• Authors:
    • Saad, A. A.
    • Das, S.
    • Sharma, A. R.
    • Bhattacharyya, R.
    • Das, T. K.
    • Pathak, H.
  • Source: European Journal of Agronomy
  • Volume: 51
  • Year: 2013
  • Summary: Sequestration of C in arable soils has been considered as a potential mechanism to mitigate the elevated levels of atmospheric greenhouse gases. We evaluated impacts of conservation agriculture on change in total soil organic C (SOC) and relationship between C addition and storage in a sandy loam soil of the Indo-Gangetic Plains. Cotton (Gossypium hirsutum L.) and wheat (Triticum aestivum L.) crops were grown during the first three years (2008-2011) and in the last year, maize (Zea mays L), wheat and green gram (Vigna radiate L.) were cultivated. Results indicate the plots under zero tillage with bed planting (ZT-B) and zero tillage with flat planting (ZT-F) had nearly 28 and 26% higher total SOC stock compared with conventional tillage and bed planting (CT-B) (similar to 5.5 Mg ha(-1)) in the 0-5 cm soil layer. Plots under ZT-B and ZT-F contained higher total SOC stocks in the 0-5 and 5-15 cm soil layers than CT-B plots. Although there were significant variations in total SOC stocks in the surface layers, SOC stocks were similar under all treatments in the 0-30 cm soil layer. Residue management had no impact on SOC stocks in all layers, despite plots under cotton/maize + wheat residue (C/M+W RES) contained similar to 13% higher total SOC concentration than no residue treated plots (N RES; similar to 7.6 g kg(-1)) in the 0-5 cm layer. Hence, tillage and residue management interaction effects were not significant. Although CT-B and ZT-F had similar maize aboveground biomass yields, CT-F treated plots yielded 16% less maize biomass than CT-B plots. However, both wheat and green gram (2012) yields were not affected by tillage. Plots under C/M + W RES had similar to 17, 13, 13 and 32% higher mean cotton, maize, wheat and green gram aboveground biomass yields than N RES plots, yielding similar to 16% higher estimated root (and rhizodeposition) C input in the 0-30 cm soil layer than N RES plots. About 9.3% of the gross C input contributed towards the increase in SOC content under the residue treated plots. However, similar to 7.6 and 10.2% of the gross C input contributed towards the increase in SOC content under CT and if, respectively. Thus, both ZT and partial or full residue retention is recommended for higher soil C retention and sustained crop productivity. (c) Elsevier B.V. All rights reserved.
  • Authors:
    • Borgesen, C. D.
    • Kristensen, I. T.
    • Hermansen, J. E.
    • Olesen, J. E.
    • Elsgaard, L.
  • Source: Acta Agriculturae Scandinavica, Section B — Soil & Plant Science
  • Volume: 63
  • Issue: 3
  • Year: 2013
  • Summary: Biofuels from bioenergy crops may substitute a significant part of fossil fuels in the transport sector where, e.g., the European Union has set a target of using 10% renewable energy by 2020. Savings of greenhouse gas emissions by biofuels vary according to cropping systems and are influenced by such regional factors as soil conditions, climate and input of agrochemicals. Here we analysed at a regional scale the greenhouse gas (GHG) emissions associated with cultivation of winter wheat for bioethanol and winter rapeseed for rapeseed methyl ester (RME) under Danish conditions. Emitted CO2 equivalents (CO2eq) were quantified from the footprints of CO2, CH4 and N2O associated with cultivation and the emissions were allocated between biofuel energy and co-products. Greenhouse gas emission at the national level (Denmark) was estimated to 22.1 g CO2eq MJ(1) ethanol for winter wheat and 26.0 g CO2eq MJ(1) RME for winter rapeseed. Results at the regional level (level 2 according to the Nomenclature of Territorial Units for Statistics [NUTS]) ranged from 20.0 to 23.9 g CO2eq MJ(1) ethanol and from 23.5 to 27.6 g CO2eq MJ(1) RME. Thus, at the regional level emission results varied by up to 20%. Differences in area-based emissions were only 4% reflecting the importance of regional variation in yields for the emission result. Fertilizer nitrogen production and direct emissions of soil N2O were major contributors to the final emission result and sensitivity analyses showed that the emission result depended to a large extent on the uncertainty ranges assumed for soil N2O emissions. Improvement of greenhouse gas balances could be pursued, e.g., by growing dedicated varieties for energy purposes. However, in a wider perspective, land-use change of native ecosystems to bioenergy cropping systems could compromise the CO2 savings of bioenergy production and challenge the targets set for biofuel production.
  • Authors:
    • Ahmad, W.
    • Biswas, W. K.
    • Engelbrecht, D.
  • Source: Journal of Cleaner Production
  • Volume: 57
  • Year: 2013
  • Summary: The International Panel on Climate Change (IPCC) predicts an increase of 0.2 degrees C per decade for the next two decades in global temperatures and a rise of between 1.5 and 4.5 degrees C by the year 2100. Related to the increase in world temperatures is the increase in Greenhouse Gases (GHGs) which are primarily made up of carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and fluorinated gases. In 2004, the GHGs from agriculture contributed 14% of the overall global GHGs made up mainly of methane (CH4) and nitrous oxide (N2O) emissions. In Australia, the dominant source of CH4 and N2O emissions for the year ending June 2012 was found to be from the agricultural sector. With the recent introduction of the Clean Energy Act 2011, the agricultural sector of Australia is expected to develop appropriate GHG mitigation strategies to maintain and improve its competitiveness in the green commodity market. This paper proposes the use of Integrated Spatial Technologies (IST) framework by linking Life Cycle Assessment (LCA), Remote Sensing (RS) and Geographical Information Systems (GIS). The IST approach also integrates and highlights the use of Cleaner Production (CP) strategies for the formulation and application of cost-effective GHG mitigation options for grain production in Western Australia (WA). In this study, the IST framework was tested using data from an existing study (the baseline study) and two mitigation options. The analysis results revealed production and use of fertiliser as the "hotspot", and for mitigation purposes was replaced with pig manure in option I, whereas option 2 emphasised crop rotation system/s.
  • Authors:
    • Cao, Y.
    • Drake, B.
    • Elliott, J.
    • Firbank, L. G.
    • Gooday, R.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 173
  • Year: 2013
  • Summary: Several influential reports have suggested that one of the most appropriate responses to expected food shortages and ongoing environmental degradation is sustainable intensification, i.e. the increase of food production with at worst no increase in environmental harm, and ideally environmental benefit. Here we sought evidence of sustainable intensification among British farmers by selecting innovative arable, dairy, mixed and upland farms and analysing their own data on yields, inputs and land use and management for 2006 and 2011. The evidence was obtained by interview, and was interpreted in terms of the ecosystem services of food production (GJ ha(-1), where area took into account estimated area to grow any imported animal feeds), regulation of climate, air and water quality (modelled emissions of GHGs (CO(2)e ha(-1)), ammonia (kg ha(-1)) and nitrate loss (kg ha(-1))) and biodiversity (using an index based on the presence of habitats and management). Several farms have increased both food production and other ecosystem services over this time by increasing yields, using resources more efficiently and/or enhancing biodiversity, and sometimes by reducing livestock numbers and increasing cropping. The motivation has been to improve farm profitability through increasing food production, reducing input costs and accessing public payments through agri-environment schemes and generating renewable energy. Such sustainable intensification was not achieved by farmers who increased meat or milk yields. Sustainable intensification can be achieved when the correct drivers are in place to influence the actions of individual farmers. Also, it is possible to indicate sustainable intensification by using a small number of high-level indicators derived from data that farmers already hold, though such an approach may not capture the impacts of farmer innovative practices.
  • Authors:
    • Elanchezhian, R.
    • Chhabra, V.
    • Biswas, S.
    • Haris, A. V. A.
    • Bhatt, B. P.
  • Source: CURRENT SCIENCE
  • Volume: 104
  • Issue: 2
  • Year: 2013
  • Summary: Accumulation of greenhouse gases (GHGs) in the atmosphere has exposed us to the potential warming and its adverse effects on agriculture. The present study deals with the impact of climate change on winter wheat and maize using the Infocrop model. Simulation studies were performed for different time-periods using HADCM3 factors at four centres located in three different agroecological zones, with prevalent management practices. The results showed that under changed climate, wheat yield decreased whereas the yield of winter maize increased due to warmer winters and enhanced CO2 compared to baseline. Duration of both the crops has decreased owing to the higher temperatures during the growing period. The increase in yield of winter maize points to the suitability of the region for its cultivation in future. Further, increase in maize cultivation in locations with poor wheat yield could well be considered as an adaptation option.
  • Authors:
    • Partington, D. L.
    • Phelan, A. J.
    • Zollinger, R. P.
    • Fogarty, K. M.
    • Armstrong, R. D.
    • Hill, P. A.
    • Officer, S. J.
    • Harris, R. H.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 95
  • Issue: 2
  • Year: 2013
  • Summary: Nitrous oxide (N2O) is a potent greenhouse gas released from high rainfall cropping soils, but the role of management in its abatement remains unclear in these environments. To quantify the relative influence of management, nitrogen (N) fertiliser and soil nitrification inhibitor was applied to separate but paired raised bed and conventionally flat field experiments in south west Victoria, to measure emissions and income from wheat and canola planted 2 and 3 years after conversion from a long-term pasture. Management included four different rates of N fertiliser, top-dressed with and without the nitrification inhibitor Dicyandiamide (DCD), which was applied in solution to the soil in the second year of experimentation. Crop biomass, grain yield, soil mineral N, soil temperature and soil water and N2O flux were measured. Static chamber methodology was used to identify relative differences in N2O loss between management. In the second crop (wheat) following conversion, N2O losses were up to 72 % lower (P < 0.05) in the furrows, receiving the lower rate of N fertiliser compared with the highest rate, with less frequent reductions observed in the third crop (canola); losses of N2O from the beds was unaffected by N rate, perhaps from nitrate leakage into the adjacent furrow of the raised bed experiment. On the nearby flat experiment, nitrate leaching may have diminished the effects of N rate and DCD on N2O flux. Furthermore the extra N did not significantly increase grain yield in either the wheat or canola crops on both experiments. The application of DCD in the canola crop temporarily reduced (P < 0.05) N2O production by up to 84 % from the beds, 83 % in the adjacent furrows and 75 % on the flat experiment. Grain yield was not significantly (P < 0.001) affected however, canola income was reduced by $1407/ha and $1252/ha, compared with no addition of inhibitor on the respective bed and flat experiments. Although N2O fluxes are driven by environmental episodic events, management will play a role in N2O abatement. However, DCD currently appears economically unfeasible and matching N fertiliser supply to meet crop demand appears a better option for minimising N2O losses from high rainfall cropping systems.
  • Authors:
    • Huang, B.-X.
    • Christie, P.
    • Oenema, O.
    • Gao, B.
    • Ju, X.-T.
    • Su, F.
    • Hu, X.-K.
    • Jiang, R.-F.
    • Zhang, F.-S.
  • Source: Environmental Pollution
  • Volume: 176
  • Year: 2013
  • Summary: Here, we report on a two-years field experiment aimed at the quantification of the emissions of nitrous oxide (N2O) and methane (CH4) from the dominant wheat maize double cropping system in North China Plain. The experiment had 6 different fertilization strategies, including a control treatment, recommended fertilization, with and without straw and manure applications, and nitrification inhibitor and slow release urea. Application of N fertilizer slightly decreased CH4 uptake by soil. Direct N2O emissions derived from recommended urea application was 0.39% of the annual urea-N input. Both straw and manure had relatively low N2O emissions factors. Slow release urea had a relatively high emission factor. Addition of nitrification inhibitor reduced N2O emission by 55%. We conclude that use of nitrification inhibitors is a promising strategy for N2O mitigation for the intensive wheat maize double cropping systems.
  • Authors:
    • Li, C.
    • Yang, Y.
    • Li, H.
    • Shen, S.
    • Chen, S.
    • Cui, H.
    • Hu, Z.
  • Source: Water, Air, & Soil Pollution
  • Volume: 224
  • Issue: 1
  • Year: 2013
  • Summary: Field experiments were conducted in the 2008-2009 soybean and winter wheat-growing seasons to assess soil respiration (SR) and nitrous oxide (N2O) emission as affected by enhanced UV-B radiation and straw incorporation. The SR rate was measured using a soil CO2 flux system; the N2O flux was measured using a static chamber-gas chromatograph technique. The results showed that in the soybean and winter wheat-growing seasons, enhanced UV-B radiation significantly decreased the SR rates and that straw incorporation increased the SR rates compared to the control treatment. The combined treatment of UV-B and straw incorporation had no obvious influence on the SR rates. Enhanced UV-B radiation, straw incorporation, and the combination treatment increased the temperature sensitivity of SR in the soybean-growing season. The study also showed that N2O emissions were reduced by enhanced UV-B radiation and that straw incorporation had no significant effects on the mean N2O emission fluxes in the soybean and winter wheat-growing seasons. Our findings suggest that enhanced UV-B radiation may lead to a decrease in SR and in N2O emissions, straw incorporation may increase SR, and the combined treatment may have no significant influence on SR and N2O emissions from soybean-winter wheat rotation systems.
  • Authors:
    • Jat, M. L.
    • Jat, H. S.
    • Saharawat, Y. S.
    • Kumar, A.
    • Sharma, P. C.
    • Singh, M.
    • Kumar, V.
    • Gathala, M. K.
    • Humphreys, E.
    • Sharma, D. K.
    • Ladha, J. K.
    • Sharma, S.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 177
  • Year: 2013
  • Summary: Increasing scarcity of resources (labour, water, and energy) and cost of production, along with climate variability, are major challenges for the sustainability of rice-wheat system in the northwesten Indo-Gangetic Plains (IGP). We hypothesized that adopting the principles of conservation agriculture together with best crop management practices would improve system productivity and overall efficiency, resulting in a higher profitability. To test this hypothesis, we evaluated the performance of four cropping system scenarios (treatments), which were designed to be adapted to current and future drivers of agricultural changes. The treatments including farmers practices varied in tillage and crop establishment methods, residue management, crop sequence, and crop management. Zero-tillage direct-seeded rice (ZT-DSR) with residue retention and best management practices provided equivalent or higher yield and 30-50% lower irrigation water use than those of farmer-managed puddled transplanted rice (CT-TPR). Overall, net economic returns increased up to 79% with a net reduction in production cost of up to US$ 55 ha -1 in ZT-DSR than CT-TPR. Substituting rice with ZT maize was equally profitable but with 88-95% less irrigation water use. Avoiding puddling in rice and dry tillage in maize with residue retention increased yield (by 0.5-1.2 t ha -1) and net economic returns of the succeeding wheat crop. Inclusion of mungbean in the rotation further increased system productivity and economic returns. In summary, our initial results of 2-year field study showed positive effects of CA-based improved management practices on yield and system efficiencies with greater benefits in the second year. There is a need of longer term monitoring to quantify cumulative effects of various interventions and to eventually make recommendations for wider dissemination.
  • Authors:
    • Hatfield, J. L.
    • Hanan, N. P.
    • Glenn, A. J.
    • Fischer, M. L.
    • Burba, G. G.
    • Billesbach, D. P.
    • Bernacchi, C. J.
    • Baron, V. S.
    • Meyers, T. P.
    • Tieszen, L. L.
    • Wylie, B. K.
    • Gilmanov, T. G.
    • Heuer, M. W.
    • Hollinger, S. E.
    • Howard, D. M.
    • Matamala, R.
    • Prueger, J. H.
    • Tenuta, M.
    • Young, D. G.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 164
  • Year: 2013
  • Summary: We analyzed net CO 2 exchange data from 13 flux tower sites with 27 site-years of measurements over maize and wheat fields across midcontinent North America. A numerically robust "light-soil temperature-VPD"-based method was used to partition the data into photosynthetic assimilation and ecosystem respiration components. Year-round ecosystem-scale ecophysiological parameters of apparent quantum yield, photosynthetic capacity, convexity of the light response, respiration rate parameters, ecological light-use efficiency, and the curvature of the VPD-response of photosynthesis for maize and wheat crops were numerically identified and interpolated/extrapolated. This allowed us to gap-fill CO 2 exchange components and calculate annual totals and budgets. VPD-limitation of photosynthesis was systematically observed in grain crops of the region (occurring from 20 to 120 days during the growing season, depending on site and year), determined by the VPD regime and the numerical value of the curvature parameter of the photosynthesis-VPD-response, sigma VPD. In 78% of the 27 site-years of observations, annual gross photosynthesis in these crops significantly exceeded ecosystem respiration, resulting in a net ecosystem production of up to 2100 g CO 2 m -2 year -1. The measurement-based photosynthesis, respiration, and net ecosystem production data, as well as the estimates of the ecophysiological parameters, provide an empirical basis for parameterization and validation of mechanistic models of grain crop production in this economically and ecologically important region of North America.