• Authors:
    • Ghosh, P. K.
    • Hazra, K. K.
    • Venkatesh, M. S.
    • Praharaj, C. S.
    • Kumar, N.
  • Source: CANADIAN JOURNAL OF SOIL SCIENCE
  • Volume: 93
  • Issue: 1
  • Year: 2013
  • Summary: As an important component of crop diversification, pulses/legumes are known to improve soil quality through their unique characteristics of biological N 2 fixation, root exudates, leaf litter fall and deep root system. Changes in the soil organic carbon pool due to the inclusion of pulses in an upland maize-based cropping system were evaluated after seven cropping cycles. The results indicate that inclusion of pulses in an upland maize-based cropping system improved the total soil organic carbon content, being greater in surface soil (0-0.2 m) and declining with soil depth. Of the four carbon fractions of total soil organic carbon ( C frac1 - C frac4 ) measured in the upland maize-based system, the most labile C fraction ( C frac1 ) was dominant. Distribution of the carbon pool varied with depth and the size of the active carbon pool was larger than that of the passive carbon pool in the surface soil, whereas in the subsurface soil depth, the size of the passive carbon pool was larger than that of the active carbon pool. Maize-wheat-mungbean and pigeonpea-wheat systems resulted in significant increases ( P≤0.05), of 11 and 10%, respectively in total soil organic carbon, and 10 and 15% in soil microbial biomass carbon, respectively, as compared with a conventional maize-wheat system. Application of crop residues along with farmyard manure at 5 Mg ha -1 and biofertilizers resulted in greater amounts of carbon fractions and higher carbon management index than in the control and the recommended inorganic (NPKSZnB) treatment, particularly in the system where pulses were included. In plots receiving organic amendments, the variable cumulative carbon input had higher correlation with total organic carbon ( R2=0.997), active pool ( R2=0.934), passive pool ( R2=0.916) and soil microbial biomass carbon ( R2=0.664). Inclusion of pulses in the maize-based system and the organic nutrient management system sequestered more organic carbon and maintained better soil health in Inceptisols of the Indo-Gangetic plains of India.
  • Authors:
    • Shirato, Y.
    • Yonemura, S.
    • Kishimoto-Mo, A. W.
    • Wagai, R.
    • Hiradate, .
    • Yagasaki, Y.
  • Source: Global Change Biology
  • Volume: 19
  • Issue: 4
  • Year: 2013
  • Summary: Temperature sensitivity of soil organic matter (SOM) decomposition may have a significant impact on global warming. Enzyme-kinetic hypothesis suggests that decomposition of low-quality substrate (recalcitrant molecular structure) requires higher activation energy and thus has greater temperature sensitivity than that of high-quality, labile substrate. Supporting evidence, however, relies largely on indirect indices of substrate quality. Furthermore, the enzyme-substrate reactions that drive decomposition may be regulated by microbial physiology and/or constrained by protective effects of soil mineral matrix. We thus tested the kinetic hypothesis by directly assessing the carbon molecular structure of low-density fraction (LF) which represents readily accessible, mineral-free SOM pool. Using five mineral soil samples of contrasting SOM concentrations, we conducted 30-days incubations (15, 25, and 35°C) to measure microbial respiration and quantified easily soluble C as well as microbial biomass C pools before and after the incubations. Carbon structure of LFs (<1.6 and 1.6-1.8 g cm -3) and bulk soil was measured by solid-state 13C-NMR. Decomposition Q10 was significantly correlated with the abundance of aromatic plus alkyl-C relative to O-alkyl-C groups in LFs but not in bulk soil fraction or with the indirect C quality indices based on microbial respiration or biomass. The warming did not significantly change the concentration of biomass C or the three types of soluble C despite two- to three-fold increase in respiration. Thus, enhanced microbial maintenance respiration (reduced C-use efficiency) especially in the soils rich in recalcitrant LF might lead to the apparent equilibrium between SOM solubilization and microbial C uptake. Our results showed physical fractionation coupled with direct assessment of molecular structure as an effective approach and supported the enzyme-kinetic interpretation of widely observed C quality-temperature relationship for short-term decomposition. Factors controlling long-term decomposition Q10 are more complex due to protective effect of mineral matrix and thus remain as a central question.
  • Authors:
    • Zhang, X-C.
    • Zheng, Z-Q.
    • Lu, Z.-Y.
    • Lu, C.-Y.
    • Sivelli,A.
    • Li, H.-W.
    • Wang, Q-J.
    • He, J
    • Li, H.
  • Source: Soil Science
  • Volume: 178
  • Issue: 1
  • Year: 2013
  • Summary: Traditional tillage (TT) in the North China Plain has maintained grain productivity in the past 50 years. Nonetheless, it has also been a major contributor to global greenhouse gas emissions, biodiversity and soil fertility loss, soil degradation, and even desertification. Permanent raised beds (PRB) have been proposed as a viable solution to achieve sustainable farming in this plain. The effects on soil chemical properties of the PRB treatment and two other treatments, namely, no-tillage and TT treatments, were measured between 2005 and 2011 in the annual double cropping regions of the North China Plain. The soil properties significantly ( P1.35) were significantly ( P<0.05) higher than those under no-tillage and TT. In the cropping zone of PRB, the bulk density was significantly reduced by 14.4%, whereas soil organic carbon, total nitrogen, phosphorus, and potassium and available nitrogen, phosphorus, and potassium in the 0- to 10-cm soil layer were significantly increased by 24.8%, 78.8%, 121.9%, 81.8%, 46.2%, 7.0%, 2.9%, respectively, in comparison with those of TT treatments. Winter wheat and summer maize yields in PRB also underwent a slight increase. Permanent raised beds seem to be an improvement on current farming systems in the North China Plain and valuable for the sustainability of farming in this region.
  • Authors:
    • Hulugalle, N. R.
  • Source: Crop and Pasture Science
  • Volume: 64
  • Issue: 8
  • Year: 2013
  • Summary: Partial mitigation of global warming caused by accelerated emissions of greenhouse gases such as carbon dioxide may be possible by storing atmospheric carbon in soils. Carbon storage is influenced by processes and properties that affect soil aggregation, such as clay and silt concentrations and mineralogy, intensity and frequency of wet/dry cycles, and microbial activity. Microbial activity, in turn, is influenced by factors such as temperature, nutrient and water availability, and residue quality. The objective of this study was to assess the influence of average annual maximum temperature on soil carbon storage in Vertosols under cotton-based farming systems. This paper reports a re-evaluation of results obtained from a series of experiments on cotton-farming systems conducted in eastern Australia between 1993 and 2010. The experimental sites were in the Macquarie and Namoi Valleys of New South Wales, and the Darling Downs and Central Highlands of Queensland. Average soil organic carbon storage in the 0-0.6m depth was highest in a Black Vertosol in Central Queensland and lowest in a Grey Vertosol that was irrigated with treated sewage effluent at Narrabri. At other sites, average values were generally comparable and ranged from 65 to 85 t C/ha. Climatic parameters such as ambient maximum temperature, T-max, and rainfall at rainfed sites (but not irrigated sites) were also related to soil organic carbon storage. At most sites, variations in carbon storage with average ambient maximum temperature were described by Gaussian models or bell-shaped curves, which are characteristic of microbial decomposition. Carbon storage occurred at peak rates only for a very limited temperature range at any one site, with these temperatures increasing with decreasing distance from the equator. The exception was a site near Narrabri that was irrigated with treated sewage effluent, where the relationship between soil organic carbon and T-max was linear. The decrease or absence of change in soil carbon storage with time reported in many Australian studies of annual cropping systems may be due to carbon storage occurring within a limited temperature range, whereas intra-seasonal average maximum temperatures can range widely. Further research needs to be conducted under field conditions to confirm these observations.
  • Authors:
    • Zhao, J.-S.
    • Hu, R.-G.
    • Iqbal, J.
    • Lin, S.
  • Source: Pedosphere
  • Volume: 23
  • Issue: 5
  • Year: 2013
  • Summary: To compare the CH4 oxidation potential among different land uses and seasons, and to observe its response to monsoon precipitation pattern and carbon and nitrogen parameters, a one-year study was conducted for different land uses (vegetable field, tilled and non-tilled orchard, upland crops and pine forest) in central subtropical China. Results showed significant differences in CH4 oxidation potential among different land uses (ranging from -3.08 to 0.36 kg CH4 ha(-1) year(-1)). Upland with corn-peanut-sweet potato rotation showed the highest CH4 emission, while pine forest showed the highest CH4 oxidation potential among all land uses. Non-tilled citrus orchard (-0.72 +/- 0.08 kg CH4 ha(-1) year(-1)) absorbed two times more CH4 than tilled citrus orchard.(-0.38 +/- 0.06 kg CH4 ha(-1) year(-1)). Irrespective of different vegetation, inorganic N fertilizer application significantly influenced CH4 fluxes across the sites (R-2 = 0.86, P = 0.002). Water-filled pore space, soil microbial biomass carbon, and dissolved nitrogen showed significant effects across different land uses (31% to 38% of variability) in one linear regression model. However, their cumulative interaction was significant for pine forest only, which might be attributed to undisturbed microbial communities legitimately responding to other variables, leading to net CH4 oxidation in the soil. These results suggested that i) natural soil condition tended to create win-win situation for CH4 oxidation, and agricultural activities could disrupt the oxidation potentials of the soils; and ii) specific management practices including but not limiting to efficient fertilizer application and utilization, water use efficiency, and less soil disruption might be required to increase the CH4 uptake from the soil.
  • Authors:
    • Managanvi, K.
    • Erayya
    • Makanur, B
    • Jagdish, J.
  • Source: Environment and Ecology
  • Volume: 31
  • Issue: 2
  • Year: 2013
  • Summary: The evidence for climate change is now considered to be unequivocal, and trends in atmospheric carbon dioxide (CO 2), temperature and sealevel rise are tracking the upper limit of model scenarios elaborated in the Fourth Assessment (AR4) undertaken by the International Panel on Climate Change (IPCC). Agriculture directly contributes almost 14% of total Green House Gas (GHG) emissions and indirectly accounts for a further 7% incurred by the conversion of forests to agriculture (mostly conversion to rangeland in the Amazon), currently at the rate of 7.3 million ha/year. It focuses on specific aspects of agriculture and agricultural water management that contribute to greenhouse gas emissions and offer prospects for mitigation. In addition to the impacts of cycles of wetting and drying, the concentration of inorganic and organic fertilizer on land with some form of water management means that the practice of irrigation has scope to mitigate GHG emissions. Global atmospheric temperature is predicted to rise by approximately 4°C by 2080, consistent with a doubling of atmospheric CO 2 concentration. Increased atmospheric concentrations of CO 2 enhance photosynthetic efficiency and reduce rates of respiration, offsetting the loss of production potential due to temperature rise. Early hopes for substantial CO 2 mitigation of production losses due to global warming have been restrained. A second line of reasoning is that by the time CO 2 levels have doubled, temperatures will also have risen by 4°C, negating any benefit.
  • Authors:
    • Govindaraj, M.
    • Prabukumar, G.
    • Arunachalam, P.
    • Kannan, P.
  • Source: African Journal of Agricultural Research
  • Volume: 8
  • Issue: 21
  • Year: 2013
  • Summary: Atmospheric rise of CO 2, N 2O and CH 4 over years, accelerated increase in global temperature, has led to uncertainty in monsoon rainfall and also leading to recurrence of drought, which in turn is severely affecting crop productivity and livelihood security of the farmers in Semi Arid Tropics. Agriculture contributes considerable amount of CO 2, N 2O and CH 4 emission into the atmosphere through different soil and crop management practices. Nevertheless agricultural activities contribute to global warming. The medium of crop production, soil is one of the major sinks of global warming gaseous and it helps to sequester more carbon and cut the N 2O emission by adopting smart soil and crop management techniques. Biochar is one of the viable organic amendments to combat climate change and sustain the soil health with sustainable crop production. It is an anaerobic pyrolysis product derived from organic sources and store carbon on a long term basis in the terrestrial ecosystem and also capable of reducing greenhouse gases (GHG) emission from soil to the atmosphere. Biochar application improved the soil health, increase the carbon capture and storage, reduce the GHG emission and enhance the crop yield with sustained soil health, which enables to meet out the food grain needs of the ever growing population.
  • Authors:
    • Yashima, M.
    • Zsuposne Olah, A.
    • Vago, I.
    • Katai, J.
    • Nagano, H.
    • Kong, Y.
    • Inubushi, K.
  • Source: Soil Science and Plant Nutrition
  • Volume: 59
  • Issue: 3
  • Year: 2013
  • Summary: The production/consumption of greenhouse gases (GHG) in soils are of great importance in global warming, but the involved soil physico-chemical and biological characteristics affecting GHG production and consumption potentials are poorly understood in different land-use types. Carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) production/consumption potentials from four land-use types and 10 soil types in central Japan and eastern Hungary, and their relationships with soil characteristics, were investigated. The average of CO2 production in Japanese soils was significantly higher than that of Hungarian soils due to the relatively higher microbial biomass carbon (MBC) content. N2O production from both countries' soils did not exhibit a significant difference. Most soils except Japanese paddy and soybean soils showed the potentials for CH4 consumption. Forest and grassland soils had relatively higher CO2 and N2O production than orchard and cropland soils for both countries. From regression analyses, it could be concluded that soil total nitrogen (TN) and ammonium-nitrogen (NH4 (+)-N) account for 40.8% and 25.5% variations of the soils' CO2 and N2O productions, respectively. The CH4 consumption was positively correlated with soil carbon/nitrogen (C/N) ratio, while soil MBC availability could account for 15% variation of CH4 consumption under aerobic conditions.
  • Authors:
    • Bonsch, M.
    • Dietrich, J. P.
    • Popp, A.
    • Lotze-Campen, H.
    • Krause, M.
  • Source: Land Use Policy
  • Volume: 30
  • Issue: 1
  • Year: 2013
  • Summary: Conservation of undisturbed natural forests, which are important for biodiversity, carbon storage, and other ecosystem services, affects agricultural production and cropland expansion. We analyze the economic impacts of undisturbed natural forest conservation programs on agriculture and the magnitude of avoided deforestation and avoided carbon emissions in the tropics. We apply a global agricultural land use model to estimate changes in agricultural production costs for the period 2015-2055. Our forest conservation scenarios reflect two different policy goals: either maximize forest carbon storage or minimize impacts on agricultural production. In all the scenarios, the economic impacts on agriculture are relatively low. Production costs would increase due to forest conservation by a maximum of 4%, predominantly driven by increased investments in agricultural productivity increase. We also show regional differences in Latin America, Sub-Saharan Africa, and Southeast Asia, due to different growth rates in food demand, land availability and crop productivity. The area of avoided deforestation does not exceed 1.5 million ha yr(-1) in the period 2015-2055, while avoided carbon emissions reach a maximum of 1.9 Gt CO2 per year. According to our results on the potential changes in agricultural production costs, undisturbed natural forest conservation appears to be a low-cost option for greenhouse gas emission reduction. (C) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Wander, M. M.
    • Dunn, J. B.
    • Mueller, S.
    • Kwon, H.-Y.
  • Source: Biomass and Bioenergy
  • Volume: 55
  • Issue: August
  • Year: 2013
  • Summary: Current estimates of life cycle greenhouse gas emissions of biofuels produced in the US can be improved by refining soil C emission factors (EF; C emissions per land area per year) for direct land use change associated with different biofuel feedstock scenarios. We developed a modeling framework to estimate these EFs at the state-level by utilizing remote sensing data, national statistics databases, and a surrogate model for CENTURY's soil organic C dynamics submodel (SCSOC). We estimated the forward change in soil C concentration within the 0-30 cm depth and computed the associated EFs for the 2011 to 2040 period for croplands, grasslands or pasture/hay, croplands/conservation reserve, and forests that were suited to produce any of four possible biofuel feedstock systems [corn (Zea Mays L)-corn, corn-corn with stover harvest, switchgrass (Panicum virgatum L), and miscanthus (Miscanthus x giganteus Greef et Deuter)]. Our results predict smaller losses or even modest gains in sequestration for corn based systems, particularly on existing croplands, than previous efforts and support assertions that production of perennial grasses will lead to negative emissions in most situations and that conversion of forest or established grasslands to biofuel production would likely produce net emissions. The proposed framework and use of the SCSOC provide transparency and relative simplicity that permit users to easily modify model inputs to inform biofuel feedstock production targets set forth by policy. (C) 2013 Elsevier Ltd. All rights reserved.