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Author |
Hoveid, Ø. |
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Title |
A prototype stochastic dynamic equilibrium model of the global food system |
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2015 |
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FACCE MACSUR Reports |
Abbreviated Journal |
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5 |
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Sp5-24 |
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The risks of food consumption are primarily linked to those of food production due to stochastic weather. Other sources of risk are associated with break-down of food trade or transport for weather or political reasons. Hopefully, future cures against increased risk due to climate change may be found with new agricultural technologies, systems of storage from favorable to unfavorable periods, more flexible trade-arrangements between favorable and unfavorable places. However, in the short run one has to rely on the available technology, storage facilities and trade agreements. With a realistic model of the stochastic global food system, it should be possible to measure risks of certain extreme unfavorable events.A realistic case will have countries with different climate in different growing seasons. Markets will be open for trade at a number of points per year, in which decisions of production, storage, trade and consumption can be coordinated as a static equilibrium. Determinants of this equilibrium are the weather up to this date reflected in the state of crops, the available harvested stocks and the decision-maker’s preferences. With a global stochastic process of weather, a stochastic sequence of equilibria follows. No Label |
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MACSUR Science Conference 2015 »Integrated Climate Risk Assessment in Agriculture & Food«, 8–9+10 April 2015, Reading, UK |
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no |
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MA @ admin @ |
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2139 |
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Author |
Hoveid, Ø. |
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Title |
An economist’s wish list for soil and crop modelling |
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2015 |
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FACCE MACSUR Reports |
Abbreviated Journal |
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5 |
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Sp5-25 |
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A requirement for successful integration of soil, crop and economic models is a relevant interface of the three. Economic farming models deal with choice of crops, crop management during growing season and stock management after harvest. With detailed daily weather information the state of the soil might be simulated so that a suitable sowing date can be estimated. Moreover with rational beliefs with respect to future crop prices, and with a crop model which responds to management, the management during the growing season might be optimized with respect to choice of cultivar, fertilization and irrigation. So far, as reflected by Müller and Robertson (2014), predictions of future crop yields according to crop models take only to small extent such farmer responses into account, and might therefore overestimate the responses of crop harvests to climate.Comparison of soil, crop and economic simulations with observed weather and crop outcomes might lead to estimation/calibration of unobserved parameters in all models. Such exercises need generic soil, crop and economic models which do not leave modelling outcomes to the crop modeller’s or economist’s discretion. No Label |
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MACSUR Science Conference 2015 »Integrated Climate Risk Assessment in Agriculture & Food«, 8–9+10 April 2015, Reading, UK |
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Call Number |
MA @ admin @ |
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2140 |
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Hutchings, N. |
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A comparison of farm-scale models to estimate greenhouse gas emissions from dairy farms in Europe |
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2015 |
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FACCE MACSUR Reports |
Abbreviated Journal |
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5 |
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Sp5-26 |
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Farm-scale models quantify the cycling of nitrogen (N) and carbon (C) so are powerful tools for assessing the impact of management-related decisions on greenhouse gas (GHG) emissions, especially on dairy cattle farms, where the internal cycling is particularly important. Farm models range in focus (economic, environmental) and the detail with which they represent C and N cycling. We compared four models from this range in terms of on-farm production and emissions of GHGs, using standardized scenarios. The models compared were SFarMod, DairyWise, FarmAC and HolosNor. The scenarios compared were based on two soil types (sandy clay versus heavy clay), two roughage systems (grass only versus grass and maize), and two climate types (Eindhoven versus Santander). Standard farm characteristics were; area (50 ha), milk yield (7000 kg/head/year), fertiliser (275 kg N and 150 kg N/ha/year for grass and maize, respectively). Potential yields for grass 10t dry matter (DM)/ha/year in both areas, maize 14 t DM/ha/ year in Eindhoven and 18t DM/ha/ year in Santander. The import of animal feed and the export/import manure and forages was minimized. Similar total farm direct GHG emissions for all models disguised a variation between models in the contribution of the different on-farm sources. There were large differences between models in the predictions of indirect GHG emission from nitrate leaching. Results could be explained by differences between models in the assumptions made and detail with which underlying processes were represented. We conclude that the choice of an appropriate farm model is highly dependent upon the role it should play and the context within which it will operate, so the current diversity of farm models will continue into the future. No Label |
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MACSUR Science Conference 2015 »Integrated Climate Risk Assessment in Agriculture & Food«, 8–9+10 April 2015, Reading, UK |
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MA @ admin @ |
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2141 |
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Author |
Ibañez, M. |
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Title |
Ammonia and nitrous oxide emissions from grazing cattle in Kenya |
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2015 |
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FACCE MACSUR Reports |
Abbreviated Journal |
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5 |
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Sp5-27 |
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Fertilized crops and livestock management are the main anthropogenic sources of ammonia (NH3). Ammonia emissions imply a N loss from cropping systems and have negative effects on ecosystems and human health. In Africa, it is believed that a substantial proportion of NH3 emissions results from widespread livestock management, whereas inorganic fertilizers might be of low importance. However, there is a lack of information on the mechanisms underlying the NH3 emissions derived from livestock management. Use of passive sampling approaches may enhance our knowledge on NH3 emissions by allowing systematic ecosystem investigations at a low cost; however, these techniques have not been critically evaluated for the Tropics. The main goals of our study are 1) to assess the livestock influence on the emissions of NH3 in tropical ecosystems and 2) the evaluation of experimental techniques for estimation of NH3 emissions, which could be further implemented in Africa without investment in sophisticated analytical equipment.The study was carried out in October 2014 at the farm of ILRI (Nairobi, Kenya). Ammonia fluxes from a fenced plot occupied by a herd of cows during daytime was estimated by both 1) the micrometeorological mass balance integrated horizontal flux (IHF) method and 2) the Eddy-covariance (EC) technique (using a sonic anemometer and a highly sensitive fast response NH3 trace gas monitor). Passive flux samplers (PFS) internally coated with oxalic acid were installed at different heights in 1 central and 3 background masts. PFS were exchanged every 2 days and NH3 trapped was measured colorimetrically. Soil N2O emissions were also estimated by manual chambers every 48 h along with inorganic N contents in the topsoil.Contrary to our expectations, NH3 cow’s presence did not triggered NH3 emissions. Both IHF and EC showed very low NH3 emission values along the experiment, although sensitivity varied among methods (about 100 and 30 ng NH3 m-2 s-1 as obtained by the IHF method and EC, respectively). Heavy rainfall events (˃120 mm) may be responsible for lowered NH3 volatilization. Low soil nitrate concentrations, (<0.5 mg kg-1), suggested predominant N leaching after rainfall. Soil N2O emissions were negligible, showing a maximum of only 4.5 µg N-N2O m-2 h-1 during the first day. These preliminary results represent the first dataset of NH3 emissions under controlled conditions in tropical Africa, and provide the basis for further assessments of NH3 emissions and evaluations of techniques under different ecosystems and management scenarios. No Label |
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MACSUR Science Conference 2015 »Integrated Climate Risk Assessment in Agriculture & Food«, 8–9+10 April 2015, Reading, UK |
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MA @ admin @ |
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2142 |
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Author |
Kersebaum, K.C. |
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Title |
Simulating crop rotations and management across climatic zones in Europe – an intercomparison study using fifteen models |
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Year |
2015 |
Publication |
FACCE MACSUR Reports |
Abbreviated Journal |
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Volume |
5 |
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Pages |
Sp5-28 |
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Process based crop simulation models are widely used to assess crop production under current or future climate conditions. Most studies on climate impacts on crop growth are so far focussed on single crops and single-year simulations. However, it is known that the position of crops within a rotation can influence crop growth significantly due to carry-over effects between seasons. We compared crop models on crop rotation effects from five sites across Central Europe providing in total data of 301 cropping seasons and treatments. Treatments comprised irrigation, nitrogen (N) fertilisation, atmospheric [CO2], tillage, residue management, cover crops and soils. Crop rotations were simulated with 15 crop models as single-year simulations and/or continuous simulations over whole crop rotations in “restricted calibration” runs. Lower RMSE between observed and simulated crop yields were obtained for continuous runs as compared to single-year runs. Relatively low carry-over effects were observed due to equilibration of soil water over winter and high N fertilisation levels. Consistently, a sub-set of models applied to an additional rainfed Mediterranean site reproduced larger carry-over effects of soil water. Irrigation, N supply, cover crops and atmospheric [CO2] showed clearer effects than tillage and crop residue management. Model performance varied distinctly between crops showing the necessity to provide experimental data for model calibration also for less prominent crops. No Label |
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MACSUR Science Conference 2015 »Integrated Climate Risk Assessment in Agriculture & Food«, 8–9+10 April 2015, Reading, UK |
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Notes |
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no |
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Call Number |
MA @ admin @ |
Serial |
2143 |
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