• Authors:
    • Higarashi, M. M.
    • Oliveira, P. A. V. de
    • Denega, G. L.
    • Bayer, C.
    • Silveira Nicoloso, R. da
    • Correa, J. C.
    • Santos Lopes, L. dos
  • Source: Ciencia Rural
  • Volume: 43
  • Issue: 2
  • Year: 2013
  • Summary: Assessments of soil carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2O) emissions are critical for determination of the agricultural practices' potential to mitigate global warming. This study evaluated the photoacoustic spectroscopy (PAS) for the assessment of soil greenhouse gases (GHG) fluxes in comparison to the standard gas chromatography (GC) method. Two long-term experiments with different tillage and cropping systems over a Paleudult were evaluated using static chambers. PAS measurements of CO 2 and N 2O concentrations showed good relationship and linearity (R 2=0.98 and 0.94, respectively) with GC results. However, CH 4 measurements were significantly affected by air sample moisture which interfered on CH 4 detection by PAS. Overestimation of CO 2 and N 2O concentrations in air samples determined by PAS (14.6 and 18.7%, respectively) were also related to sampling moisture. CO 2 and N 2O fluxes showed good agreement between methods (R 2=0.96 and 0.95, respectively), though PAS overestimated fluxes by 18.6 and 13.6% in relation to GC results, respectively. PAS showed good sensitivity and was able to detect CO 2 and N 2O fluxes as low as 332 mg CO 2 m -2 h -1 and 21g N 2O m -2 h -1. PAS analyzer should be detailed calibrated to reduce humidity interference on CO 2, CH 4 and N 2O concentrations measurements avoiding overestimation or erroneous determination of soil GHG fluxes.
  • Authors:
    • Robertson, G.
    • Ruan, L.
  • Source: Global Change Biology
  • Volume: 19
  • Issue: 8
  • Year: 2013
  • Summary: Around 4.4 millionha of land in USDA Conservation Reserve Program (CRP) contracts will expire between 2013 and 2018 and some will likely return to crop production. No-till (NT) management offers the potential to reduce the global warming costs of CO2, CH4, and N2O emissions during CRP conversion, but to date there have been no CRP conversion tillage comparisons. In 2009, we converted portions of three 9-21ha CRP fields in Michigan to conventional tillage (CT) or NT soybean production and reserved a fourth field for reference. Both CO2 and N2O fluxes increased following herbicide application in all converted fields, but in the CT treatment substantial and immediate N2O and CO2 fluxes occurred after tillage. For the initial 201-day conversion period, average daily N2O fluxes (g N2O-Nha(-1)d(-1)) were significantly different in the order: CT (47.5 +/- 6.31, n=6)>> NT (16.7 +/- 2.45, n=6)>> reference (2.51 +/- 0.73, n=4). Similarly, soil CO2 fluxes in CT were 1.2 times those in NT and 3.1 times those in the unconverted CRP reference field. All treatments were minor sinks for CH4 (-0.69 +/- 0.42 to -1.86 +/- 0.37g CH4-Cha(-1)d(-1)) with no significant differences among treatments. The positive global warming impact (GWI) of converted soybean fields under both CT (11.5 Mg CO(2)eha(-1)) and NT (2.87 Mg CO(2)eha(-1)) was in contrast to the negative GWI of the unconverted reference field (-3.5 Mg CO(2)eha(-1)) with on-going greenhouse gas (GHG) mitigation. N2O contributed 39.3% and 55.0% of the GWI under CT and NT systems with the remainder contributed by CO2 (60.7% and 45.0%, respectively). Including foregone mitigation, we conclude that NT management can reduce GHG costs by 60% compared to CT during initial CRP conversion.
  • Authors:
    • Dias, C.
    • La Scala, N.
    • Cerri, C.
    • Silva-Olaya, A.
    • Cerri, C.
  • Source: Environmental Research Letters
  • Volume: 8
  • Issue: 1
  • Year: 2013
  • Summary: Soil tillage and other methods of soil management may influence CO2 emissions because they accelerate the mineralization of organic carbon in the soil. This study aimed to quantify the CO2 emissions under conventional tillage (CT), minimum tillage (MT) and reduced tillage (RT) during the renovation of sugarcane fields in southern Brazil. The experiment was performed on an Oxisol in the sugarcane-planting area with mechanical harvesting. An undisturbed or no-till (NT) plot was left as a control treatment. The CO2 emissions results indicated a significant interaction (p < 0.001) between tillage method and time after tillage. By quantifying the accumulated emissions over the 44 days after soil tillage, we observed that tillage-induced emissions were higher after the CT system than the RT and MT systems, reaching 350.09 g m(-2) of CO2 in CT, and 51.7 and 5.5 g m(-2) of CO2 in RT and MT respectively. The amount of C lost in the form of CO2 due to soil tillage practices was significant and comparable to the estimated value of potential annual C accumulation resulting from changes in the harvesting system in Brazil from burning of plant residues to the adoption of green cane harvesting. The CO2 emissions in the CT system could respond to a loss of 80% of the potential soil C accumulated over one year as result of the adoption of mechanized sugarcane harvesting. Meanwhile, soil tillage during the renewal of the sugar plantation using RT and MT methods would result in low impact, with losses of 12% and 2% of the C that could potentially be accumulated during a one year period.
  • Authors:
    • Nan, Z.
    • Tang, Z.
  • Source: Mitigation and Adaptation Strategies for Global Change
  • Volume: 18
  • Issue: 7
  • Year: 2013
  • Summary: It is generally accepted that cropland soils could be managed to store significant carbon (C), however little information is available regarding the cropland soil C sequestration potential of the Loess Plateau in northern China. This study aimed to estimate the cropland soil C sequestration potential in this area using the United Nations Intergovernmental Panel on Climate Change (IPCC) method with region-specific C stock change factors. The results show that the C sequestration potential can reach 6.054 Tg C yr(-1) (1Tg = 10(12) g) in cropland soils of the Loess Plateau using techniques that are currently available (no-tillage and high residue incorporation). Although the results show a high degree of uncertainty in this estimate with 95 % confidence interval ranges from 2.623 to 11.94 Tg C yr(-1), our study suggests that cropland soil C sequestration could play a meaningful role in helping to mitigate greenhouse gas increases in the Chinese Loess Plateau.
  • Authors:
    • Liao, Y.
    • Zhang, J.
    • Lu, X. L.
    • Wen, X.
    • Tanveer, S. K.
  • Source: PLOS ONE
  • Volume: 8
  • Issue: 9
  • Year: 2013
  • Summary: A two year (2010-2012) study was conducted to assess the effects of different agronomic management practices on the emissions of CO2 from a field of non-irrigated wheat planted on China's Loess Plateau. Management practices included four tillage methods i.e. T-1: (chisel plow tillage), T-2: (zero-tillage), T-3: (rotary tillage) and T-4: (mold board plow tillage), 2 mulch levels i.e., M-0 (no corn residue mulch) and M-1 (application of corn residue mulch) and 5 levels of N fertilizer (0, 80, 160, 240, 320 kg N/ha). A factorial experiment having a strip split-split arrangement, with tillage methods in the main plots, mulch levels in the sub plots and N-fertilizer levels in the sub-sub plots with three replicates, was used for this study. The CO2 data were recorded three times per week using a portable GXH-3010E1 gas analyzer. The highest CO2 emissions were recorded following rotary tillage, compared to the lowest emissions from the zero tillage planting method. The lowest emissions were recorded at the 160 kg N/ha, fertilizer level. Higher CO2 emissions were recorded during the cropping year 2010-11 relative to the year 2011-12. During cropping year 2010-11, applications of corn residue mulch significantly increased CO2 emissions in comparison to the non-mulched treatments, and during the year 2011-12, equal emissions were recorded for both types of mulch treatments. Higher CO2 emissions were recorded immediately after the tillage operations. Different environmental factors, i.e., rain, air temperatures, soil temperatures and soil moistures, had significant effects on the CO2 emissions. We conclude that conservation tillage practices, i.e., zero tillage, the use of corn residue mulch and optimum N fertilizer use, can reduce CO2 emissions, give better yields and provide environmentally friendly options.
  • Authors:
    • Thomas,Amy R. C.
    • Bond,Alan J.
    • Hiscock,Kevin M.
  • Source: Global Change Biology Bioenergy
  • Volume: 5
  • Issue: 3
  • Year: 2013
  • Summary: Reduction in energy sector greenhouse gas GHG emissions is a key aim of European Commission plans to expand cultivation of bioenergy crops. Since agriculture makes up 1012% of anthropogenic GHG emissions, impacts of land-use change must be considered, which requires detailed understanding of specific changes to agroecosystems. The greenhouse gas (GHG) balance of perennials may differ significantly from the previous ecosystem. Net change in GHG emissions with land-use change for bioenergy may exceed avoided fossil fuel emissions, meaning that actual GHG mitigation benefits are variable. Carbon (C) and nitrogen (N) cycling are complex interlinked systems, and a change in land management may affect both differently at different sites, depending on other variables. Change in evapotranspiration with land-use change may also have significant environmental or water resource impacts at some locations. This article derives a multi-criteria based decision analysis approach to objectively identify the most appropriate assessment method of the environmental impacts of land-use change for perennial energy crops. Based on a literature review and conceptual model in support of this approach, the potential impacts of land-use change for perennial energy crops on GHG emissions and evapotranspiration were identified, as well as likely controlling variables. These findings were used to structure the decision problem and to outline model requirements. A process-based model representing the complete agroecosystem was identified as the best predictive tool, where adequate data are available. Nineteen models were assessed according to suitability criteria, to identify current model capability, based on the conceptual model, and explicit representation of processes at appropriate resolution. FASSET, ECOSSE, ANIMO, DNDC, DayCent, Expert-N, Ecosys, WNMM and CERES-NOE were identified as appropriate models, with factors such as crop, location and data availability dictating the final decision for a given project. A database to inform such decisions is included.
  • Authors:
    • Chi, S. Y.
    • Li, Z. J.
    • Li, N.
    • Wang, B. W.
    • Zhao, H. X.
    • Ning, T. Y.
    • Wang, Y.
    • Tian, S. Z.
  • Source: PLOS ONE
  • Volume: 8
  • Issue: 9
  • Year: 2013
  • Summary: Appropriate tillage plays an important role in mitigating the emissions of greenhouse gases (GHG) in regions with higher crop yields, but the emission situations of some reduced tillage systems such as subsoiling, harrow tillage and rotary tillage are not comprehensively studied. The objective of this study was to evaluate the emission characteristics of GHG (CH4 and N2O) under four reduced tillage systems from October 2007 to August 2009 based on a 10-yr tillage experiment in the North China Plain, which included no-tillage (NT) and three reduced tillage systems of subsoil tillage (ST), harrow tillage (HT) and rotary tillage (RT), with the conventional tillage (CT) as the control. The soil under the five tillage systems was an absorption sink for CH4 and an emission source for N2O. The soil temperature positive impacted on the CH4 absorption by the soils of different tillage systems, while a significant negative correlation was observed between the absorption and soil moisture. The main driving factor for increased N2O emission was not the soil temperature but the soil moisture and the content of nitrate. In the two rotation cycle of wheat-maize system (10/2007-10/2008 and 10/2008-10/2009), averaged cumulative uptake fluxes of CH4 under CT, ST, HT, RT and NT systems were approximately 1.67, 1.72, 1.63, 1.77 and 1.17 t ha(-1) year(-1), respectively, and meanwhile, approximately 4.43, 4.38, 4.47, 4.30 and 4.61 t ha(-1) year(-1) of N2O were emitted from soil of these systems, respectively. Moreover, they also gained 33.73, 34.63, 32.62, 34.56 and 27.54 t ha(-1) yields during two crop-rotation periods, respectively. Based on these comparisons, the rotary tillage and subsoiling mitigated the emissions of CH4 and N2O as well as improving crop productivity of a wheat-maize cropping system.
  • Authors:
    • Malemela, M. P.
    • Chen, F.
    • Wang, F.
    • Zhang, M.
    • Zhang, H.
  • Source: Journal of Cleaner Production
  • Volume: 54
  • Year: 2013
  • Summary: Whether farmland serves as a carbon (C) source or sink depends on the balance of soil organic carbon (SOC) sequestration and greenhouse gas (GHG) emissions. Tillage practices critically affect the SOC concentration, SOC sequestration rate and soil carbon storage (SCS). The objective of this paper is to assess the tillage effects on SOC sequestration, SCS and C footprint. Tillage experiments were established on a double cropping system of winter wheat (Triticum aestivum L) and summer corn (Zea mays L) in the North China Plain since 2001 with three treatments: no tillage (NT), rotary tillage (RT) and conventional tillage (CT). In order to assess SOC sequestration efficiency under different tillage systems, SCS, SOC sequestration rate, hidden carbon cost (HCC), indexes of sustainability (I-s) and C productivity (CP) were computed in this study. Results showed that the SCS increased with years of residue retention. The SCS attained the highest degree in 2007, which was about 25%-30% higher than that in 2004. The net SOC sequestration rate was the highest in NT and lowest in cc, while HCC was lowest under NT and highest under CT. The value of Is for CT, RT and NT treatments was 1.46, 1.79 and 1.88, respectively, and that of CP was 11.02, 12.79 and 10.57, respectively. Therefore, it can be concluded that NT provides a good option for increasing SOC sequestration for agriculture in the North China Plain.
  • Authors:
    • Bandyopadhyay, K. K.
    • Patle, G. T.
    • Singh, D. K.
  • Source: INDIAN JOURNAL OF AGRICULTURAL SCIENCES
  • Volume: 83
  • Issue: 1
  • Year: 2013
  • Summary: Global warming and its consequences are amongst the most serious problems of the present century. Increase in concentration of greenhouse gases (GHGs) in the atmosphere is major cause for global warming. Increase in global concentration of CO2 is mainly due to fossil fuel consumption, land use change and soil cultivation. Methane and N2O concentrations are increasing primarily due to dairy and agriculture. Sequestering atmospheric carbon in agricultural soils may partially offset the emission of greenhouse gases from fossil fuel consumption. Conservation agriculture helps in sequestering atmospheric carbon in soil-plant system through change in agricultural operations and management practices. Conservation tillage along with efficient management of inputs, viz. irrigation, fertilizer and pesticides facilitates carbon sequestration in soil-plant system. Land use change and conventional agricultural practices are major contributors to global annual emission of CO2. Conservation agriculture and recommended management practices (RMPs) collectively are helpful to offset part of the emissions due to unscientific agricultural practices. In India, agriculture contributes about 17 per cent of the country's total GHGs emission. An intensive agricultural practice during the post-green revolution era without caring for the environment has supposedly played a major role towards enhancement of the greenhouse gases. Due to increase in demand for food production the farmers have started growing more than one crop a year through repeated tillage operations using conventional agricultural practices. Increase in carbon emission is the major concern, which is well addressed in kyoto protocol. Nowadays, more emphasis has been given for promotion of conservation agriculture to mitigate the impact of climate change.
  • Authors:
    • Don, A.
    • Poeplau, C.
  • Source: GEODERMA
  • Volume: 192
  • Year: 2013
  • Summary: Land-use changes (WC) influence the balance of soil organic carbon (SOC) and hence may cause CO2 emissions or sequestration. In Europe there is a side by side of LUC types that lead to SOC loss or SOC accumulation. However, there is a lack of studies covering all major LUC types to investigate qualitative and quantitative LUC effects on SOC. In this study we sampled 24 paired sites in Europe to a depth of 80 cm, covering a wide range of pedo-climatic conditions and comprising the major European LUC types cropland to grassland, grassland to cropland, cropland to forest and grassland to forest To assess qualitative changes and the sensitivity of different functional SOC pools with distinct turnover times, we conducted a fractionation to isolate five different fractions of SOC. The mean SOC stock changes after LUC were 18 +/- 11 Mg ha(-1) (cropland to grassland), 21 +/- 13 Mg ha(-1) (cropland to forest), -19 +/- 7 Mg ha(-1) (grassland to cropland) and 10 +/- 7 Mg ha(-1) (grassland to forest) with the main changes occurring in the topsoil (0-30 cm depth). However, subsoil carbon stocks ( >30 cm depth) were also affected by LUC, at 19 out of 24 sites in the same direction as the topsoil. LUC promoting subsoil SOC accumulation might be a sustainable C sink Particulate organic matter (POM) was found to be most sensitive to LUC After cropland afforestation. POM accounted for 50% (9.1 +/- 2.3 Mg ha(-1)) of the sequestered carbon in 0-30 cm: after grassland afforestation POM increased on average by 5 +/- 23 Mg ha(-1), while all other fractions depleted. Thus, afforestations shift SOC from stable to labile pools. The resistant fraction comprising the so-called inert carbon was found to be only slightly less sensitive than the total SOC pool, suggesting that an inert carbon pool was not chemically extracted with NaOCl oxidation, if there is any inert carbon.