• Authors:
    • Samarasinghe, S.
    • Safa, M.
  • Source: Environmental Pollution
  • Volume: 171
  • Issue: December
  • Year: 2012
  • Summary: This review paper concentrates on carbon dioxide emissions, discussing its agricultural sources and the possibilities for minimizing emissions from these sources in wheat production in Canterbury, New Zealand. This study was conducted over 35,300 ha of irrigated and dryland wheat fields in Canterbury. Total CO2 emissions were 1032 kg CO2/ha in wheat production. Around 52% of the total CO2 emissions were released from fertilizer use and around 20% were released from fuel used in wheat production. Nitrogen fertilizers were responsible for 48% (499 kg CO2/ha) of CO2 emissions. The link between nitrogen consumption, CO2 emissions and crop production showed that reducing the CO2 emissions would decrease crop production and net financial benefits to farmers. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Juszczak, R.
    • Sakowska, K.
    • Uzdzicka, B.
    • Olejnik, J.
  • Source: Woda Srodowisko Obszary Wiejskie
  • Volume: 12
  • Issue: 38
  • Year: 2012
  • Summary: One of the methods to study the exchange of mass and energy between the atmosphere and the surface of various terrestrial ecosystems is direct measurement of the fluxes of greenhouse gases. Particular attention is focussed on carbon dioxide whose concentration in the atmosphere dramatically increases [Urbaniak 2006]. The paper presents results of the measurements of carbon dioxide exchange conducted on 29th of June 2011 on three experimental plots (alfalfa, winter wheat and potato crops) situated in Agricultural Experimental Station in Brody (Wielkopolskie Province) and modeled values of ecosystem respiration ( Reco ), net ecosystem exchange ( NEE) and gross ecosystem production ( GEP). Measurements were carried out by means of closed dynamic chamber system. Reco measured on 29th of June 2011 ranged from 3.61 to 16.62 mol CO 2.m -2.s -1 and measured NEE - from 4.22 to -24.08 mol CO 2.m -2.s -1. Modeled values of the ecosystem respiration ( Reco ) for particular crops obtained with the LLOYD and Taylor [1994] function did not differ from measured values by more than 4% on average. The results of NEE modeling indicate that selected model [Michaelis, Menten 1913] worked well for sites with alfalfa and winter wheat crops (mean absolute percentage error - MAPE was 25.0 and 7.3%, respectively). NEE predictions for the site with potato crop differed largely ( MAPE=98.5%) from measured values and hence there is a need for looking for a model that would consider, apart from PPFD, also other environmental factors driving photosynthesis.
  • 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:
    • Fiener, P.
    • Reichenau, T. G.
    • Schmidt, M.
    • Schneider, K.
  • Source: Agricultural and Forest Meteorology
  • Volume: 165
  • Issue: November
  • Year: 2012
  • Summary: Arable land occupies large areas of global land surface and hence plays an important role in the terrestrial carbon cycle. Therefore agro-ecosystems show a high potential of mitigating greenhouse gas emissions while optimizing agricultural management. Hence, there is a growing interest in analyzing and understanding carbon fluxes from arable land as affected by regional environmental as well as management conditions. The major goal of this study is to use a two year data set of eddy covariance measurements (October 2007 to October 2009) on a winter wheat field located in Western Germany to assess the seasonal and inter-annual variability of carbon fluxes as affected by meteorological variables and land management. During the study period, which was comprised of two full growing seasons, eddy covariance measurements together with measurements of various soil, plant, and meteorological data were performed. Flux partitioning and gap filling methods including uncertainty estimates were applied to derive complete time series of net ecosystem exchange (NEE), gross primary production (GPP), and ecosystem respiration (R-eco). Despite different management dates and slightly different meteorological conditions, annual NEE resulted in 270 g C m(-2) in both years. Although the period from sowing to harvesting was more than 20 days shorter in the first year, due to the later start of senescence, GPP was higher by 220 g C m(-2). In the annual carbon budget this was compensated by a stronger heterotrophic respiration after the harvest of sugar beet grown on the field before the study period. Taking into account the carbon losses due to removal of biomass during harvest, the winter wheat field acts as a carbon source with respective net biome productivities (NBP) of 246 and 201 g C m(-2) a(-1). To complete the carbon balance, releases due to energy consumption associated with crop production are taken into account. However, the relatively large carbon loss was probably, to a large extent, compensated by carbon input from plant residues left on the field after preceding sugar beet harvest. This underlines the importance of multi-annual measurements taking full crop rotations into account. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Joergensen, R. G.
    • Schweinsberg-Mickan, M. S. Z.
    • Mueller, T.
  • Source: Journal of Plant Nutrition and Soil Science
  • Volume: 175
  • Issue: 5
  • Year: 2012
  • Summary: A greenhouse rhizobox experiment was carried out to investigate the fate and turnover of 13C- and 15N-labeled rhizodeposits within a rhizosphere gradient from 08?mm distance to the roots of wheat. Rhizosphere soil layers from 01, 12, 23, 34, 46, and 68?mm distance to separated roots were investigated in an incubation experiment (42 d, 15 degrees C) for changes in total C and N and that derived from rhizodeposition in total soil, in soil microbial biomass, and in the 0.05 M K2SO4extractable soil fraction. CO2-C respiration in total and that derived from rhizodeposition were measured from the incubated rhizosphere soil samples. Rhizodeposition C was detected in rhizosphere soil up to 46?mm distance from the separated roots. Rhizodeposition N was only detected in the rhizosphere soils up to 34?mm distance from the roots. Microbial biomass C and N was increased with increasing proximity to the separated roots. Beside 13C and 15N derived from rhizodeposits, unlabeled soil C and N (native SOM) were incorporated into the growing microbial biomass towards the roots, indicating a distinct acceleration of soil organic matter (SOM) decomposition and N immobilization into the growing microbial biomass, even under the competition of plant growth. During the soil incubation, microbial biomass C and N decreased in all samples. Any decrease in microbial biomass C and N in the incubated rhizosphere soil layers is attributed mainly to a decrease of unlabeled (native) C and N, whereas the main portion of previously incorporated rhizodeposition C and N during the plant growth period remained immobilized in the microbial biomass during the incubation. Mineralization of native SOM C and N was enhanced within the entire investigated rhizosphere gradient. The results indicate complex interactions between substrate input derived from rhizodeposition, microbial growth, and accelerated C and N turnover, including the decomposition of native SOM (i.e., rhizosphere priming effects) at a high spatial resolution from the roots.
  • Authors:
    • Bakken, L.
    • Budai, A.
    • Chen, R.
    • Senbayram, M.
    • Dittert, K.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 147
  • Issue: January
  • Year: 2012
  • Summary: Amending agricultural soils with organic residues is frequently recommended to improve soil fertility and to sequester carbon for counteracting global warming. However, such amendments will enhance microbial respiration, hence denitrification. Therefore, the assessment of effects on global warming must take N2O emission and the N2O/(N2O + N-2) product ratio of denitrification into account. There are some indications that the product ratio of denitrification is positively correlated with the ratio of available NO3- and available organic C in soils, but more research is needed to unravel quantitative relationships in well defined experiments. We conducted two laboratory incubation experiments, with the objective (i) to test the impact of the application of various N containing organic substrates including biogas residue on the denitrification rate and on N2O emission, and (ii) to investigate the effect of various NO3- concentrations on the denitrification rate and the N2O/(N2O + N-2) product ratio under standardized anoxic conditions in soils collected from long-term organic or inorganic fertilizer plots. In experiment 1, we found that biogas residue was more recalcitrant than maize straw, despite a high concentration of soluble organic C. High respiration (treatments with maize straw and sucrose) resulted in a transient peak in N2O emission, declining rapidly towards zero as nitrate concentrations reached less than 20 mg NO3--N kg(-1) dry soil. Application of biogas residue had a more moderate effect on soil respiration and denitrification, and resulted in a more long lasting peak in N2O emission. The results were interpreted as a result of a gradual increase in the relative activity of N2O reductase (thus lowering of the N2O/(N2O + N-2) product ratio of denitrification) throughout the incubation, most likely controlled by concentration of available NO3- in soil. In the second experiment, we found low N2O/(N2O N-2) product ratios for the treatment where NO3- concentrations were = 10 mM NO3-, and the ratios were remarkably independent of the soil's fertilizer history. We conclude that (i) in N-fertilized agricultural soils, application of organic matter with high contents of labile C may trigger denitrification-derived N2O emission whereas (ii) in soils with low NO3- contents such application may substantially lower the N2O/(N2O + N-2) product ratio and hence N2O emission. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Walker, M. B.
    • Faber, A.
    • Syp, A.
  • Source: Journal of Food, Agriculture & Environment
  • Volume: 10
  • Issue: 3-4
  • Year: 2012
  • Summary: In this paper, simulations with a Denitrification -Decomposition (DNDC) model were used to evaluate the impact of different management options on carbon (C) sequestration and emission of greenhouse gases: methane (CH 4) and nitrous oxide (N2O). Two cropping systems were analyzed. The first included potato, winter wheat, spring barley and forage maize (P-W-B-M). The second included potato, winter wheat, spring barley with clover and grass mixture (P-W-B-C). In both cropping systems, different farmyard manure (FYM) rates were applied. The application of additional nitrogen (N) using FYM increased the C sequestration, as well as N2O emissions and had a little effect on CH 4 uptake. An estimate into the average annual increases in N2O emissions, which were converted into carbon dioxide (CO2) equivalent emissions with 100-year global warming potential (GWP) multipliers, were offset by 56-144% of the C sequestration, depending on the management option. After 16 years of the experiment, the accumulation of C and N per hectare increased in the soil organic matter (SOM) pool. In P-W-B-M rotation, with manure applied at 325 kg N ha(-1), the accumulation of C increased to 5,760 and N 585 kg ha(-1), respectively. In P-W-B-C rotation, where a higher rate of manure was applied, the increase of C was at 10,796 and N 740 kg ha(-1). The highest influence in the rise of C and N accumulation was in humates. The high value of C sequestration in soil outweighs the emissions of N2O. In P-W-B-M rotations, the rate of applied FYM switched its average annual net GWP balance from net losses to a net sink. In P-W-B-C rotations, the applied FYM increased the annual rate of GHG emissions by 3%. The average annual N2O emissions increased by 44% under P-W-B-C rotation and by 142% under P-W-B-M rotations. Increases in the soil organic carbon (SOC) were by 234% and 408%, respectively, for P-W-B-C and P-W-B-M rotations. Our study showed that usage of FYM should be managed correctly, because applications at high rates have a negative impact on environment.
  • Authors:
    • Kuzyakov, Y.
    • Li, X.
    • Marschner, P.
    • Guo, J.
    • Fan, M.
    • Tian, J.
  • Source: European Journal of Soil Biology
  • Volume: 52
  • Issue: September–Octobe
  • Year: 2012
  • Summary: In the last three decades there has been a major shift in China's agriculture with the conversion from cereal fields to vegetable production, however little is known about the impact of this land use change on labile soil carbon and microbial community structure. We conducted a study to characterize dissolved organic carbon (DOC) and soil microbial community by comparing greenhouse vegetable fields with contrasting management intensity and adjacent cereal fields (wheat maize rotation) in Shouguang and Quzhou in North China. Compared with cereal fields, greenhouse vegetable cultivation increased soil organic carbon (SOC) and total nitrogen (TN), while it decreased the soil pH, particularly at the high-intensity site. The DOC concentration was significantly higher in greenhouse vegetable fields than in cereal fields, whereas DOC composition differed between greenhouse vegetable fields and cereal fields only at high management intensity. Chemical fractionation indicated that DOC from greenhouse vegetable fields with high management intensity was less decomposed than DOC from cereal fields, because the percentage of hydrophobic acid (HOA) as DOC was higher in vegetable fields. Vegetable production significantly changed the microbial community structure in comparison to cereal fields: high-intensity management increased total bacteria, G (+) bacteria and fungi, while low-intensity decreased fungi and increased bacteria-to-fungi ratio. The main factor affecting microbial community structure was soil pH in this study, accounting for 24% of the differences. (C) 2012 Elsevier Masson SAS. All rights reserved.
  • Authors:
    • Chi, S.
    • Li, Z.
    • Han, H.
    • Li, N.
    • Wang, B.
    • Zhao, H.
    • Ning, T.
    • Tian, S.
  • Source: Web Of Knowledge
  • Volume: 7
  • Issue: 12
  • Year: 2012
  • Summary: The objective of this study was to quantify soil methane (CH4) and nitrous oxide (N2O) emissions when converting from minimum and no-tillage systems to subsoiling (tilled soil to a depth of 40 cm to 45 cm) in the North China Plain. The relationships between CH4 and N2O flux and soil temperature, moisture, NH4+-N, organic carbon (SOC) and pH were investigated over 18 months using a split-plot design. The soil absorption of CH4 appeared to increase after conversion from no-tillage (NT) to subsoiling (NTS), from harrow tillage (HT) to subsoiling (HTS) and from rotary tillage (RT) to subsoiling (RTS). N2O emissions also increased after conversion. Furthermore, after conversion to subsoiling, the combined global warming potential (GWP) of CH4 and N2O increased by approximately 0.05 kg CO2 ha(-1) for HTS, 0.02 kg CO2 ha(-1) for RTS and 0.23 kg CO2 ha(-1) for NTS. Soil temperature, moisture, SOC, NH4+-N and pH also changed after conversion to subsoiling. These changes were correlated with CH4 uptake and N2O emissions. However, there was no significant correlation between N2O emissions and soil temperature in this study. The grain yields of wheat improved after conversion to subsoiling. Under HTS, RTS and NTS, the average grain yield was elevated by approximately 42.5%, 27.8% and 60.3% respectively. Our findings indicate that RTS and HTS would be ideal rotation tillage systems to balance GWP decreases and grain yield improvements in the North China Plain region. Citation: Tian S, Ning T, Zhao H, Wang B, Li N, et al. (2012) Response of CH4 and N2O Emissions and Wheat Yields to Tillage Method Changes in the North China Plain. PLoS ONE 7(12): e51206. doi:10.1371/journal.pone.0051206
  • 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.