• Authors:
    • Yao, J.
    • Mahmood, Q.
    • He, M.
    • Tian, G.
    • Wu, X.
    • Pan, D.
  • Source: Journal of Food, Agriculture & Environment
  • Volume: 10
  • Issue: 3-4
  • Year: 2012
  • Summary: A better comprehension of carbon dynamics during agricultural production requires an understanding of the CO2 and CH4 fluxes from an agro-ecosystem after fertilisation. The dynamics of CO2 and CH4 fluxes for plant-soil ecosystems in a ventilated transparent greenhouse were evaluated after a pig manure compost or inorganic fertiliser application at the rate of 150 kg N ha(-1) during Brassica chinensis growth from seedling to maturity. Gas samples for the plant-soil ecosystems were collected using a static chamber approach, and the concentrations of CO2 and CH4 were determined using gas chromatography. The results showed that CO2 was fixed by the plant-soil ecosystem during Brassica chinensis growth after fertilisation and the CO2 and CH4 fluxes were not significantly different among the treatments compared with the control. The ecosystem uptake of CO2 increased with the soil temperature and the variation was in agreement with a first-order exponential curve. The temperature sensitivity of the CO2 efflux at the ecosystem level for the pig manure compost, inorganic fertiliser and control treatments were 7.97, 9.82 and 8.88, respectively. There was a positive correlation between the soil microbial biomass carbon and the CO2 uptake for both fertiliser treatments, whereas the CO2 uptake for the control treatment was increased by the soil microbial biomass nitrogen. The plant-soil ecosystems were minor CH4 sinks and sources, and the CH4 flux ranged from -5.56 to 4.23 mg CH4 m(-2)h(-1) for all of the treatments. The CH4 consumption for the pig manure compost and inorganic fertiliser treatments were negatively correlated with the soil microbial biomass nitrogen, whereas that for the control treatment showed a significant negative correlation with the soil nitrate-N. The results indicate that a plant-soil ecosystem could be a carbon sink, and that fertiliser application had no significant effects on either the CO2 or the CH4 uptake in a plant-soil ecosystem.
  • Authors:
    • Jouquet, P.
    • Doan, T.
    • Rumpel, C.
    • Ngo, P.
  • Source: Soil Biology and Biochemistry
  • Volume: 50
  • Year: 2012
  • Summary: The use of organic matter (OM) amendments is widespread in tropical countries and may be beneficial for soil carbon storage. Interactions between earthworms and OM amendments in tropical soils are largely unknown. The aim of this study was to investigate the effect of bioturbation on the quantity and chemical composition of OM in soil amended with compost and vermicompost. Our approach included comparison of soil samples amended with compost, vermicompost or chemical fertilizers in the presence or absence of earthworms during a one-year greenhouse experiment. The soils were submitted to a regular cultivation cycle. After one year, we analysed bulk samples for soil OM elemental composition and characterised its lignin and non-cellulosic carbohydrate components. Our results showed a decrease of the carbon and nitrogen content in soil amended with chemical fertilizers. Vermicompost amendment led to unchanged OC content, whereas the compost amendment increased the soils OC content compared to initial soil. The addition of earthworms reduced OC and N content in soils with organic amendments. This is in contrast to soil amended with mineral fertilizer only, where the presence of earthworms did not have any effect. Bioturbation influenced the lignin signature of the soils, and to a lesser extent the non-cellulosic carbohydrate signature. In conclusion, compost amendment combined with bioturbation influenced the quality and quantity of SOM and as result carbon storage and its biogeochemical cycling in tropical soils. Implications for soil fertility remain to be elucidated.
  • Authors:
    • Tornquist, C. G.
    • Pillar, V. D.
    • Bayer, C.
  • Source: Brazilian Journal of Biology
  • Volume: 72
  • Issue: 3
  • Year: 2012
  • Summary: The southern Brazilian grassland biome contains highly diverse natural ecosystems that have been used for centuries for grazing livestock and that also provide other important environmental services. Here we outline the main factors controlling ecosystem processes, review and discuss the available data on soil carbon stocks and greenhouse gases emissions from soils, and suggest opportunities for mitigation of climatic change. The research on carbon and greenhouse gases emissions in these ecosystems is recent and the results are still fragmented. The available data indicate that the southern Brazilian natural grassland ecosystems under adequate management contain important stocks of organic carbon in the soil, and therefore their conservation is relevant for the mitigation of climate change. Furthermore, these ecosystems show a great and rapid loss of soil organic carbon when converted to crops based on conventional tillage practices. However, in the already converted areas there is potential to mitigate greenhouse gas emissions by using cropping systems based on no soil tillage and cover-crops, and the effect is mainly related to the potential of these crop systems to accumulate soil organic carbon in the soil at rates that surpass the increased soil nitrous oxide emissions. Further modelling with these results associated with geographic information systems could generate regional estimates of carbon balance.
  • Authors:
    • Pergher, M.
    • Tomazi, M.
    • Pauletti, V.
    • de Moraes, A.
    • Zanatta, J. A.
    • Bayer, C.
    • Dieckow, J.
    • Piva, J. T.
  • Source: Plant and Soil
  • Volume: 361
  • Issue: 1-2
  • Year: 2012
  • Summary: Aims For tropical and subtropical soils, information is scarce regarding the global warming potential (GWP) of no-till (NT) agriculture systems. Soil organic carbon (OC) sequestration is promoted by NT agriculture, but this may be offset by increased nitrous oxide (N2O) emissions. We assessed the GWP of a NT as compared to conventional tillage (CT) in a subtropical Brazilian Ferralsol. Methods From September 2008 to September 2009 we used static chambers and chromatographic analyses to assess N2O and methane (CH4) soil fluxes in an area previously used for 3-4 years as a field-experiment. The winter cover crop was ryegrass (Lolium multiflorum Lam.) while in summer it was silage maize (Zea mays L.). Results The accumulated N2O emission for NT was about half that of CT (1.26 vs 2.42 kg N ha(-1) year(-1), P = 0.06). Emission peaks for N2O occurred for a month after CT, presumably induced by mineralization of residual nitrogen. In both systems, the highest N2O flux occurred after sidedressing maize with inorganic nitrogen, although the flux was lower in NT than CT (132 vs 367 mu g N m(-2) h(-1), P = 0.05), possibly because some of the sidedressed nitrogen was immobilized by ryegrass residues on the surface of the NT soil. Neither water-filled pore space (WFPS) nor inorganic nitrogen (NH (4) (+) and NO (3) (-) ) correlated with N2O fluxes, although at some specific periods relationships were observed with inorganic nitrogen. Soils subjected to CT or NT both acted as CH4 sinks during most of the experiment, although a CH4 peak in May (autumn) led to overall CH4 emissions of 1.15 kg CH4-C ha(-1) year(-1) for CT and 1.08 kg CH4-C ha(-1) year(-1) for NT (P = 0.90). The OC stock in the 0-20 cm soil layer was slightly higher for NT than for CT (67.20 vs 66.49 Mg ha(-1), P = 0.36). In the 0-100 cm layer, the OC stock was significantly higher for NT as compared to CT (234.61 vs 231.95 Mg ha(-1), P = 0.01), indicating that NT resulted in the sequestration of OC at a rate of 0.76 Mg ha(-1) year(-1). The CO2 equivalent cost of agronomic practices was similar for CT (1.72 Mg CO(2)eq ha(-1) year(-1)) and NT (1.62 Mg CO(2)eq ha(-1) year(-1)). However, NT reduced the GWP relative to CT (-0.55 vs 2.90 Mg CO(2)eq ha(-1) year(-1)), with the difference of -3.45 Mg CO(2)eq ha(-1) year(-1) (negative value implies mitigation) being driven mainly by OC sequestration. The greenhouse gas intensity (GHGI, equivalent to GWP/silage yield) was lower for NT than CT (-31.7 vs 171.1 kg CO(2)eq Mg-1 for silage maize). Conclusion As compared to CT, greenhouse gas emissions from a subtropical soil can be mitigated by NT by lowering N2O emissions and, principally, sequestration of CO2-C.
  • Authors:
    • Scheer,Clemens
    • Grace,Peter R.
    • Rowlings,David W.
    • Payero,Jose
  • Source: Plant and Soil
  • Volume: 359
  • Issue: 1-2
  • Year: 2012
  • Summary: Irrigation management affects soil water dynamics as well as the soil microbial carbon and nitrogen turnover and potentially the biosphere-atmosphere exchange of greenhouse gasses (GHG). We present a study on the effect of three irrigation treatments on the emissions of nitrous oxide (N2O) from irrigated wheat on black vertisols in South-Eastern Queensland, Australia. Soil N2O fluxes from wheat were monitored over one season with a fully automated system that measured emissions on a sub-daily basis. Measurements were taken from 3 subplots for each treatment within a randomized split-plot design. Highest N2O emissions occurred after rainfall or irrigation and the amount of irrigation water applied was found to influence the magnitude of these "emission pulses". Daily N2O emissions varied from -0.74 to 20.46 g N2O-N ha(-1) day(-1) resulting in seasonal losses ranging from 0.43 to 0.75 kg N2O-N ha(-1) season (-aEuro parts per thousand 1) for the different irrigation treatments. Emission factors (EF = proportion of N fertilizer emitted as N2O) over the wheat cropping season, uncorrected for background emissions, ranged from 0.2 to 0.4 % of total N applied for the different treatments. Highest seasonal N2O emissions were observed in the treatment with the highest irrigation intensity; however, the N2O intensity (N2O emission per crop yield) was highest in the treatment with the lowest irrigation intensity. Our data suggest that timing and amount of irrigation can effectively be used to reduce N2O losses from irrigated agricultural systems; however, in order to develop sustainable mitigation strategies the N2O intensity of a cropping system is an important concept that needs to be taken into account.
  • Authors:
    • Sauer, T.
    • Soolaneyakanahally, R.
    • de Gooijer, H.
    • Bentrup, G.
    • Schoeneberger, M.
    • Brendle, J.
    • Zhou, X.
    • Current, D.
  • Source: Journal of Soil and Water Conservation
  • Volume: 67
  • Issue: 5
  • Year: 2012
  • Authors:
    • McKone, T. E.
    • Horvath, A.
    • Santero, N. J.
    • Masanet, E.
    • Lobscheid, A. B.
    • Strogen, B.
    • Mishra, U.
    • Nazaroff, W. W.
    • Scown, C. D.
  • Source: Environmental Research Letters
  • Volume: 7
  • Issue: 1
  • Year: 2012
  • Summary: The Energy Independence and Security Act of 2007 set an annual US national production goal of 39.7 billion 1 of cellulosic ethanol by 2020. This paper explores the possibility of meeting that target by growing and processing Miscanthus x giganteus. We define and assess six production scenarios in which active cropland and/or Conservation Reserve Program land are used to grow to Miscanthus. The crop and biorefinery locations are chosen with consideration of economic, land-use, water management and greenhouse gas (GHG) emissions reduction objectives. Using lifecycle assessment, the net GHG footprint of each scenario is evaluated, providing insight into the climate costs and benefits associated with each scenario's objectives. Assuming that indirect land-use change is successfully minimized or mitigated, the results suggest two major drivers for overall GHG impact of cellulosic ethanol from Miscanthus: (a) net soil carbon sequestration or emissions during Miscanthus cultivation and (b) GHG offset credits for electricity exported by biorefineries to the grid. Without these factors, the GHG intensity of bioethanol from Miscanthus is calculated to be 11-13 g CO2-equivalent per MJ of fuel, which is 80-90% lower than gasoline. Including soil carbon sequestration and the power-offset credit results in net GHG sequestration up to 26 g CO2-equivalent per MJ of fuel.
  • Authors:
    • Prior, S.
    • Torbert, H.
    • Way, T.
    • Watts, D.
    • Smith, K.
  • Source: Pedosphere
  • Volume: 22
  • Issue: 5
  • Year: 2012
  • Summary: Tillage and fertilization practices used in row crop production are thought to alter greenhouse gas emissions from soil. This study was conducted to determine the impact of fertilizer sources, land management practices, and fertilizer placement methods on greenhouse gas (CO2, CH4, and N2O) emissions. A new prototype implement developed for applying poultry litter in subsurface bands in the soil was used in this study. The field site was located at the Sand Mountain Research and Extension Center in the Appalachian Plateau region of northeast Alabama, USA, on a Hartsells fine sandy loam (fine-loamy, siliceous, subactive, thermic Typic Hapludults). Measurements of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions followed GRACEnet (greenhouse gas reduction through agricultural carbon enhancement network) protocols to assess the effects of different tillage (conventional vs. no-tillage) and fertilizer placement (subsurface banding vs. surface application) practices in a corn (Zea mays L.) cropping system. Fertilizer sources were urea-ammonium nitrate (UAN), ammonium nitrate (AN) and poultry litter (M) applied at a rate of 170 kg ha(-1) of available N. Banding of fertilizer resulted in the greatest concentration of gaseous loss (CO2 and N2O) compared to surface applications of fertilizer. Fertilizer banding increased CO2 and N2O loss on various sampling days throughout the season with poultry litter banding emitting more gas than UAN banding. Conventional tillage practices also resulted in a higher concentration of CO2 and N2O loss when evaluating tillage by sampling day. Throughout the course of this study, CH4 flux was not affected by tillage, fertilizer source, or fertilizer placement method. These results suggest that poultry litter use and banding practices have the potential to increase greenhouse gas emissions.
  • Authors:
    • Xiong, Z.
    • Zhang, X.
    • Liu, Y.
    • Pan, X.
    • Wang, J.
  • Source: Plant and Soil
  • Volume: 360
  • Issue: 1-2
  • Year: 2012
  • Summary: Worldwide, there is an increasing interest in using biochar in agriculture to help mitigate global warming and improve crop productivity. The effects of biochar on greenhouse gas (GHG) emissions and rice and wheat yields were assessed using outdoor pot experiments in two different soils (upland soil vs. paddy soil) and an aerobic incubation experiment in the paddy soil. Biochar addition to the upland soil increased methane (CH4) emissions by 37 % during the rice season, while it had no effect on CH4 emissions during the wheat season. Biochar amendment decreased nitrous oxide (N2O) emissions up to 54 % and 53 % during the rice and wheat seasons, respectively, but had no effect on the ecosystem respiration in either crop season. In the aerobic incubation experiment, biochar addition significantly decreased N2O emissions and increased carbon dioxide (CO2) emissions from the paddy soil (P < 0.01) without urea nitrogen. Biochar addition increased grain yield and biomass if applied with nitrogen fertilizer. Averaged over the two soils, biochar amendments increased the production of rice and wheat by 12 % and 17 %, respectively, and these increases can be partly attributed to the increases in soil nitrate retention. Our results demonstrated that although biochar increased the global warming potential at high nitrogen fertilizer application, biochar incorporation significantly decreased N2O emissions while promoting crop production.
  • Authors:
    • Grignani, C.
    • Sacco, D.
    • Monaco, S.
    • Zavattaro, L.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 147
  • Year: 2012
  • Summary: Maize (Zea mays, L) is not only the main crop in the intensively cultivated Po Plain (Northern Italy), but also the one that produces the largest N Surplus. This study is based on experimental data from the Tetto Frati long-term trial (Turin, NW Italy) to demonstrate that the impact on soil and water quality of high-yielding, maize-based cropping systems can be reduced through proper management. Nitrogen use efficiency and loss indicators were calculated and compared among various management options: (i) maize monoculture at high N fertilizer rates for grain production (most widespread management), (ii) entire plant (with straw) harvest, (iii) double-cropping system with a winter crop, (iv) maize-grass ley rotation, and (v) change in fertilizer type. The entire maize plant removal reduced N leaching by 10-20%; however, carbon sequestration was also reduced. A maize-Italian ryegrass double cropping system improved the efficiency of organic fertilizers, and reduced leaching by 25-40% relative to monoculture. A rotation with grass ley reduced N impact only when fertilized with urea, and not when organic fertilizers were used. Urea, slurry, and farmyard manure were equally utilized by the crop; if distributed and incorporated just before sowing, both organic fertilizers built up the soil organic matter content and reduced N leaching by 20-50% with respect to urea. This study has shown that farmers in NW Italy have several opportunities to continue cultivate maize thus accomplishing agri-environmental legislation.