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- Gärdenäs, Annemieki, et al.
(författare)
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Estimating soil carbon stock changes by process-based models and soil inventories : uncertainties and complementarities
- 2011
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Ingår i: Soil Carbon in Sensitive European Ecosystems. - Oxford : Wiley-Blackwell. - 9781119970019
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Bokkapitel (refereegranskat)abstract
- In this chapter, four examples of scientific questions and challenges in which process-oriented modelling could provide a useful contribution for accounting soil organic carbon (SOC) stocks and changes are presented. These challenges include cases i) when measurements are either time-consuming and/or expensive or there are methodological limitations; ii) an attempt to verify the national soil inventory estimates through comparison with process-based model estimates; iii) prediction of the potential impact on SOC changes due to land-use change; and iv) a comparison of different scenarios for mitigating GHG-emissions. We found that the use of process-based models offers a complementary way to account SOC change and provides an option for assessing the potential impact of climate and land-use change on SOC stocks. However, uncertainty in model estimates is inherent and needs to be communicated. Progress has been made in the assessment of uncertainty and there is growing awareness of how this uncertainty can be communicated. Suggestions for collaborative approaches are presented in order to reduce the uncertainties.
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| 3. |
- Chala, Workneh Bedada, et al.
(författare)
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Long-term addition of compost and NP fertilizer increases crop yield and improves soil quality in experiments on smallholder farms
- 2014
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Ingår i: Agriculture, Ecosystems and Environment. - : Elsevier BV. - 0167-8809 .- 1873-2305. ; 195, s. 193-201
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Tidskriftsartikel (refereegranskat)abstract
- Soil fertility decline due to low nutrient input is a constraint for sustainable agriculture in smallholder farming systems in Ethiopia. In this study, crop productivity and soil organic matter buildup were compared in soils receiving locally made compost, applied either alone or in combination with NP fertilizer. The experiments had four treatments: full dose of compost (C), full dose of fertilizer (F), half compost and half fertilizer (CF), and unfertilized control (control). The full dose of compost was equivalent to 2.4 t ha(-1) organic matter. The field study was conducted on four farm fields in the village Beseku, each representing different sub-villages. Participating farmers were selected based on their willingness and an assessment of dedication to carry out the experiment. The experiments, a randomized complete block design with three replications, were replicated across four farm fields. The treatments were repeated for six cropping seasons (years), and data on soil nutrient status and crop (maize, wheat, potato, and faba bean) harvests were collected. In the 0-10 cm soil layer, pH was (P < 0.05) lower in the F treatments than in the C and CF treatments. Compared with the F treatment, the soil organic carbon (SOC) and total nitrogen stocks increased (P < 0.05) by 4.60 and 0.42 t ha(-1) in C treatment, and by 4.74 and 0.45 t ha(-1) in CF treatment. Treatment effects on crop harvests were significant (P < 0.05) for all crops grown across the sites and seasons. The highest maize yield was obtained from CF, with relative harvest of 178% compared with the control and 126% compared with F, but was comparable to C. For wheat and potato, the yields obtained from CF, C and F were comparable. For faba bean, CF had a relative harvest of 145% over the control. Maize harvest was in the order of CF > F> C> control in the initial season, CF > C> F> control in the next three consecutive seasons, and C> CF> F> control in the final year of the experiment. The overall combined yield was in the order of CF > C> F> control for maize and faba bean, CF > F> C> control for potato, and F> CF > C> control for wheat. The addition of either compost alone or in combination with NP fertilizer improved soil properties and crop productivity, compared with control and only fertilizer addition. Therefore, compost addition can serve as a complement to fertilizer use and reduce dependence on mineral fertilizer in low-input crop production system. The apparent synergy between compost and fertilizer addition needs further research in order to be explained. (C) 2014 Elsevier B.V. All rights reserved.
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| 4. |
- Engström, Annika
(författare)
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Lärande samspel för effektivitet : En studie av arbetsgrupper i ett mindre industriföretag
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- En viktig arena för samspel kring känsliga gränssnitt (marknad – konstruktion – produktion) i industrin är olika möten där arbetsgrupper kommer samman kring uppgifter. Syftet med avhandlingen är att bidra med kunskap om samspel som sker inom och mellan arbetsgrupper i deras hantering av uppgifter i mindre industriföretag (SME) och vilken betydelse samspelet har för lärande och effektivitet i verksamheten. Studien har närmare bestämt fokus på följande frågeställningar: 1. Vad karaktäriserar samspelet inom och mellan arbetsgrupper som det kommer till uttryck i olika möten? 2. Vilka faktorer underlättar respektive försvårar samspelet inom och mellan arbetsgrupper? 3. Vilka konsekvenser får olika typer av samspel för lärande och effektivitet i arbetsgrupper och i organisationer? Studien utgår från ett kritiskt realistiskt perspektiv på lärande i organisationer samt tidigare forskning om lärande, kommunikation och effektivitet i grupper och organisationer. Studien genomfördes under perioden 2008-2010 och var upplagd utifrån en kvalitativ och interaktiv forskningsansats. Datainsamlingen baserades på intervjuer, observationer av videofilmade möten samt frågeformulär. Analysen rör sig mellan två nivåer: samspel inom grupper samt mellan grupper på organisationsnivå. Samspelet inom och mellan grupper analyserades utifrån kontextuella faktorer och med fokus på i vad mån olika kommunikationsmönster kunde kopplas till olika typer av lärande och effektivitet i verksamheten. Ett rationalistiskt effektivitetsperspektiv utmanas till förmån för ett humanistiskt perspektiv där lärandet är en viktig aspekt. Tre slutsatser dras: Effektivitet grundar sig i att kommunikationsmönster och ledning anpassas efter det behov uppgiften för stunden kräver - utförande eller utveckling. Återkoppling och personliga länkar mellan grupper behöver översyn och ledningsrutiner för att underlätta samspelet. Diskrepanser (motsättningar, konflikter och störningar) som synliggörs i organisationen leder till utveckling. De som förblir i det dolda stör utförandet.
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| 6. |
- Iwald, Johan, et al.
(författare)
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Acidifying effect of removal of tree stumps and logging residues as compared to atmospheric deposition
- 2013
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 290, s. 49-58
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Tidskriftsartikel (refereegranskat)abstract
- Harvesting of stumps and logging residues for bioenergy can be expected to increase in the future. An increased biomass export from the forest will increase the biological acidification, measured as net cation (cations-anions) export. The aim of this study is to estimate the acidifying effect that various levels of harvesting of tree stumps and logging residues will have in Sweden, and compare this with the acidification currently caused by acid deposition. Estimations of yearly logging of Scots pine (Pinus sylvestris L), Norway spruce (Picea abies (L) Karst.) and birch (Betula spp.) on county-level were made based on scenario data from forestry consequence analyses and data from the Swedish National Forest Inventory. Data of cation and anion contents in tree parts were used to calculate the net cation extraction per area unit resulting from harvesting of stumps, stem-wood and logging residues, respectively. County-level data were merged into data for three different regions representing a gradient in deposition and climate.Results indicate that harvesting of stumps constitutes 13-24% of total (stumps + stem-wood + logging residues) excess cation extraction, depending on harvest intensity and tree species. Harvesting of logging residues constitutes 27-45% of total net cation extraction. The higher acidifying effect of logging residues can be explained by the higher contents of base cations in needles and branches compared to stem-wood. In a comparison between total net cation extraction by tree harvesting and maximum levels of current acid deposition the acidifying effect of pine harvesting is 57-108% of that of acid deposition, the acidifying effect of spruce harvesting is 114-263% while the acidifying effect of birch harvesting is 60-171%. Concerning the amount of acid input to the soil per unit heating value as biofuel, stump harvesting generates 12-27 eq H+ MWh(-1) while logging residue harvesting generates 39-66 eq H+ MWh(-1).Stump harvesting generates a higher heating value per area unit than logging residue harvesting and results in a lower acid input to the soil per unit heating value generated. Thus, from a strict nutrient balance and acidification perspective stump harvesting is a better alternative than harvesting of logging residues. (C) 2012 Elsevier B.V. All rights reserved.
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