• Authors:
    • Cerri, C. C.
    • Bernoux, M.
    • Cerri, C. E. P.
    • Frazao, L. A.
    • Raucci, G. S.
    • Nunes Carvalho, J. L.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 183
  • Issue: January
  • Year: 2014
  • Summary: The objective of this study was to quantify the soil greenhouse gas (GHG) balance after the conversion of native vegetation (NV) to pasture and agricultural land and the conversion of agriculture to crop-pasture rotation (CPR) by evaluating changes in C stocks and N2O and CH4 fluxes. Soil sampling was carried out in March 2007 and April 2009 and GHG fluxes were sampled nine times between April 2007 and March 2009. The conversion of NV to pasture and agriculture decreased soil C stocks, with loss rates ranging from 0.25 to 0.64 Mg C ha(-1) yr(-1), respectively. The implementation of CPR in,agriculture areas increased soil C stocks by 0.60 Mg ha(-1) yr(-1). N2O emissions were higher in CPR and lower in NV. Emission of 1.03 kg CH4-C ha(-1) yr(-1) was observed in pasture, while in other areas consumption of CH4 was observed. The net GHG emission from the soil, including all GHG expressed in C-equivalent, indicated that the conversion of NV to pasture and agricultural land results in emissions of 0.54 and 0.72 Mg C ha(-1) yr(-1), respectively. In contrast, the adoption of CPR in areas under crop succession was a sink of 0.36 Mg ha(-1) yr(-1). Among the evaluated land use changes, only the implementation of CPR proved to be a good strategy to mitigate soil GHG emissions in Brazilian Cerrado. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Mladenoff, D. J.
    • Rothstein, D. E.
    • Forrester, J. A.
    • Palmer, M. M.
  • Source: Biomass and Bioenergy
  • Volume: 62
  • Issue: March
  • Year: 2014
  • Summary: Uncertainty exists over the magnitude of greenhouse gas (GHG) emissions associated with open land conversion to short-rotation woody biomass crops (SRWC) for bioenergy in the Northern U.S. Lake States. GHG debts incurred at the plantation establishment phase may delay the climate mitigation benefits of SRWC production. To better understand GFIG debts associated with converting open lands to SRWC, we established research plantations with willow (Salix spp), hybrid-poplar (Populus spp.), and control plots in spring 2010 at two sites in northern Michigan (ES) and Wisconsin (RH). These sites had similar climates, but differed in time since last cultivation: 5 vs. 42 years. To address the short-term effects of plantation establishment, we compared two-year biomass production and GHG emissions. We hypothesized that the long-idle ES site, with higher initial soil C and N stocks, would have higher GHG emissions following conversion compared to the recently-idle RH site, but that this would be balanced in part by greater SRWC productivity at the ES site. As hypothesized, grassland conversion resulted in two-year net GHG emissions due to land conversion of 43.21 and 33.02 Mg-CO(2)eq ha(-1) for poplar and willow at ES that was far greater than the 4.81 and 1.54 Mg-CO(2)eq ha(-1) for poplar and willow at RH. Contrary to our hypothesis, we did not observe greater SRWC productivity at ES, which will take longer than RH to reach C neutrality and begin mitigating GHG emissions. Our results show that site-specific soil and management factors determine the magnitude of GHG emissions. Published by Elsevier Ltd.
  • Authors:
    • Horwath, W. R.
    • Zhu, X.
    • You, M.
    • Han, X.
    • Miao, S.
    • Qiao, Y.
  • Source: Field Crops Research
  • Volume: 161
  • Year: 2014
  • Summary: Long-term agronomic studies are useful to determine cropping system nitrogen (N) use efficiency and the fate of applied fertilizers. We used a subtractive fertilizer experiment incorporating N, phosphorous (P), potassium (K) and swine manure to determine long-term changes in grain yield, soil organic carbon (SOC), total soil nitrogen (N), as well as carbon dioxide (CO2) and nitrous oxide (N2O) emissions. The experiment was conducted on a 22-year maize-soybean-wheat rotation in Northeastern China. Crop residues were removed for cooking fuel and forage according to local practices. Five fertilizer treatments were applied annually: control (no fertilizer), NK, NP, NPK, and NPKOM (N, P. K and manure). The NPKOM treatment increased SOC and total soil N by 4.59 and 0.45 Mg ha(-1), respectively. In contrast, SOC decreased by 10.6 and 6.64 Mg ha(-1) in the control and NK treatments, respectively. The NPKOM treatment had an average of 2.9 times more N2O emissions than the other fertilizer treatments. The cropping system balances for N and SOC, together with fuel use for farming practices and manure handling, were used to calculate the global warming potential (GWP) of the different fertilizer treatments. Due to SOC sequestration, the GWP of the NPKOM treatment (6.77 Mg C equivalent ha(-1)) was significantly lower than that of both the control (14.4 Mg C equivalent ha(-1)) and the NK treatment (12.8 Mg C equivalent ha(-1)). The results suggest that in rainfed agricultural systems in Northeastern China, the application of manure supplemented with NPK can simultaneously achieve higher grain yield and lower GWP compared to mineral fertilizers alone.
  • Authors:
    • Caesar-Tonthat, T.
    • Stevens, W. B.
    • Sainju, U. M.
    • Liebig, M. A.
    • Wang, J.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 3
  • Year: 2014
  • Summary: Little information exists about how global warming potential (GWP) is affected by management practices in agroecosystems. We evaluated the effects of irrigation, tillage, crop rotation, and N fertilization on net GWP and greenhouse gas intensity (GHGI or GWP per unit crop yield) calculated by soil respiration (GWP R and GHGI R) and organic C (SOC) (GWP C and GHGI C) methods after accounting for CO 2 emissions from all sources (irrigation, farm operations, N fertilization, and greenhouse gas [GHG] fluxes) and sinks (crop residue and SOC) in a Lihen sandy loam from 2008 to 2011 in western North Dakota. Treatments were two irrigation practices (irrigated vs. nonirrigated) and five cropping systems (conventional-till malt barley [ Hordeum vulgaris L.] with N fertilizer [CTBN], conventional-till malt barley with no N fertilizer [CTBO], no-till malt barley-pea [ Pisum sativum L.] with N fertilizer [NTB-P], no-till malt barley with N fertilizer, and no-till malt barley with no N fertilizer [NTBO]). While CO 2 equivalents were greater with irrigation, tillage, and N fertilization than without, N 2O and CH 4 fluxes were 2 to 218 kg CO 2 eq. ha -1 greater in nonirrigated NTBN and irrigated CTBN than in other treatments. Previous year's crop residue and C sequestration rate were 202 to 9316 kg CO 2 eq. ha -1 greater in irrigated NTB-P than in other treatments. Compared with other treatments, GWP R and GWP C were 160 to 9052 kg CO 2 eq. ha -1 lower in irrigated and nonirrigated NTB-P. Similarly, GHGI R and GHGI C were lower in nonirrigated NTB-P than in other treatments. Regardless of irrigation practices, NTB-P may lower net GHG emissions more than other treatments in the northern Great Plains.
  • 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:
    • Sawchik, J.
    • Franzluebbers, A. J.
    • Taboada, M. A.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 190
  • Year: 2014
  • Summary: Agriculture has become increasingly specialized in response to political, regulatory, sociological, and economic pressures to meet market demands of an ever-larger food and fiber processing sector. However, there is a growing concern with specialized agricultural systems, because of increasingly negative responses on the environment from declining soil quality to eutrophication of water bodies and enhanced greenhouse gas emissions. Literature from North and South America was reviewed that showed (i) strong positive production outcomes of crops grown following pastures, (ii) enhancement of soil organic matter with perennial pastures, particularly in the surface soil, (iii) improvement in water infiltration and water quality, and (iv) synergies between crop and livestock systems in system-wide evaluations of production and environmental quality. Therefore, agricultural soils would benefit from the re-introduction of perennial grasses and legumes into the landscape (i.e. temporally and/or spatially) by regaining soil organic matter and strengthening their capacity for long-term productivity and environmental resiliency. Published by Elsevier B.V.
  • 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:
    • Retore, M.
    • Silva, W. M.
    • Concenco, G.
    • Zanatta, J. A.
    • Tomazi, M.
    • Mercante, F. M.
    • Salton, J. C.
  • Source: Agriculture Ecosystems and Enviroment
  • Volume: 190
  • Issue: SI
  • Year: 2014
  • Summary: Performance of soil management systems was initiated in 1995 in a field experiment in Dourados, MS, Brazil, with the following systems: CS - conventional tillage; NTS - no-tillage; ICLS - integrated crop-livestock with soybean (Glycine max (L) Merr.) and pasture under no-till, rotating every two years, and PP - permanent pasture. Pastures (Brachiaria decumbens) were grazed by heifers with stocking rate adjusted to constant supply of forage. The hypothesis was that rotation of crops and pastures would be more efficient and present beneficial effects to the environment. More complex and diversified production systems may exhibit synergism between components to result in better soil physical structure, greater efficiency in use of nutrients by plants, greater accumulation of labile fractions of soil organic matter, greater diversity and biological activity in soil, and lower occurrence of nematodes and weeds. Better soil conditions in ICLS allowed greater resilience; over the years of assessment soybean and pasture yields were less affected by drought and frost. The ICLS was very efficient, accumulating soil C and reducing emissions of greenhouse gases. Soil quality was improved in integrated systems with larger number of components and greater interaction between these components (ICLS) compared to simple systems. Based on soil attributes, we affirmed in this long-term study that the ICLS system is agronomically and environmentally efficient and sustainable. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Cecagno, D.
    • Costa, S. E. V. G. de A.
    • Martins, A. P.
    • Anghinoni, I.
    • Assmann, J. M.
    • Carlos, F. S.
    • Carvalho, P. C. de F.
  • Source: Web Of Knowledge
  • Volume: 190
  • Year: 2014
  • Summary: Managing grazing stocks in integrated crop-livestock (ICL) systems under no-tillage is a key variable for reaching equilibrium in soil C and N budgets. Understanding how different plant and animal residues affect soil C and N stocks in these systems goes beyond soil dynamics since these elements are crucial for the functioning of the soil-plant-atmosphere system. The objective of this research was to determine soil C and N fractions, stocks, budgets and the carbon management index as affected by nine years of ICL with grazing intensities under no-tillage conditions. The experiment established in May 2001 in a Rhodic Hapludult (Oxisol) of southern Brazil was composed of black oat ( Avena sativa) plus ryegrass ( Lolium multiflorum) pasture in winter and soybean ( Glycine max) crop in summer. Treatments were regulated by grazing pressures to maintain forage at 10, 20, 30 and 40 cm high (G10, G20, G30 and G40, respectively). Non-grazed (NG) treatment was the control. Changes in soil C and N stocks and fractions (particulate and mineral-associated) were assessed in the ninth year of the experiment. Moderate and light grazing intensities (G20, G30 and G40) resulted in similar increases in total organic C, particulate organic C, total N, and particulate organic N compared with NG treatment. Soil C additions ranged from 0.54 to 8.68 Mg ha -1 from NG to the other grazing treatments. The G10 led to a soil N loss of 1.17 Mg ha -1 due to soil organic matter degradation. The carbon management index (CMI) values, compared with native forest (NF) as a reference, indicated soil quality loss and degradation under high grazing intensity (G10). For a positive contribution to the soil system, ICL must be managed with moderate grazing intensities and adjustment of N additions through N fixation or fertilization.
  • Authors:
    • Peel, M.
    • Western, A.
    • Wei, Y.
    • Tesemma, Z.
  • Source: Journal
  • Volume: 15
  • Issue: 4
  • Year: 2014
  • Summary: Previous studies have reported relationships between mean annual climatic variables and mean annual leaf area index (LAI), but the seasonal and spatial variability of this relationship for different vegetation cover types in different climate zones have rarely been explored in Australia. The authors developed simple models using remotely sensed LAI data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and gridded climatic data from the Australian Water Availability Project. They were able to relate seasonal and annual LAI of three different land cover types (tree, pasture, and crop) with climatic variables for the period 2000-09 in the Goulburn-Broken catchment, Australia. Strong relationships were obtained between annual LAI of crop, pasture, and tree with annual precipitation (R-2 = 0.70, 0.65, and 0.82, respectively). Monthly LAI of each land cover type also showed a strong relationship (R-2 = 0.92, 0.95, and 0.95) with the difference between precipitation P and reference crop evapotranspiration (PET; P PET) for crop, pasture, and tree. Independent model calibration and validation showed good agreement with remotely sensed MODIS LAI. The results from the application of the developed model on the future impact of climate change suggest that under all climate scenarios crop, pasture, and tree showed consistent decreases in mean annual LAI. For the future climate change scenarios considered, crop showed a decline of 7%-38%, pasture showed a decline of 5 %-24%, and tree showed a decline of 2%-11% from the historical mean annual. These results can be used to assess the impacts of future climatic and land cover changes on water resources by coupling them with hydrological models.