• Authors:
    • Holland,R. A.
    • Eigenbrod,F.
    • Muggeridge,A.
    • Brown,G.
    • Clarke,D.
    • Taylor,G.
  • Source: Renewable and Sustainable Energy Reviews
  • Volume: 46
  • Year: 2015
  • Summary: The production of bioenergy from second generation (2G) feedstocks is being encouraged by legislation targeted at addressing a number of controversial issues including carbon emissions driven by land-use change and competition for crops used in food production. Here, we synthesise the implications of 2G feedstock production for a range of key ecosystem services beyond climate regulation. We consider feedstocks typical of temperate systems (Miscanthus; short-rotation coppice, short rotation forestry) and transitions from areas of forest, marginal land and first generation (1G) feedstock production. For transitions from 1G feedstocks, studies suggest significant benefits may arise for a number of ecosystem services, including hazard regulation, disease and pest control, water and soil quality. Although less evidence is available, the conversion of marginal land to 2G production will likely deliver benefits for some services while remaining broadly neutral for others. Conversion of forest to 2G production will likely reduce the provision of a range of services due to increased disturbance associated with shortening of the management cycle. Most importantly, further research is needed to broaden, and deepen, our understanding of the implications of transitions to 2G feedstocks on ecosystem services, providing empirical evidence for policy development, particularly for commercial deployment where landscape scale effects may emerge. A programme of research that mixes both the natural and social sciences based on an ecosystem service framework, and occurs concurrently with large scale commercial deployment of 2G feedstocks, would address this gap, providing evidence on the effectiveness of policies to promote production of 2G feedstocks on a wide range of ecosystem services. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Huffman,T.
    • Liu JianGui
    • McGovern,M.
    • McConkey,B.
    • Martin,T.
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 205
  • Year: 2015
  • Summary: Accurate estimation of greenhouse gas emissions and detailed monitoring of the carbon cycle are important for mitigation of and adaptation to climate change. On agricultural land, annual herbaceous vegetation is not considered a carbon sink, whereas perennial woody vegetation accumulates biomass over multiple years and does represent a carbon sink. This paper presents a study to estimate aboveground woody carbon stock in 1990 and its annual change from 1990 to 2000 on Canada's cropland. The cropland was stratified into zones according to soils, climate and cropping systems, within which sample plots were randomly selected and paired aerial photographs corresponding to circa 1990 and 2000 were interpreted to detect changes in perennial woody vegetation such as trees, shrubs, orchards and vineyards. Woody biomass volumes lost as a result of land use change and gained as a result of planting and growth were estimated using species composition and growth rates typical of each zone, as obtained from published literature, forest reports and charts and forestry expert knowledge. Census of agriculture data was used to scale up the sample level results to zone and national levels. Results showed that on Canada's cropland, the aboveground woody carbon stock in 1990 was 33.78.8 Tg. Between 1990 and 2000, the area covered by woody vegetation was affected negatively by removals and positively through planting and natural regeneration, leading to a net reduction in area. There was an annual increase of about 78.3 Gg over all cropland in Canada, with a net decrease in some ecozones. Although this is a comparatively small increase with a large uncertainty, it indicates that changes in woody carbon on cropland in Canada over the 1990-2000 period were relatively insignificant. Further studies may be needed to refine the carbon estimates and reduce uncertainties.
  • Authors:
    • Russell,J. R.
    • Bisinger,J. J.
  • Source: Journal of Animal Science
  • Volume: 93
  • Issue: 6
  • Year: 2015
  • Summary: Beyond grazing, managed grasslands provide ecological services that may offer economic incentives for multifunctional use. Increasing biodiversity of plant communities may maximize net primary production by optimizing utilization of available light, water, and nutrient resources; enhance production stability in response to climatic stress; reduce invasion of exotic species; increase soil OM; reduce nutrient leaching or loading in surface runoff; and provide wildlife habitat. Strategically managed grazing may increase biodiversity of cool-season pastures by creating disturbance in plant communities through herbivory, treading, nutrient cycling, and plant seed dispersal. Soil OM will increase carbon and nutrient sequestration and water-holding capacity of soils and is greater in grazed pastures than nongrazed grasslands or land used for row crop or hay production. However, results of studies evaluating the effects of different grazing management systems on soil OM are limited and inconsistent. Although roots and organic residues of pasture forages create soil macropores that reduce soil compaction, grazing has increased soil bulk density or penetration resistance regardless of stocking rates or systems. But the effects of the duration of grazing and rest periods on soil compaction need further evaluation. Because vegetative cover dissipates the energy of falling raindrops and plant stems and tillers reduce the rate of surface water flow, managing grazing to maintain adequate vegetative cover will minimize the effects of treading on water infiltration in both upland and riparian locations. Through increased diversity of the plant community with alterations of habitat structure, grazing systems can be developed that enhance habitat for wildlife and insect pollinators. Although grazing management may enhance the ecological services provided by grasslands, environmental responses are controlled by variations in climate, soil, landscape position, and plant community resulting in considerable spatial and temporal variation in the responses. Furthermore, a single grazing management system may not maximize livestock productivity and each of the potential ecological services provided by grasslands. Therefore, production and ecological goals must be integrated to identify the optimal grazing management system.
  • Authors:
    • Buckley,Cathal
    • Wall,David P.
    • Moran,Brian
    • Murphy,Paul N. C.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: This study uses a national farm survey which is part of the European Union (EU) Farm Accountancy Data Network (FADN) to develop environmental sustainability indicators in the use of nitrogen (N) and phosphorus (P) across a range of farm systems in the Republic of Ireland. Farm level micro data were used to calculate all inputs and outputs of N and P that cross the farm gate and to derive balances (kg ha(-1)) and overall use efficiencies across 827 farms in 2012. The sample is populated weighted to represents 71,480 farms nationally. Results indicated an average N balance of 71.0 kg ha(-1) and use efficiency of 36.7 % across the nationally representative sample. Nitrogen balances were between two and four times higher across specialist dairy farms compared to livestock rearing and specialist tillage systems. Nitrogen use efficiency was generally lowest across milk producing systems compared to livestock rearing and tillage systems. Phosphorus balance and use efficiency averaged 4.7 kg ha(-1) and 79.6 % respectively across the sample. Specialist tillage and dairying farms had higher average P balances compared to other livestock based systems. The approach developed in this analysis will form the benchmark for temporal analysis across these indicators for future nutrient balance and efficiency trends and could assist other members of the EU FADN to develop similar nationally representative indicators.
  • Authors:
    • Orwin,K. H.
    • Stevenson,B. A.
    • Smaill,S. J.
    • Kirschbaum,M. U. F.
    • Dickie,I. A.
    • Clothier,B. E.
    • Garrett,L. G.
    • Weerden,T. J. van der
    • Beare,M. H.
    • Curtin,D.
    • Klein,C. A. M. de
    • Dodd,M. B.
    • Gentile,R.
    • Hedley,C.
    • Mullan,B.
    • Shepherd,M.
    • Wakelin,S. A.
    • Bell,N.
    • Bowatte,S.
    • Davis,M. R.
    • Dominati,E.
    • O'Callaghan,M.
    • Parfitt,R. L.
    • Thomas,S. M.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 8
  • Year: 2015
  • Summary: Future human well-being under climate change depends on the ongoing delivery of food, fibre and wood from the land-based primary sector. The ability to deliver these provisioning services depends on soil-based ecosystem services (e.g. carbon, nutrient and water cycling and storage), yet we lack an in-depth understanding of the likely response of soil-based ecosystem services to climate change. We review the current knowledge on this topic for temperate ecosystems, focusing on mechanisms that are likely to underpin differences in climate change responses between four primary sector systems: cropping, intensive grazing, extensive grazing and plantation forestry. We then illustrate how our findings can be applied to assess service delivery under climate change in a specific region, using New Zealand as an example system. Differences in the climate change responses of carbon and nutrient-related services between systems will largely be driven by whether they are reliant on externally added or internally cycled nutrients, the extent to which plant communities could influence responses, and variation in vulnerability to erosion. The ability of soils to regulate water under climate change will mostly be driven by changes in rainfall, but can be influenced by different primary sector systems' vulnerability to soil water repellency and differences in evapotranspiration rates. These changes in regulating services resulted in different potentials for increased biomass production across systems, with intensively managed systems being the most likely to benefit from climate change. Quantitative prediction of net effects of climate change on soil ecosystem services remains a challenge, in part due to knowledge gaps, but also due to the complex interactions between different aspects of climate change. Despite this challenge, it is critical to gain the information required to make such predictions as robust as possible given the fundamental role of soils in supporting human well-being.
  • Authors:
    • Rong,Yuping
    • Ma,Lei
    • Johnson,Douglas A.
  • Source: Atmospheric Environment
  • Volume: 116
  • Year: 2015
  • Summary: Land-use types and management practices of temperate semiarid steppes may affect soil sink activity for atmospheric methane (CH4). Most previous studies related to CH4 have focused primarily on the growing season with only a few studies evaluating CH4 fluxes throughout the entire year. With CH4 exchange largely undocumented during the non-growing season, the annual CH4 uptake in different land-use types under various management practices is uncertain. The aim of this study was to investigate the annual variation of CH4 fluxes from four land-use types (ungrazed grassland, moderately grazed grassland, perennial pasture and cropland), which are the dominant land-use types in the agro-pastoral region of northern China. Fluxes of CH4 were measured throughout the year in four land-use types using a mobile greenhouse gas analyzer. Results showed that soils were a sink for atmospheric CH4 throughout the year for all land-use types. Annual CH4 uptake patterns were similar (but with quite different magnitudes) for all land-use types with low, spiky uptake during the two freeze-thaw periods, low and constant uptake during the frozen period and highly variable uptake with some emission events during the growing season. Seasonality of CH4 uptake was related to monthly mean temperature and precipitation. Monthly mean temperature and precipitation explained 56% (range: 40-83%) of the variability in monthly cumulative soil CH4 uptake. Annual CH4 uptake across all land-use types averaged 3.9 +/- 0.3 kg C ha(-1) yr(-1) (range: 1.0-10.2). CH4 uptake during the non-growing season represented about 50% (range: 41-59%) of annual CH4 uptake for the grassland types and 21% (range: 20-22%) for the cropland and perennial pasture land-use types. Moderate grazing (stocking rate 1.43 sheep ha(-1) yr(-1)) significantly increased annual CH4 uptake by 78% (P < 0.05) compared to ungrazed grassland. The highest annual CH4 uptake was observed for cropland (10.2 +/- 0.2 kg C ha(-1) yr(-1)), followed by 2.7 kg +/- 0.1C ha(-1) yr(-1) for perennial pasture. Our results documented year-long CH4 fluxes in four important land-use types in the expansive agro-pastoral region of northern China and contribute to our understanding of soil uptake levels of atmospheric CH4. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Wilson,T. M.
    • McGowen,B.
    • Mullock,J.
    • Arnall,D. B.
    • Warren,J. G.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Fertilizer-induced N 2O-N emissions (the difference between fertilized and unfertilized soils) are estimated to be 0.01 kg N 2O-N kg -1 of applied N. One approach to limiting N 2O-N production in soils is by improving nitrogen use efficiency (NUE) in dryland agricultural systems. However, baseline data on the rate of emissions is needed to determine the potential impact that these efforts might have on N 2O-N concentrations in the atmosphere. A study was established in a long-term continuous winter wheat ( Triticum aestivum L.) fertility experiment in Stillwater, OK, to determine the effects of N rate on N 2O-N emissions from a dryland winter wheat-summer fallow system in the southern Great Plains of the United States to fill this knowledge gap. Cumulative emissions of N 2O-N varied from year to year and were influenced by environment and N rate. Emissions following N fertilizer application were typically highest following N application, as well as toward the end of the summer fallow period, when summer rainfall and temperatures were conducive for N 2O-N production chambers within plots historically receiving 134 kg N ha -1 annually went unfertilized for the 2012-2013 and 2013-2014 crop years and produced N 2O-N emissions equivalent to the 45 and 90 kg N ha -1 rate treatments. Annual cumulative emissions ranged from 0.009 to 0.024 kg N 2O-N kg -1 N applied with an average of 0.015 kg N 2O-N kg -1 N applied, illustrating the variability in N 2O-N emissions.
  • Authors:
    • Reay, D. S.
    • Six, J.
    • Angst, T. E.
    • Sohi, S. P.
  • Source: Agriculture Ecosystems & Enviroment
  • Volume: 191
  • Year: 2014
  • Summary: Manure generated by dairy cattle is a useful soil amendment but contributes to greenhouse gas (GHG) emissions and water pollution from nutrient leaching. In order to assess the impact of pine chip biochar produced at a peak temperature of 550°C when added to a dairy grassland system, a one-year field study was conducted on a sandy loam soil under annual ryegrass ( Lolium multiflorum Lam.) grown for silage in Petaluma, California. Manure was applied to all plots at a rate of ca. 150 m 3 ha -1 (410 kg N ha -1). Control plots received no biochar, high application biochar plots (HB) received biochar (with a 17% ash content) at a rate of 18.8 t ha -1, and low application biochar plots (LB) received the same biochar at 5.7 t ha -1. Although the HB plots demonstrated the lowest cumulative nitrous oxide (N 2O) and methane (CH 4) emissions, there was no significant difference between treatments ( p=0.152 and p=0.496, respectively). Soil pH results from samples collected throughout the year indicated a significant treatment effect ( p=0.046), though Tukey test results indicated that there was no difference between mean values. Soil total carbon was significantly higher in HB plots at the end of the experiment ( p=0.025) and nitrate (NO 3-) intensity throughout the year (which expresses potential exposure of NO 3- to the soil microbial community) was significantly lower in HB plots compared to the control ( p=0.001). Annual cumulative potassium (K +) loss from HB plots was significantly higher than from the other treatments ( p=0.018). HB plots also demonstrated a short-term increase in phosphorus (P) and ammonium (NH 4+) in leachate during the first rainfall event following manure and biochar application ( p<0.0001 and p=0.0002, respectively) as well as a short-term decrease of NO 3- in leachate during a heavy rainfall event following a long dry spell ( p=0.036), though differences between treatments for cumulative nutrient losses were not significant ( p=0.210, p=0.061, and p=0.295, respectively for P, NH 4+, and NO 3-). These data indicate that biochar produced from pine wood chips at 550°C having high ash content (17%) is not likely to impact GHG emissions in systems with high manure application rates. Further research should be conducted in order to investigate the impact of biochar amendment on the dynamics and mobility of nutrients applied in subsequent repeated applications of dairy manure.
  • 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:
    • 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.