• Authors:
    • Zhu, H. T.
    • Fang, X. X.
    • Pelton, M. P.
    • Blanco-Canqui, H.
    • Goddard, S.
    • Milner, M.
    • Yang, H. S.
    • Liska, A. J.
    • Suyker, A. E.
  • Source: Nature Climate Change
  • Volume: 4
  • Issue: 5
  • Year: 2014
  • Summary: Removal of corn residue for biofuels can decrease soil organic carbon (SOC; refs 1, 2) and increase CO 2 emissions because residue C in biofuels is oxidized to CO 2 at a faster rate than when added to soil. Net CO 2 emissions from residue removal are not adequately characterized in biofuel life cycle assessment (LCA; refs 6, 7, 8). Here we used a model to estimate CO 2 emissions from corn residue removal across the US Corn Belt at 580 million geospatial cells. To test the SOC model, we compared estimated daily CO 2 emissions from corn residue and soil with CO 2 emissions measured using eddy covariance, with 12% average error over nine years. The model estimated residue removal of 6 Mg per ha -1 yr -1 over five to ten years could decrease regional net SOC by an average of 0.47-0.66 Mg C ha -1 yr -1. These emissions add an average of 50-70 g CO 2 per megajoule of biofuel (range 30-90) and are insensitive to the fraction of residue removed. Unless lost C is replaced, life cycle emissions will probably exceed the US legislative mandate of 60% reduction in greenhouse gas (GHG) emissions compared with gasoline.
  • Authors:
    • Aiyelari, E. A.
    • Oku, E. E.
  • Source: Journal of Agriculture and Environment for International Development
  • Volume: 108
  • Issue: 1
  • Year: 2014
  • Summary: Use of vetiver as a green technology can address African farmers' ecological problems through protecting farmlands on steep lands. In addition, it offers the opportunity to integrate smallholders into the green economy as it sequesters carbon, keep water and nutrient fluxes within the system, sustain high crop yield with climate change adaptation potentials. This is particularly important as more slopes are converted to agricultural lands due to increase in population density and poverty. Thus, the study investigated the optimal strip width for increases in soil productivity and farmers' preferences for space. The study planted maize and cassava in between vetiver field structures (VFS) installed on the contour at 5, 15, 25 m apart and compared it with Farmers' Practice (FP) on a 45% slope and quantified the amount of soil displaced, water and plant nutrient losses and crop yields. Vetiver installed at 5 m surface interval spacing significantly enhanced carbon sequestration indicating potentials for GHGs mitigation and reduced N, P, Ca, Mg, Na and K losses when compared with FP. Vetiver allowed only 7% rainfall lost as against 29% on FP this demonstrates the climate change adaptation potentials of vetiver. Soil displaced under FP was 68 times higher than the soil loss tolerance limit of 12 t ha -1 yr -1 whereas under VFS at 5, 15 and 25 m it was 21/2, 13 and 12 times higher. Maize grain yield were 35, 23 and 24% higher on the VFS field at 5, 15 and 25 m respectively when compared to FP. The corresponding values for cassava fresh tuber were 43, 32 and 29% higher. Unlike other technologies, vetiver grass contributes to the livelihood of the farmers by providing raw material for house thatching, handicrafts and fodder for livestock during lean seasons.
  • Authors:
    • Kludze, H.
    • McDonald,I.
    • Dadfar, H.
    • MacLean, H. L.
    • Dias, G.
    • Deen, B.
    • Sanscartier, D.
  • Source: GCB Bioenergy
  • Volume: 6
  • Issue: 4
  • Year: 2014
  • Summary: Replacement of fossil fuels with sustainably produced biomass crops for energy purposes has the potential to make progress in addressing climate change concerns, nonrenewable resource use, and energy security. The perennial grass Miscanthus is a dedicated energy crop candidate being field tested in Ontario, Canada, and elsewhere. Miscanthus could potentially be grown in areas of the province that differ substantially in terms of agricultural land class, environmental factors and current land use. These differences could significantly affect Miscanthus yields, input requirements, production practices, and the types of crops being displaced by Miscanthus establishment. This study assesses implications on life cycle greenhouse gas (GHG) emissions of these differences through evaluating five Miscanthus production scenarios within the Ontario context. Emissions associated with electricity generation with Miscanthus pellets in a hypothetically retrofitted coal generating station are examined. Indirect land use change impacts are not quantified but are discussed. The net life cycle emissions for Miscanthus production varied greatly among scenarios (-90-170 kg CO(2)eq per oven dry tonne of Miscanthus bales at the farm gate). In some cases, the carbon stock dynamics of the agricultural system offset the combined emissions of all other life cycle stages (i.e., production, harvest, transport, and processing of biomass). Yield and soil C of the displaced agricultural systems are key parameters affecting emissions. The systems with the highest potential to provide reductions in GHG emissions are those with high yields, or systems established on land with low soil carbon. All scenarios have substantially lower life cycle emissions (-20-190 g CO(2)eq kWh(-1)) compared with coal-generated electricity (1130 g CO(2)eq kWh(-1)). Policy development should consider the implication of land class, environmental factors, and current land use on Miscanthus production.
  • Authors:
    • Sui, P.
    • Chen, Y.
    • Zhang, M.
    • Gao, W.
    • Yang, X.
  • Source: Journal of Cleaner Production
  • Volume: 76
  • Issue: August
  • Year: 2014
  • Summary: Increasing atmospheric concentrations of greenhouse gases has caused grievous global warming and associated consequences. Lowering carbon footprint to promote the development of cleaner production demands the immediate attention. In this study, the carbon footprint calculations were performed on five cropping systems in North China Plain from 2003 to 2010. The five cropping systems included sweet potato -> cotton -> sweet potato -> winter wheat-summer maize (SpCSpWS, 4-year cycle), ryegrass-cotton -> peanut -> winter wheat-summer maize (RCPWS, 3-year cycle), peanut -> winter wheat-summer maize (PWS, 2-year cycle), winter wheat-summer maize (WS, 1-year cycle), and continuous cotton (Cont C), established in a randomized complete-block design with three replicates. We used a modified carbon footprint calculation with localized greenhouse gas emissions parameters to analyze the carbon footprint of each cropping system per unit area, per kg biomass, and per unit economic output. Results showed that the lowest annual carbon footprint values were observed in SpCSpWS among the five cropping systems, which were only 27.9%, 28.2% and 25.0% of those in WS rotation system (the highest carbon footprint) in terms of per unit area, per unit biomass, and per unit economic output, respectively. The five cropping systems showed the order of SpCSpWS < Cont C < RCPWS < PWS < WS sorting by their annual carbon footprint calculated by all the three metrics above-mentioned. Results revealed that appropriate diversified crop rotation systems could contribute to decreased carbon footprint compared with conventional intensive crop production system in North China Plain. (C) 2014 Elsevier Ltd. All rights reserved.
  • Authors:
    • Zheng, J. F.
    • Pan, G. X.
    • Li, L. Q.
    • Zhang, X. H.
    • Zhang, A F.
    • Liu, Y. M.
    • Kibue, G. W.
    • Ye, Y. X.
    • Liu, X. Y.
    • Zheng, J. W.
  • Source: Agricultural Systems
  • Volume: 129
  • Year: 2014
  • Summary: Biochar's effects on improving soil fertility, enhancing crop productivity and reducing greenhouse gases (GHGs) emission from croplands had been well addressed in numerous short-term experiments with biochar soil amendment (BSA) mostly in a single crop season/cropping year. However, the persistence of these effects, after a single biochar application, has not yet been well known due to limited long-term field studies so far. Large scale BSA in agriculture is often commented on the high cost due to large amount of biochar in a single application. Here, we try to show the persistence of biochar effects on soil fertility and crop productivity improvement as well as GHGs emission reduction, using data from a field experiment with BSA for 5-crop seasons in central North China. A single amendment of biochar was performed at rates of 0 (C0), 20 (C20) and 40 t ha -1 (C40) before sowing of the first crop season. Emissions of CO 2, CH 4 and N 2O were monitored with static closed chamber method throughout the crop growing season for the 1st, 2nd and 5th cropping. Crop yield was measured and topsoil samples were collected at harvest of each crop season. BSA altered most of the soil physico-chemical properties with a significant increase over control in soil organic carbon (SOC) and available potassium (K) content. The increase in SOC and available K was consistent over the 5-crop seasons after BSA. Despite a significant yield increase in the first maize season, enhancement of crop yield was not consistent over crop seasons without corresponding to the changes in soil nutrient availability. BSA did not change seasonal total CO 2 efflux but greatly reduced N 2O emissions throughout the five seasons. This supported a stable nature of biochar carbon in soil, which played a consistent role in reducing N 2O emission, which showed inter-annual variation with changes in temperature and soil moisture conditions. The biochar effect was much more consistent under C40 than under C20 and with GHGs emission than with soil property and crop yield. Thus, our study suggested that biochar amended in dry land could sustain a low carbon production both of maize and wheat in terms of its efficient carbon sequestration, lower GHGs emission intensity and soil improvement over 5-crop seasons after a single amendment.
  • Authors:
    • Horwath, W. R.
    • Hijmans, R. J.
    • Perlman, J.
  • Source: Global Ecology and Biogiography
  • Volume: 23
  • Issue: 8
  • Year: 2014
  • Summary: Aim: Modelling complex environmental and ecological processes over large geographic areas is challenging, particularly when basic research and model development for such processes has historically been at the local scale. Moving from local toward global analysis brings up numerous issues related to data processing, aggregation, tradeoffs between model quality and data quality, and prioritization of data collection and/or compilation efforts. We studied these issues in the context of modelling emissions of N 2O (a potent greenhouse gas) from agricultural soils. Location: Global. Methods: We developed metamodels of the DeNitrification-DeComposition (DNDC) model, a mechanistic model that simulates greenhouse gas emissions from agricultural soils, to estimate global N 2O emissions from maize and wheat fields. We ran DNDC for a diverse sample of global climate and soil types, and fitted the model output as a function of (sometimes simplified) model input variables, using the random forest machine learning algorithm. We used the metamodels to estimate global N 2O emissions from maize and wheat at a very high spatial resolution ( c. 1 km 2) and examined the effects of different approaches of using soil data as well as the effects of spatial aggregation of soil and climate data. Results: The average coefficient of determination ( R2) between holdout data (DNDC output not used to construct the metamodel) and metamodel predictions was 0.97 for maize and 0.91 for wheat. The metamodels were sensitive to soil properties, particularly to soil organic carbon content. Global emission estimates with the metamodel were highly sensitive to the spatial aggregation and other forms of generalization of soil data, but much less so to aggregation of climate data. Main conclusions: Using a simplified metamodel with data of high spatial resolution could produce results that are more accurate than those obtained with a full mechanistic model and lower-resolution data.
  • Authors:
    • Barth, G.
    • Pauletti, V.
    • Tomazi, M.
    • de Moraes, A.
    • Zanatta, J. A.
    • Bayer, C.
    • Dieckow, J.
    • Piva, J. T.
    • Piccolo, M. de C.
  • Source: Agriculture Ecosystems and Evviroment
  • Volume: 190
  • Issue: SI
  • Year: 2014
  • Summary: We assessed the impact of integrated crop-livestock (CL), with silage maize (Zea mays L.) in summer and grazed annual-ryegrass (Lolium multiflorum Lam.) in winter, and continuous crop (CC), with annualryegrass used only as cover-crop, on net greenhouse gas emission from soil (NetGHG-S) in a subtropical Ferralsol of a 3.5-year-old experiment in Brazil. Emissions from animal excreta in CL were estimated. Soil N2O fluxes after N application to maize were higher in CL (max. 181 mu g N2O-N m(-2) h(-1)) than in CC (max. 132 mu g N2O-N m(-2) h(-1)). The cumulative annual N2O emission from soil in CL surpassed that in CC by more than three-times (4.26 vs. 1.26 kg N2O-N ha(-1), p < 0.01), possibly because of supplementary N application to grazed ryegrass in CL (N was not applied in cover-crop ryegrass of CC) and a certain degree of soil compaction visually observed in the first few centimetres after grazing. The estimated annual N2O emission from excreta in CL was 2.35 kg N2O-N ha(-1). Cumulative annual CH4 emission was not affected significantly (1.65 in CL vs. 1.08 kg CH4-C ha(-1) in CC, p = 0.27). Soil organic carbon (OC) stocks were not affected by soil use systems, neither in 0-20-cm (67.88 in CL vs. 67.20 Mg ha(-1) in CC, p = 0.62) or 0-100-cm (234.74 in CL vs. 234.61 Mg ha(-1) in CC, p = 0.97). The NetGHG-S was 0.652 Mg CO2-C-eq ha(-1) year(-1) higher in CL than in CC. Crop-livestock emitted more N2O than CC and no soil OC sequestration occurred to offset that emission. Management of fertiliser- and excreta-N must be focused as a strategy to mitigate N2O fluxes in CL. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Sakalauskas, A.
    • Avizienyte, D.
    • Romaneckas, K.
    • Masilionyte, L.
    • Buragiene, S.
    • Sarauskis, E.
  • Source: Energy
  • Volume: 69
  • Issue: SI
  • Year: 2014
  • Summary: To achieve energy independence, Lithuania and other Baltic countries are searching for new ways to produce energy. Maize is a crop that is suitable for both food and forage, as well as for the production of bioenergy. The objective of this work was to assess the energy efficiency of maize cultivation technologies in different systems of reduced tillage. The experimental research and energy assessment was carried out for five different tillage systems: DP (deep ploughing), SP (), DC (deep cultivation), SC (shallow cultivation) and NT (no tillage). The assessment of the fuel inputs for these systems revealed that the greatest amount of diesel fuel (67.2 l ha -1) was used in the traditional DP system. The reduced tillage systems required 12-58% less fuel. Lower fuel consumption reduces the costs of technological operations and reduces CO 2 emissions, which are associated with the greenhouse effect. The agricultural machinery used in reduced tillage technologies emits 107-223 kg ha -1 of CO 2 gas into the environment, whereas DP emits 253 kg ha -1 of CO 2. The energy analysis conducted in this study showed that the greatest total energy input (approximately 18.1 GJ ha -1) was associated with the conventional deep-ploughing tillage technology. The energy inputs associated with the reduced-tillage technologies, namely SP, DC and SC, ranged from 17.1 to 17.6 GJ ha -1. The lowest energy input (16.2 GJ ha -1) was associated with the NT technology. Energy efficiency ratios for the various technologies were calculated as a function of the yield of maize grain and biomass. The best energy balance and the highest energy efficiency ratio (14.0) in maize cultivation was achieved with the NT technology. The energy efficiency ratios for DP, SP, DC and SC were 12.4, 13.4, 11.3 and 12.0, respectively.
  • Authors:
    • Singh, B.
    • Smider, B.
  • Source: Agriculture Ecosystems and Enviroment
  • Volume: 191
  • Issue: SI
  • Year: 2014
  • Summary: Intensive greenhouse industry wastes large amounts of nutrient-rich green waste through improper disposal practices. Converting this greenhouse waste into biochar for soil application offers a viable option to recycle nutrients and long-term C storage. This study was carried out to evaluate the agronomic potential of a biochar produced from tomato green waste in two contrasting soils. We also estimated the amount of waste generated from intensive greenhouse tomato production in Australia. From weekly measurements of leaf picking over a 13-week period, we estimate approximately 133 Mg ha -1 year -1 of green waste on fresh weight basis. Biochar, produced by slowly pyrolysing the green waste at 550°C, had very high-pH (12.1), electrical conductivity (EC, 54.2 dS m -1), ash content (560 g kg -1) and CaCO 3 equivalence (330 g kg -1). Agronomic performance of the biochar was evaluated by growing Hybrid sweet corn ( Zea mays var. rugosa cv - Sentinel) in the greenhouse for 7 weeks. We used three levels of biochar (0, 5 and 15 g kg -1 soil) in a factorial combination with three fertiliser rates (0, 50 and 100% of the recommended rate) applied to two contrasting soils (an Orthic Tenosol and a Red Ferrosol). Biochar application to the Ferrosol significantly increased the shoot dry matter of corn and contrastingly decreased the yield in case of the Tenosol. The positive effect of the biochar in the Ferrosol was attributed to release of nutrients from the biochar and biochar's liming effect and associated increased availability of nutrients. However, in poorly buffered Tenosol the application of biochar produced phytotoxic effects due to excessive soluble salts and high pH. The uptake of most nutrient elements increased in the corn shoot in the Ferrosol and decreased in the Tenosol. Although the biochar produced from green waste was highly alkaline and contained excessive soluble salts, given the right soil properties it can be a good soil ameliorant. The true agronomic potential of the biochar should be further evaluated in different soil types under field conditions.
  • Authors:
    • Sanginga, P.
    • Amede, T.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION Pages:
  • Volume: 69
  • Issue: 4
  • Year: 2014