7 resultados para Biomass Production

em Universitätsbibliothek Kassel, Universität Kassel, Germany


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This PhD thesis focuses on current livelihoods of agro-pastoral livestock keepers, their animal nutrition, herd and rangeland management strategies. It thereby aims to contribute to sustainable rangeland management, livestock production and household income in Qinghe county of the Chinese Altay Mountain region, located in Xinjiang Uyghur Autonomous Region, PR China. In its first part the study characterizes the socio-economic situation and agricultural practices of agro-pastoralists through structured household interviews. The second part provides insights into the grazing behaviour and feed intake of small ruminants on seasonal pastures in this region, and into the quantitative and qualitative biomass offer on natural rangelands. The third part analyses the reproductive performance and annual growth of the local sheep and goat herds, and, by modelling improved feeding and culling strategies, tests herd management options that potentially improve the monetary output per female herd animal without increasing the pressure onto natural rangelands. Taken together, the results of the study suggest that, despite an increase and intensification of cropping and vegetable gardening in the region of Qinghe, livestock rearing is still the major livelihood strategy both in terms of prevalence and relative importance. However, livestock keeping is challenged by low biomass production on rangelands, due to the combined impact of high climate variability and highly localized grazing pressure on the seasonal pastures. Though government regulations try to tackle the latter aspect, their implementation is sometimes difficult. Alternatives to strict regulation of grazing periods and animal numbers on seasonal pastures are, in the case of goats, more rigorous culling strategies and, in the case of sheep and goats, strategic supplementation of the animals in the winter and spring season. However, for the latter strategy to become economically viable, an improvement of live animal and meat marketing options and an investment in local meat processing facilities that add value to the carcasses is needed. As the regional cities grow rapidly, the potential market to absorb diverse and good quality meat products is there, along with the road network connecting Qinghe county to the regional capital. Such governmental measures will not only create new job opportunities in the region but also benefit the cash income of pastoralists in this westernmost region of China.

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Pastoralism and ranching are two different rangeland-based livestock systems in dryland areas of East Africa. Both usually operate under low and irregular rainfall and consequently low overall primary biomass production of high spatial and temporal heterogeneity. Both are usually located far from town centres, market outlets and communication, medical, educational, banking, insurance and other infrastructure. Whereas pastoralists can be regarded as self-employed, gaining their livelihood from managing their individually owned livestock on communal land, ranches mostly employ herders as wage labourers to manage the livestock owned by the ranch on the ranches’ own land property. Both production systems can be similarly labour intensive and – with regard to the livestock management – require the same type of work, whether carried out as self-employed pastoralist or as employed herder on a work contract. Given this similarity, the aim of this study was to comparatively assess how pastoralists and employed herders in northern Kenya view their working conditions, and which criteria they use to assess hardship and rewards in their daily work and their working life. Their own perception is compared with the concept of Decent Work developed by the International Labour Organisation (ILO). Samburu pastoralists in Marsabit and Samburu Districts as well as herders on ranches in Laikipia District were interviewed. A qualitative analysis of 47 semi-structured interviews yielded information about daily activities, income, free time, education and social security. Five out of 22 open interviews with pastoralists and seven out of 13 open interviews with employed herders fully transcribed and subjected to qualitative content analysis to yield life stories of 12 informants. Pastoralists consider it important to have healthy and satisfied animals. The ability to provide food for their family especially for the children has a high priority. Hardships for the pastoralists are, if activities are exhausting, and challenging, and dangerous. For employed herders, decent conditions are if their wages are high enough to be able to provide food for their family and formal education for their children. It is further most important for them to do work they are experienced and skilled in. Most employed herders were former pastoralists, who had lost their animals due to drought or raids. There are parallels between the ILO ‘Decent Work’ concept and the perception of working conditions of pastoralists and employed herders. These are, for example, that remuneration is of importance and the appreciation by either the employer or the community is desired. Some aspects that are seen as important by the ILO such as safety at work and healthy working conditions only play a secondary role to the pastoralists, who see risky and dangerous tasks as inherent characteristics of their efforts to gain a livelihood in their living environment.

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Inadequate quantity and quality of livestock feed is a persistent constraint to productivity for mixed crop-livestock farming in eastern Democratic Republic of Congo. To assess on-farm niches of improved forages, demonstration trials and participatory on-farm research were conducted in four different sites. Forage legumes included Canavalia brasiliensis (CIAT 17009), Stylosanthes guianensis (CIAT 11995) and Desmodium uncinatum (cv. Silverleaf), while grasses were Guatemala grass (Tripsacum andersonii), Napier grass (Pennisetum purpureum) French Cameroon, and a local Napier line. Within the first six months, forage legumes adapted differently to the four sites with little differences among varieties, while forage grasses displayed higher variability in biomass production among varieties than among sites. Farmers’ ranking largely corresponded to herbage yield from the first cut, preferring Canavalia, Silverleaf desmodium and Napier French Cameroon. Choice of forages and integration into farming systems depended on land availability, soil erosion prevalence and livestock husbandry system. In erosion prone sites, 55–60% of farmers planted grasses on field edges and 16–30% as hedgerows for erosion control. 43% of farmers grew forages as intercrop with food crops such as maize and cassava, pointing to land scarcity. Only in the site with lower land pressure, 71% of farmers grew legumes as pure stand. When land tenure was not secured and livestock freely roaming, 75% of farmers preferred to grow annual forage legumes instead of perennial grasses. Future research should develop robust decision support for spatial and temporal integration of forage technologies into diverse smallholder cropping systems and agro-ecologies.

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Energy policies around the world are mandating for a progressive increase in renewable energy production. Extensive grassland areas with low productivity and land use limitations have become target areas for sustainable energy production to avoid competition with food production on the limited available arable land resources and minimize further conversion of grassland into intensively managed energy cropping systems or abandonment. However, the high spatio-temporal variability in botanical composition and biochemical parameters is detrimental to reliable assessment of biomass yield and quality regarding anaerobic digestion. In an approach to assess the performance for predicting biomass using a multi-sensor combination including NIRS, ultra-sonic distance measurements and LAI-2000, biweekly sensor measurements were taken on a pure stand of reed canary grass (Phalaris aruninacea), a legume grass mixture and a diversity mixture with thirty-six species in an experimental extensive two cut management system. Different combinations of the sensor response values were used in multiple regression analysis to improve biomass predictions compared to exclusive sensors. Wavelength bands for sensor specific NDVI-type vegetation indices were selected from the hyperspectral data and evaluated for the biomass prediction as exclusive indices and in combination with LAI and ultra-sonic distance measurements. Ultrasonic sward height was the best to predict biomass in single sensor approaches (R² 0.73 – 0.76). The addition of LAI-2000 improved the prediction performance by up to 30% while NIRS barely improved the prediction performance. In an approach to evaluate broad based prediction of biochemical parameters relevant for anaerobic digestion using hyperspectral NIRS, spectroscopic measurements were taken on biomass from the Jena-Experiment plots in 2008 and 2009. Measurements were conducted on different conditions of the biomass including standing sward, hay and silage and different spectroscopic devices to simulate different preparation and measurement conditions along the process chain for biogas production. Best prediction results were acquired for all constituents at laboratory measurement conditions with dried and ground samples on a bench-top NIRS system (RPD > 3) with a coefficient of determination R2 < 0.9. The same biomass was further used in batch fermentation to analyse the impact of species richness and functional group composition on methane yields using whole crop digestion and pressfluid derived by the Integrated generation of solid Fuel and Biogas from Biomass (IFBB) procedure. Although species richness and functional group composition were largely insignificant, the presence of grasses and legumes in the mixtures were most determining factors influencing methane yields in whole crop digestion. High lignocellulose content and a high C/N ratio in grasses may have reduced the digestibility in the first cut material, excess nitrogen may have inhibited methane production in second cut legumes, while batch experiments proved superior specific methane yields of IFBB press fluids and showed that detrimental effects of the parent material were reduced by the technical treatment

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In Khartoum (Sudan) a particular factor shaping urban land use is the rapid expansion of red brick making (BM) for the construction of houses which occurs on the most fertile agricultural Gerif soils along the Nile banks. The objectives of this study were to assess the profitability of BM, to explore the income distribution among farmers and kiln owners, to measure the dry matter (DM), nitrogen (N), phosphorus (P), potassium (K) and organic carbon (C_org) in cow dung used for BM, and to estimate the greenhouse gas (GHG) emissions from burned biomass fuel (cow dung and fuel wood). About 49 kiln owners were interviewed in 2009 using a semi-structured questionnaire that allowed to record socio-economic and variable cost data for budget calculations, and determination of Gini coefficients. Samples of cow dung were collected directly from the kilns and analyzed for their nutrients concentrations. To estimate GHG emissions a modified approach of the Intergovernmental Panel on Climate Change (IPCC) was used. The land rental value from red brick kilns was estimated at 5-fold the rental value from agriculture and the land rent to total cost ratio was 29% for urban farms compared to 6% for BM. The Gini coefficients indicated that income distribution among kiln owners was more equal than among urban farmers. Using IPCC default values the 475, 381, and 36 t DM of loose dung, compacted dung, and fuel wood used for BM emit annually 688, 548, and 60 t of GHGs, respectively.

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Extensive grassland biomass for bioenergy production has long been subject of scientific research. The possibility of combining nature conservation goals with a profitable management while reducing competition with food production has created a strong interest in this topic. However, the botanical composition will play a key role for solid fuel quality of grassland biomass and will have effects on the combustion process by potentially causing corrosion, emission and slagging. On the other hand, botanical composition will affect anaerobic digestibility and thereby the biogas potential. In this thesis aboveground biomass from the Jena-Experiment plots was harvested in 2008 and 2009 and analysed for the most relevant chemical constituents effecting fuel quality and anaerobic digestibility. Regarding combustion, the following parameters were of main focus: higher heating value (HHV), gross energy yield (GE), ash content, ash softening temperature (AST), K, Ca, Mg, N, Cl and S content. For biogas production the following parameters were investigated: substrate specific methane yield (CH4 sub), area specific methane yield (CH4 area), crude fibre (CF), crude protein (CP), crude lipid (CL) and nitrogen-free extract (NfE). Furthermore, an improvement of the fuel quality was investigated through applying the Integrated generation of solid Fuel and Biogas from Biomass (IFBB) procedure. Through the specific setup of the Jena-Experiment it was possible to outline the changes of these parameters along two diversity gradients: (i) species richness (SR; 1 to 60 species) and (ii) functional group (grasses, legumes, small herbs and tall herbs) presence. This was a novel approach on investigating the bioenergy characteristic of extensive grassland biomass and gave detailed insight in the sward-composition¬ - bioenergy relations such as: (i) the most relevant SR effect was the increase of energy yield for both combustion (annual GE increased by 26% from SR8→16 and by 65% from SR8→60) and anaerobic digestion (annual CH4 area increased by 22% from SR8→16 and by 49% from SR8→60) through a strong interaction of SR with biomass yield; (ii) legumes play a key role for the utilization of grassland biomass for energy production as they increase the energy content of the substrate (HHV and CH4 sub) and the energy yield (GE and CH4 area); (iii) combustion is the conversion technique that will yield the highest energy output but requires an improvement of the solid fuel quality in order to reduce the risk of corrosion, emission and slagging related problems. This was achieved through applying the IFBB-procedure, with reductions in ash (by 23%), N (28%), K (85%), Cl (56%) and S (59%) and equal levels of concentrations along the SR gradient.

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Rising global energy needs and limited fossil fuel reserves have led to increased use of renewable energies. In Germany, this has entailed massive exploitation of agricultural biomass for biogas generation, associated with unsustainable farming practices. Organic agriculture not only reduces negative environmental impacts, organic farmers were also prime movers in anaerobic digestion (AD) in Germany. This study’s aim was to identify the structure, development, and characteristics of biogas production associated with organic farming systems in order to estimate further development, as well as energetic and associated agronomic potentials. Surveys were conducted among organic farms with AD technology. 144 biogas plants could be included in the analysis. Total installed electrical capacity was 30.8 MWel, accounting for only 0.8% of the total installed electrical capacity in the German biogas sector. Recently, larger plant types (>250 kWel) with increased use of (also purchased) energy crops have emerged. Farmers noticed increases in yields (22% on average) and quality of cash crops in arable farming through integrated biogas production. In conclusion, although the share of AD in organic farming is relatively small it can provide various complementary socio-ecological benefits such as the enhancement of food output through digestate fertilization without additional need for land, while simultaneously reducing greenhouse gas emissions from livestock manures and soils. However, to achieve this eco-functional intensification, AD systems and their management have to be well adapted to farm size and production focus and based primarily on residue biomass.