Suchergebnisse

Not Available ; Worldwide, more than 80 percent of the cropped area depends on rainfall alone. Rainfed agriculture is practiced in almost all hydroclimatic zones, and can be highly productive. However, in many dry subhumid regions, tropical semiarid and arid regions, as well as in some temperate regions yields tend to be relatively low. With highly variable rainfall, long dry seasons, recurrent droughts and dry spells as well as floods, water tends to be a key constraint for agricultural production systems in these regions. Especially in Sub-Saharan Africa, where 96 percent of the cropland is rainfed, erratic and sparse rainfall often combines with arid conditions, high temperatures, and shallow soils with poor nutrient status to provide extremely uncertain conditions for agriculture. Farmers, and especially the poor, are intrinsically risk-averse, and in these conditions they tend to adopt low-input strategies with limited yield potential even in good rainfall years. The need to improve water management in water-constrained rainfed areas is often emphasized. In particular by increasing timely water availability and the water uptake of crops, yields can be significantly enhanced and agricultural productivity improved. Research has shown that better water management, coupled with improved soil and crop management, can more than double agricultural productivity in rainfed areas with currently low yields. With climate change and increasing food prices, even more emphasis needs to be placed on addressing water management in rainfed agriculture as a key determinant for agricultural production and productivity. However, governments and donors have tended to pay relatively little attention to this area, and investments remain low. During the last decade, for example, commitments to improving water management in rainfed agriculture in World Bank-supported projects amounted to less than 15 percent of the commitments to the irrigation and drainage subsector. Improvements in agricultural water management can be categorized into four broad approaches (one physical and three non-physical), with each comprising a variety of measures. The most usual approach comprises soil and water management techniques, including structural measures (such as stone barriers, bunds or terraces) and in-field or agronomic practices (such as mulching, fertilizing, intercropping, crop rotation, agroforestry and reduced tillage). ; Not Available

AbstractThis study presents a greenhouse gas (GHG) life cycle assessment of 1 tonne of wheat transported to port in south‐western Australia, including emissions from prefarm, onfarm and postfarm stages. The prefarm stage included GHG emissions from agricultural machinery, fertiliser and pesticide production. The onfarm stage included GHG emissions from diesel use, liming and nitrous oxide (N2O) emissions from N fertiliser applications. The postfarm stage included grain storage and transportation to the port. GHG emissions decreased from 487 to 304 kg carbon dioxide (CO2) equivalents when we used regional‐specific data for N2O emissions instead of the IPCC default value for the application of synthetic N fertilisers to land (1.0%). Fertiliser production in the prefarm stage contributed significantly (35%) to GHG, followed by onfarm CO2 emissions (27%) and emissions from transportation of inputs and wheat (12%). N2O emissions from paddock represented 9% of the total GHGs emitted. We recommend utilising regionally specific data for soil N2O emissions, rather than international default values, when assessing GHG for agricultural production systems.

AbstractDue to the large amount of greenhouse gas (GHG) emissions and the high dependence on fossil energy, the aviation industry has attracted a lot of attention for emission reduction and sustainable development. Biomass is a green and sustainable renewable resource, and its chemical conversion to produce bio-jet fuel is considered to be an effective way to replace fossil jet fuel and achieve emission reduction. In this study, the cradle-to-grave life cycle analysis is conducted for three bio-jet fuel conversion pathways, including biomass aqueous phase reforming (APR), hydrogenated esters and fatty acids (HEFA), and hydrothermal liquefaction (HTL). Compared with fossil jet fuels, the three bio-jet fuels have a great advantage on global warming potential (GWP), contributing 29.2, 43.6 and 51.2 g CO2-eq/MJ respectively. In general, as a relatively new bio-jet fuel conversion technology, the technology of aqueous phase reforming has minimal environmental impact. If the barriers of raw material availability and economy could be broken down, bio-jet fuel will have great development potential in replacing fossil jet fuel and realizing sustainable development.

Greenhouse gas (GHG) emissions from agriculture comprise 10-12% of anthropocentric global emissions; and 76% of the agricultural emissions are generated in the developing world. Landscape GHG accounting is an effective way to efficiently develop baseline emissions and appropriate mitigation approaches. In a 9,736-hectare case study area dominated by rice and wheat in the Karnal district of Haryana state, India, the authors used a low-cost landscape agricultural GHG accounting method with limited fieldwork, remote sensing, and biogeochemical modeling. We used the DeNitrification-DeComposition (DNDC) model software to simulate crop growth and carbon and nitrogen cycling to estimate net GHG emissions, with information based on the mapping of cropping patterns over time using multi- resolution and multi-temporal optical remote sensing imagery. We estimated a mean net emission of 78,620 tCO2e/yr (tons of carbon dioxide equivalents per year) with a 95% confidence interval of 51,212-106,028 tCO2e/yr based on uncertainties in our crop mapping and soil data. A modeling sensitivity analysis showed soil clay fraction, soil organic carbon fraction, soil density, and nitrogen amendments to be among the most sensitive factors, and therefore critical to capture in field surveys. We recommend a multi-phase approach to increase efficiency and reduce cost in GHG accounting. Field campaigns and aspects of remote sensing image characteristics can be optimized for targeted landscapes through solid background research. An appropriate modeling approach can be selected based on crop and soil characteristics. Soil data in developing world landscapes remain a significant source of uncertainty for studies like these and should remain a key research and data development effort. ; European Union ; International Fund for Agricultural Development

Part 19: Advances in Cleaner Production ; International audience ; The human addiction to fossil fuel and global warming leads to the search for alternative energy sources. The Brazilian government intends to increase its dependence on renewable energy sources, including hydropower, biomass, and wind. Many political and economic efforts have been directed to wind-energy, however, there is a lack of case-specific information regarding its performance for CO2 emissions and dependence on fossil fuels. The aim of this work is to assess the global warming potential (GWP) and the fossil energy embodied in an important wind-energy complex located at Piauí State, Brazil. Results show that evaluated wind-complex demands lower amount of fossil energy (0.0404 MJ) and has lower GWP (4.13 gCO2-eq.) per kWh of electricity generated when compared to landmark studies. Wind-electricity showed better performance than hydroelectricity (0.1516 MJ/kWh and 11.84 gCO2-eq./kWh), which supports wind-electricity as an important alternative towards an economy decarbonization.

Greenhouses require large amounts of energy, which is the dominant factor making greenhouses more emission intensive than open-field cultivation. Alternative heating systems, such as combined heat and power (CHP), biogas, and industrial waste heat, are continuously being researched for reducing the environmental impacts of greenhouses. This paper assesses utilizing industrial waste heat and CO2 enrichment in greenhouses as an example to propose "agro-industrial symbiosis" (AIS), to refer to a symbiotic co-operation between agricultural and industrial partners. The global warming potentials (GWPs) of greenhouse production using different heating systems are inadequately compared in the literature, which is the research gap addressed herein. Additionally, potential emission reductions of greenhouse production with industrial waste heat are yet to be assessed via lifecycle assessment (LCA). A comparative LCA of Finnish greenhouse tomato and cucumber production using various heating systems was conducted. Naturally, replacing fossil fuels with bioenergy and renewables significantly decreases the GWP. CHP systems result in decreased GWP only when using biogas as the energy source. Additionally, utilizing industrial waste heat and CO2 resulted in a low GWP. These results are applicable worldwide to guide political decision-making and clean energy production in the horticultural sector.