÝ, V. et al. (2017) Carbon sequestration in water-stable aggregates under biochar and biochar with nitrogen fertilization. In Bulgrian Journal of Agricultural Research, vol. 23 (2) – in printSINGH, B.P. and COWIE, A.L. (2014) Long-term influence of biochar on native organic carbon mineralisation in a low-carbon clayey soil. In Sci. Report., vol. 4, pp. 1–9. doi: http://dx.doi.org/10.1038/srep03687YUAN, J.H. and XU, R.K. (2012) Effects of biochars generated from crop residues on chemical properties of acid soils from tropical and subtropical China. In Soil Res., vol. 50, pp. 570–578. doi: http://dx.doi.org/10.1071/SR12118

Evaluation of N2O emissions by DNDC model for sandy loam soils of danubian lowland

Except for food production the sector of agriculture contribute significantly to emissions of some Greenhouse gases (GHGs), especially N2O. Agricultural practices (especially increase of N consumption in the sector) are now recognized as a major factor influencing increase of N2O emissions into the atmosphere. Estimates of greenhouse gas emissions from the agricultural sector both at a local and regional level are necessary to create possible mitigation strategies with respect to environmental efficiency and economic possibility. We used the DNDC (DeNitrification and DeComposition) model that simulates a full carbon (C) and nitrogen (N) balance, including different C and N pools, and the emissions of all relevant trace gases from soils as NH3, N2O, NO, NO2 and N2. However, for this study only N2O was considered. Intergovernmental Panel on Climate Change (IPCC, 1997) includes methodologies for calculating both direct and indirect emissions of N2O related to agricultural production. Finally, the modeled emissions by DNDC were compared with those estimated according to IPCC methodology at a regional level. The rules of a good practice in GHGs inventory in agriculture were taken into account. The N2O emissions estimated by DNDC model ranged 0,09–0,68 kg N2O‐N/ha yr with an average value of 0,28 kg N2O‐N/ha yr. The N2O emissions estimated according to IPCC methodology ranged 0,46–2,86 kg N2O‐N/ha yr with an average value of 1,66 kg N2O‐N/ha yr. Simulated N2O emissions were lower than the N2O emissions estimated by IPCC methodology (1997). The simulated N2O emissions ranged 0,04–0,51 % of the total N applied to a field as a mineral N‐fertilizer. If DNDC and IPCC emissions are compared in this study, it can be concluded that simulated (DNDC) emissions are in the range of default emission factors (1,25 ±1 %) defined by IPCC methodology (1997), except for 2002. N2O emisijų iš priesmėlio dirvožemių Dunojaus žemumoje įvertinimas, taikant DNDC modelį Santrauka Dėl žemės ūkio sektoriaus, išskyrus maisto gamybą, kai kurių šiltnamio efektą sukeliančių dujų (ŠED), ypač N2O, emisijos labai padidėja. Žemės ūkis (ypač sektoriuje didinant naudojamo N kiekius) dabar laikomas pagrindiniu veiksniu, turinčiu įtakos didėjančiai N2O emisijai atmosferoje. Atsižvelgiant į ekonomines galimybes ir aplinkos apsaugos efektyvumą vietiniu ir regioniniu lygiais būtina sukurti ŠED mažinimo strategiją. Taikytas DNDS (denitrifikacijos ir destruktūrizaci jos) modelis, imituojantis anglies (C) ir azoto (N) balansą, įskaitant skirtingas C ir N sankaupas, ir visų tiesiogiai susijusių dujų, tokių, kaip: NH3, N2O, NO, NO2 ir N2 pėdsakų iš grunto emisijas. Tačiau šiame tyrime buvo atsižvelgta tik į N2O. Tarpvyriausybinė klimato kaitos tyrimų specialistų grupė (IPCC, 1997) parengė tiesioginės ir netiesioginės N2O emisijos, susijusios su žemės ūkio gamyba, apskaičiavimo metodikas. Galiausiai pagal DNDS modeliuotos emisijos buvo palygintos su įvertintomis pagal IPCC metodiką regioniniu lygiu. N2O emisija, nustatyta pagal DNDS modelį, kito nuo 0,09 iki 0,68 kg N2O–N/ha m, vidutinė vertė – 0,28 kg N2O–N/ha m. N2O emisija, nustatyta pagal IPCC metodiką, kito nuo 0,46 iki 2,86 kg N2O–N/ha m, vidutinė vertė – 1,66 kg N2O–N/ha m. Sumodeliuotoji N2O emisija buvo mažesnė nei N2O emisija, įvertinta pagal IPCC metodiką (1997), ir kito 0,04–0,51 % nuo bendrojo N, naudoto lauke kaip mineralinė N trąša. DNDS ir IPCC emisijų palyginimas leidžia teigti, kad sumodeliuotųjų (DNDS) emisijų kitimas atitinka pagal IPCC metodiką (1997) nustatytųjų emisijų ribas (1,25 ± 1 %), išskyrus 2002 metus. Reikšminiai žodžiai: N2O emisija, DNDS modelis, klimato kaita, šiltnamio efektą sukeliančios dujos (ŠED), IPCC metodika, emisijos veiksniai. Оценка с использованием модели ДНДС эмиссий N2O из почвы в низменности Дуная Резюме Сектор сельского хозяйства в значительной мере способствует эмиссии газа, в особенности N2O, вызывающего парниковый эффект. Для оценки эмиссии этого газа из сектора сельского хозяйства на местном и региональном уровнях необходимо создать возможную стратегию уменьшения эмиссий, обращая внимание на эффективность охраны окружающей среды и экономические возможности. Нами использована модель ДНДС (денитрификации и деструктуризации), которая имитирует полный баланс углерода (C) и азота (N), включая различные скопления C и N и других газов, таких как NH3, N2O, NO, NO2 и N2, а также следы эмиссий из грунта. В этом исследовании внимание уделялось лишь N2O. Межправительственная группа по изменению климата (IPCC, 1997) подготовила методики для расчета прямой и косвенной эмиссии N2O, связанной с сельскохозяйственным производством. Эмиссии, смоделированные с использованием ДНДС, были сравнены с эмиссиями, оцененными по методике IPCC, на региональном уровне. При этом основывались на правилах удачной практики, применявшейся во время инвентаризации газа парникового эффекта в сельском хозяйстве. Эмиссия N2O, установленная с использованием модели ДНДС, изменялась в пределах от 0,09 до 0,68 кг N2O-N/гa м, ее среднее значение было 0,28 кг N2O-N/гa м. Эмиссия N2O, установленная по методике IPCC, изменялась в пределах от 0,46 до 2,86 кг N2O-N/гa м, среднее значение было 1,66 кг N2O-N/гa м. Смоделированная эмиссия N2O была меньше, чем эмиссия N2O, рассчитанная по методике IPCC. Смоделированная эмиссия N2O менялась в пределах от 0,04 до 0,51 % от общего N, который использовался как минеральное удобрение. Сравнение эмиссий, полученных по методикам ДНДС и IPCC, позволяет утверждать, что смоделированные эмиссии (ДНДС) изменяются в пределах факторов эмиссии, указанных по методике (1,25 ± 1 %) IPCC (1997), за исключением 2002 года. Ключевые слова: эмиссия N2O, модель ДНДС, потепление климата, газ, способствующий парниковому эффекту, методика IPCC, факторы эмиссии. Firstd Published Online: 14 Oct 201

Mitigation of greenhouse gas emissions with Biochar application in compacted and uncompacted soil

Biochar may offer a substantial potential as a climate change mitigation and soil improvement agent, however little is known about its effects in fertile soils subjected to standard agricultural practices. The aim of this short–term (60 days) lab experiment, under controlled temperature and soil moisture regimes, was to investigate the interaction between soil compaction and fertiliser and biochar addition in relatively fertile Luvisol. Three different biochar types and two soil compaction levels were investigated to describe their interactive effect on soil greenhouse gas emission (GHG). A very strong effect of soil compaction on N2O emission (+280%) and an inter-action with biochar were found. The cumulative N2O emissions from the compacted soil were higher (+70–371%, depending on the biochar type) than the uncompacted soil. Soil compaction resulted in a faster onset and a faster decrease of N2O production. Biochar did not affect the temporal dynamics of N2O evolution from either soil. The addition of digestate/crop biomass biochar has resulted in a significant increase in CO2 evolution both in compacted and uncompacted soils, compared to hardwood and wood pallet biochar. In the compacted soil, NH4+ availability was positively related to N2O efflux, and CO2 emission was positively correlated to both NH4+ and SOC content. An increase in GHGs as a result of an increase in NH4+ availability was seen both in compacted and uncompacted soils, while the rates of N2O emission were modified by biochar type. Our results show a strong interaction between biochar and soil conditions and a strong effect of biochar type on GHG emissions from agricultural soils

Biochar and biochar with N-fertilizer affect soil N2O emission in Haplic Luvisol

The benefits of biochar application are well described in tropical soils, however there is a dearth of information on its effects in agricultural temperate soils. An interesting and little explored interaction may occur in an intensive agriculture setting; biochar addition may modify the effect of commonplace N-fertilization.We conducted a field experiment to study the effects of biochar application at the rate of 0, 10 and 20 t ha−1 (B0, B10 and B20) in combination with 0, 40 and 80 kg N ha−1 of N-fertilizer (N0, N40, N80).We followed nitrous oxide (N2O) emissions, analysed a series of soil physicochemical properties and measured barley yield in a Haplic Luvisol in Central Europe. Seasonal cumulative N2O emissions from B10N0 and B20N0 treatments decreased by 27 and 25% respectively, when compared to B0N0. Cumulative N2O emissions from N40 and N80 combined with B10 and B20 were also lower by 21, 19 and 25, 32%, respectively compared to controls B0N40 and B0N80. Average pH was significantly increased by biochar addition. Increased soil pH and reduces NO−3 content seen in biochar treatments could be the two possible mechanisms responsible for reduced N2O emissions. There was a statistically significant increase of soil water content in B20N0 treatment compared to B0N0 control, possibly as a result of larger surface area and the presence of microspores having altered pore size distribution and water-holding capacity of the soil. Application of biochar at the rate of 10 t ha−1 had a positive effect on spring barley grain yield

Biochars in soils : towards the required level of scientific understanding

Key priorities in biochar research for future guidance of sustainable policy development have been identified by expert assessment within the COST Action TD1107. The current level of scientific understanding (LOSU) regarding the consequences of biochar application to soil were explored. Five broad thematic areas of biochar research were addressed: soil biodiversity and ecotoxicology, soil organic matter and greenhouse gas (GHG) emissions, soil physical properties, nutrient cycles and crop production, and soil remediation. The highest future research priorities regarding biochar's effects in soils were: functional redundancy within soil microbial communities, bioavailability of biochar's contaminants to soil biota, soil organic matter stability, GHG emissions, soil formation, soil hydrology, nutrient cycling due to microbial priming as well as altered rhizosphere ecology, and soil pH buffering capacity. Methodological and other constraints to achieve the required LOSU are discussed and options for efficient progress of biochar research and sustainable application to soil are presented.Peer reviewe

Effect of Biochar and Biochar Combined with N-Fertiliser on Soil Organic Carbon Content

An experiment of different application rates of biochar and biochar combined with nitrogen fertiliser was conducted at experimental field on a Haplic Luvisol located in Nitra region of Slovakia during the growing season of spring barley (2014). The aim of this study was to evaluate the effects of biochar and biochar combined with nitrogen fertilisation on the soil organic carbon (SOC). The treatments consisted of 0, 10 and 20 t/ha of biochar application (B0, B10 and B20) combined with 0, 40 and 80 kg/ha N of nitrogen fertiliser applied (N0, N40 and N80). The results showed that SOC content at the beginning and end of the trial was always higher at the plots amended with biochar as compared to control plots (B0N0, B0N40 and B0N80); however, statistically significant effects were observed only at the beginning of the trial as well as at the end of trial in B20N40 treatments. Overall, the highest values of SOC contents were obtained at the beginning as well as at the end of the trial when 10 and 20 t/ha of biochar was applied together with 40 kg/ha N

The Effect of Fertilization on Time Domain Reflectometry Probe Measurement Accuracy in the Field Experiment in Slovakia

The paper presents evaluation of the calibration method using side-by-side direct gravimetric and indirect time domain reflectometry (TDR) for soil moisture measurements to improve TDR measurement accuracy. Measurements were carried out at the experimental site Dolná Malanta (Slovakia) in 2017. Two non-fertilized treatments – without biochar (B0 + N0) and with biochar at 20 t·ha−1 (B20 + N0) – and two fertilized treatments – with biochar at 20 t·ha−1 and N fertilizer at dosages of 160 kg·ha−1 (B20 + N160) and 240 kg·ha−1 (B20 + N240) – were used in this study. The study also investigates the relationship between both used methods of soil water content determination. A strong correlation between both methods was observed. In case of (B0 + N0); (B20 + N0); (B20 + N160); and (B20 + N240), it was 0.93; 0.97; 0.97; and 0.98, respectively. However, it is assumed that the TDR probe may show errors in the results without prior calibration. It was observed that the accuracy of TDR device was lower for fertilized treatments in contrast to the gravimetric method and non-fertilized treatments. It is assumed that the higher measurement inaccuracy might be increased by salt concentration in the soil as a result of applied N fertilizer

Is It Possible to Control the Nutrient Regime of Soils with Different Texture through Biochar Substrates?

Understanding nutrient management is essential to ensure healthy and adequate food production, especially in the context of biochar applied to soil with different soil textures. Additionally, farmers are beginning to understand the importance of nutrient management and there are still several knowledge gaps in this area. Several studies on biochar showed its positive effects, especially in sandy and nutrient-poor soils. There is still a lack of information on the impact of biochar on nutrient regimes in texturally different soils with sufficient nutrient supply and favorable soil chemistry. This study investigates the effect of two biochar substrates (a) biochar blended with farmyard manure (BS1), and (b) biochar blended with farmyard manure and digestate (BS2) applied at rates of 10 and 20 t ha−1 alone or in combination with fertilization on the changes in sorption capacity and nutrient regime of two texturally different soils: (a) sandy Arenosol, and (b) loamy Chernozem, (both in western Slovakia) which have a favorable nutrient content. The results showed that in sandy soil, the BS2 at rate of 20 t ha−1 increased the sum of basic cations (by +112%) and CEC (by +93%) compared to the control. In sandy soil, the content of total P increased by +35 and +16% in BS1 20 t ha–1 and BS2 20 t ha−1, respectively, when compared to the unfertilized control. The content of total P increased by +18% in BS1 20 t ha−1 after fertilization compared to the fertilized control. In loamy soil, the content of total P increased significantly by +53 and +14% in unfertilized treatment BS2 20 t ha−1 and fertilized treatment with BS1 at 20 t ha−1 compared to the respective controls. Available Ca increased in sandy soil by +50 and +53% in fertilized treatments with BS2 at 20 t ha−1 and BS1 at 20 t ha−1, respectively, when compared to fertilized control. In loamy soil, available Mg increased by +13% in fertilized treatment with BS1 applied at 20 t ha−1. In conclusion, BS application at a dose of 20 t ha−1 had a stronger positive effect on soil sorption parameters in sandy soil than the application dose of 10 t ha−1. The same BS application rate significantly increased total P in both soils

Biochar and Biochar with N Fertilizer Impact on Soil Physical Properties in a Silty Loam Haplic Luvisol

Recently, a lot of studies focused on the effects of biochar application to agricultural soils and its influence on the soil properties. However, only limited information is available on the simultaneous impact of N-fertilizer combined with biochar to soil physical propersies such as: soil moisture, soil temperature, bulk density and waterfilled pore space. Therefore, the aim of this study was to evaluate the changes in the soil physical properties of a silty loam Haplic Luvisol affected by the biochar application and its combination with N fertilizer during the years 2014–2016 (Experimental site of SUA-Nitra, Dolná Malanta, Slovakia). The field experiment was carried out in 2014 with different biochar application doses (0, 10 and 20 t ha-1) and different rate of N fertilization (0, 1st and 2nd level of N fertilization). The results showed that the both biochar amendment and biochar with N fertilizer increased the soil moisture in the range of 1 to 15%, on average. The higher rate of biochar resulted in higher soil moisture in all treatments with biochar in the following order B0 (14.9) B10N1 (1.47) > B20N1 (1.44) as well as B0N2 (1.51) > B10N2 (1.47) > B20N2 (1.39) during years the studied period (2014–2016)

Effects of Slow Pyrolysis Biochar on CO2 Emissions from Two Soils under Anaerobic Conditions

The amendment of sandy Haplic Arenosol and clayey loam Gleyic Fluvisol with two rates of biochar derived from the slow pyrolysis of wood feedstock was evaluated under anaerobic conditions in a 63-day laboratory experiment. The rates of biochar were 15 and 30 t ha&minus;1. Both rates of biochar were applied either with or without 90 kg ha&minus;1 of nitrogen fertilizer (NH4NO3). Soils with no amendments were used as control treatments. Our results showed that only the incorporation of 15 t ha&minus;1 of biochar, compared with the control treatment, led to a significant (p &lt; 0.05) increase in volumetric water content of the sandy soil and a significant (p &lt; 0.05) decrease in the parameters of the clayey loam soil. Increasing the biochar rate from 15 to 30 t ha&minus;1 did not result in significant changes in volumetric water content in either type of soil. In the sandy soil, CO2 emissions were significantly (p &lt; 0.05) higher in the treatments of 15 and 30 t ha&minus;1 with N fertilizer compared with the control and N fertilizer treatment. In the clayey loam soil, the combined application of both rates of biochar with N fertilizer caused no significant increase in CO2 emissions compared with the control and N fertilizer treatment. The incorporation of 30 t ha&minus;1 of biochar into the sandy soil contributed to a significant (p &lt; 0.01) increase in the cumulative CO2 flux compared with the control treatment. Application of 15 and 30 t ha&minus;1 of biochar into the clayey loam soil led, respectively, to a significant (p &lt; 0.05) and a nonsignificant increase in the cumulative CO2 fluxes compared with the control treatment