Modifying soil structure using plant roots

Compaction in the subsoil may lead to permanent yield losses. The main objectives of this thesis was to test the possibility of using plant roots to modify soil structure and to use laboratory screening methods to find plant species suitable for penetrating strong soil. Two laboratory screening methods were tested. The first method used soft and hard wax layers installed in sand cores. The proportion of roots penetrating the hard relative to the soft layer was highest for lucerne, intermediate for chicory, lupin and red clover, and lowest for barley. The second method used natural soil compacted by different vertical stresses. Measurements of root length density showed that lucerne had a greater ability to establish a deep root system in compacted soil than barley and lupin. A field experiment was carried out to test the possibility to use plant roots to modify subsoil structure. The complete area of all plots except the control plots were compacted by a dump truck (weight 30 Mg) prior to the start of the experiments. The plant species studied were lupin (Lupinus luteus L.), lucerne (Medicago sativa L.), red clover (Trifolium pratense L.), tall fescue (Festuca arundinacea L.), chicory (Cichorium intybus L.) and barley (Hordeum vulgare L.). Tall fescue had the highest root length density (RLD) at 30-35 cm depth, but RLD of chicory and lucerne were also fairly high. Chicory had the largest effect on subsoil structure, as estimated by saturated hydraulic conductivity (Ksat) at 30-35 cm depth, closely followed by lucerne. Abundance of earthworms was related to tillage intensity and was consistently higher in plots of perennial crops. The influence of earthworms on Ksat was lower than that of plant roots. Two field experiments were carried out to study mechanical subsoiling in combination with: a) incorporation of slaked lime and b) the use of plant roots as reinforcement of the loosened soil. Incorporation of slaked lime increased stability of the modified soil structure. Growing crops of lucerne prolonged the effect of subsoiling on Ksat. Conventional mechanical subsoiling gave short-lived results

Fabrication of a light-weight SOFC using ceramic fibre paper as substrate

A novel method for the fabrication of a light-weight solid oxide fuel cell (SOFC) has been evaluated at Catator. This was conducted in order to lower the weight and thus cost of an unmanned aerial vehicle. The main aim for this thesis was to achieve a thin, dense and crack-free electrolyte using a ceramic fibre paper as substrate. This paper was impregnated with colloidal solutions and pressed to planar and tubular structures to achieve a porous substrate for the SOFC. Nickel was incorporated and a bilayer was coated on top of the substrate to create a flat surface onto which a thin electrolyte and cathode layer could be applied. All steps were followed by heat treatments to enable drying, calcination or sintering processes. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the characteristics of the electrolyte and the chemical make-up of the SOFC respectively. Optical microscopy was used extensively to get an understanding of how the different experimental methods were affecting the microstructure. A system test was performed by constructing a test oven but failed due to malfunctions which was probably caused by short circuits. The results from the SEM indicates that the electrolyte was quite dense but not free from cracks and the EDS shows an unevenly distributed anode. If the desired outcome is to be achieved using similar methods an automated process need to be implemented since it is currently too time consuming to be cost effective. A weight decrease of 50 % was observed compared to a conventional SOFC previously used by Catator, so if a working method could be achieved there could be decreases in cost for mobile applications.A solid oxide fuel cell’s journey to a light flight. Layering and coating of a multi-impregnated ceramic fibre paper to ultimately form a SOFC unit. Also, there will be spaghetti carbonara and cake. Fuel cells can in a long perspective contribute to decrease the dependence on fossil fuels mainly due to two reasons. Firstly, it has a higher efficiency relative to combustion engines. Secondly, hydrogen, the most common fuel, can be produced from water, using sustainable energy sources such as wind and solar power. However the most common source of hydrogen is currently from fossil fuels. What if a SOFC could be made with a lighter weight? This would have a great effect on mobile applications such as drones for a number of reasons. A lower weight would result in less fuel consumption. This in turn would make it more cost effective and increase the drone’s air time. The technique attempted in this thesis could, when successful, contribute to cheaper manufacturing of portable energy devices. For instance you could recharge your laptop or your cell phone using this technology. Imagine a network of spaghetti looking fibres, randomly distributed yet connected to each other. This is how my starting material looked like at 10X magnification. How was I supposed to turn this carbonara in to a high-tech energy device? In this work I assessed a method for the construction of a light-weight SOFC. The low weight is achieved by using a ceramic fibre paper. Through a series of vacuum impregnations followed by multiple layer applications, the paper was transformed to a SOFC. Each step ended with heat treatment. It was like making a ridiculously complex cake. The SOFC consists of three main parts: anode, electrolyte and cathode. In order for the anode to work properly it needs to conduct electrons and be catalytically active. This was achieved by incorporating metallic nickel into the structure. However, energy dispersive spectroscopy analysis showed that the anode might have an uneven distribution of nickel. To verify the functionality of the fuel cell the electrolyte, which can be seen as the heart of the fuel cell, was investigated. This was done by a scanning electron microscope. It was seen that the electrolyte surface contained small cracks which might cause gas diffusion between the anode and cathode. For the SOFC to work properly there should not be any mixing of the gases. A performance test was conducted in order to see if it worked. However, due to malfunctions in the system, no conclusions could be drawn from the test. For future improvement, an automated process should be developed, since the method is currently too time consuming to be economically viable

Improvements of pesticide handling in greenhouse situations

The use of pesticides in greenhouses has often been regarded, formally at least, as if the greenhouse was a closed system, isolated from surrounding soil, air, and water. Recently, several pesticide residues studies in watercourses have been conducted, showing pollution that could be related to greenhouse production. In a previous project, several potential point sources were identified. The objective of this project was to transform identified shortcomings within the field of point sources, into improvements; to reduce the risk of accidents and minimize the consequences. A filling/mixing/cleaning station was developed as a ‘mock-up’ and tested by growers and advisers, and after that, further improved. An important part of the design was to facilitate the handling work and, in this way, reduce the temptation to handle pesticides at inexpedient places. A promising idea from users themselves is also described; an attachment to standard sprayer tanks, to minimize spillin

Förbättring av hantering av bekämpningsmedel i växthus

Användningen av bekämpningsmedel i växthus har tidigare, åtminstone formellt, betraktats som om det skedde i ett slutet system, isolerat från omgivande mark, luft och vatten. Under senare år har dock flera mätningar av bekämpningsmedelsrester genomförts i vattendrag nedströms växthus. Resultaten gjorde det troligt att växthus bidrar till föroreningar av mark och vatten. Det har inte klarlagts om den dominerande orsaken är punktkällor eller diffusa källor. Detta projekt inriktas på punktkällor, som har samband med hantering av bekämpningsmedel (dvs alla hanteringsmoment utom själva sprutningen). I ett tidigare projekt identifierades punktkällor med riskabel hantering i ett antal verkliga situationer. Skillnader påvisades mellan företag, storlek, produktionstyp, ålder av lokaler, etc. Det framkom riskabla situationer med potential till förbättringar, men också många goda exempel och rimliga lösningar. Syftet med det nu rapporterade projektet (Säkrare hantering av bekämpningsmedel i växthus, del II) har varit att omvandla de identifierade bristerna till praktiskt genomförbara förbättringar, för att minska risken för olyckor och minimera konsekvenserna för eventuellt läckage av bekämpningsmedel i växthus. Olika situationer och problem har analyserats och generaliserats. Diskussioner och intervjuer med växthusodlare har genomförts för att finna flera goda exempel. Studien har omfattat följande förbättringsförslag för hanteringen av bekämpningsmedel: • Påfyllnadsstation: En station för fyllning/blandning/rengöring utvecklades som en fullskalemodell. Den testades av odlare och rådgivare, som föreslog ytterligare förbättringar. En viktig del av utformningen var att underlätta hanteringsarbetet och på detta sätt minska frestelsen att hantera bekämpningsmedel på olämpliga platser. I detta förbättringsförslag har goda exempel från odlare identifierats och modifierats. • Mobil påfyllnadsplats: För större anläggningar med samma kultur, där flera spruttankar fylls under en behandlingsomgång, föreslogs ett tillbehör till växthussprutan för att förebygga, alternativt samla upp oavsiktliga utsläpp. • Central placering av påfyllnadsplatsen: Påfyllnadsplatsen (inklusive lagring av bekämpningsmedel) föreslogs bli placerad centralt i växthusanläggningen, för att minska riskabla transporter. • Förbättrad sprutdesign: Diskussioner skedde med spruttillverkare för att införa ett skyddande skal för elektriska motorer, etc, så att växthussprutan kan rengöras på ett säkert sätt. • Undvikande av brunnar: Slutligen rekommenderar vi starkt att sprutoperatörer undviker all uppmätning och blandning i närheten av vaskar och golvbrunnar, anslutna till diken eller avlopp

Fakta om växtskyddsmetoder för småskalig ekologisk produktion

Att skydda odlingen mot växtskadegörare är helt avgörande för en hållbar produktion. I ekologisk produktion är förebyggande växtskyddsmetoder basen. Dessa kompletteras med biologiska metoder, allmänkemikalier och i vissa fall med ett fåtal kemiska substanser med naturligt ursprung. Grunden till ett gott växtskydd är densamma i alla odlingssystem, men i ekologiska odlingssystem är inga ogräsmedel tillåtna och ytterst få växtskyddsmedel används. Detta faktablad ger korta fakta om växtskyddsmetoder i ekologisk produktion i Sverige

Lexical and semantic development in children with cochlear implants

Introduction: Two important events have changed the prerequisites for children with severe-profound hearing impairment (HI). The first is the universal newborn hearing screening (UNHS) that enables early detection and identification of congenital or early- acquired HI. The second factor is the possibility of cochlear implant (CI) intervention at younger ages. There has been little previous interest in studying lexical-semantic ability in the new generation of children with CI who are implanted at a fairly young age, often bilaterally, in relation to the cognitive capacities that influence on use and knowledge of words. Aim: The general aim was to explore lexical-semantic ability and development in a group of school-aged children with CI and in comparison with age-matched normal hearing (NH) children. Method: The four studies examined different aspects of lexical-semantic ability in children aged 6-9 years. The cohort consisted of 34 children with CI and 39 age- matched children with NH (Study I-IV). In addition, two other clinical groups: children with language impairment (LI) (n=12) and children with autism spectrum disorder (ASD) (n=12) participated in Study II. A broad test battery was used, especially examining lexical-semantic ability but also non-verbal cognitive ability as well as phonological and learning ability. An error response analysis was conducted on a picture-naming test and a linguistic cluster analysis was performed on two different word fluency tasks with the purpose of examining strategies that the participants used when they retrieved words from their long-term-memory (LTM). Study IV had a partly longitudinal approach where a subgroup of children with CI (n=18) were examined more closely over time and in comparison with other age-matched groups at the age of 8-9 years. Statistical analyses were made primarily to examine group differences. Results: Many children with CI reached age-equivalent lexical-semantic ability at the age of 8-9 years. Semantic knowledge and non-verbal cognitive ability predicted grammatical sentence understanding (GSU) in both groups (CI and NH). Children with CI used age-appropriate learning strategies and had similar cognitive capacities necessary for managing use and knowledge of words as NH controls. In addition, children with CI showed better outcome than children with LI or ASD. However, an atypical developmental pattern was found in Study II where children with CI had better expressive than receptive vocabulary compared to typically developed children with NH. Also, the variation of the outcome was overall greater in children with CI (Study I- IV). An age-related CI subgroup-pattern was found in Study I that lead to the planning of a follow-up study, also examining retrospective, early spoken language development (Study IV). Children in the subgroup with higher group mean age at 1st CI had significantly poorer results on receptive vocabulary, phonemically based letter word fluency and GSU than NH controls. Despite of these results, the whole sample of children with CI had an age-appropriate level of expressive vocabulary and semantic feature knowledge. Semantic knowledge was demonstrated as an adequate ability to recognize semantic features and to use semantically relevant responses when lacking the lexical term while naming pictures (Study III). Children with an younger group mean age at 1 CI had better early expressive language use, two years after CI-operation, than the other subgroup, and they were also able to catch up after school entry on receptive vocabulary and phonemically based letter word fluency ability (Study IV). Conclusions: Children with CI and typical non-verbal cognitive ability did not have specific deficiencies in cognitive processing of lexical-semantic items, but some children had deficiencies with phonological and lexical-semantic knowledge. The results indicate that age at 1st CI is important as a starter engine of spoken language development through listening, but that other more linguistic-related factors and strategies also are important for development of lexical-semantic ability. There was a greater variation of the spoken language outcome in children with CI, and some atypical developmental patterns were found in the sample. Future studies of lexical-semantic ability in children with CI should therefore have a longitudinal approach and also explore the influence of environmental factors

Environmental Assessment of Upgrading Horticultural Side Streams—The Case of Unharvested Broccoli Leaves

: To facilitate transition to a sustainable food system, it is necessary to address food losses. A large proportion of waste occurs during primary production, with large quantities of edible crop parts left in the field at harvest. One such product is broccoli, where normally only around one-third of the edible parts of the plant are harvested in Sweden. Much of the broccoli plant consists of edible leaves and this side stream represents an unused resource with great potential. This study assessed the potential environmental savings that can be achieved by utilising broccoli side streams as a powder in soups and bread. Consequential and attributional life cycle assessments were conducted, based on scenarios relevant for growers in southern Sweden. The results showed that the scenario with the largest saving potential was to process the broccoli side streams into a powder for use in broccoli soup. The main saving was due to substitution of imported broccoli powder, which was assumed to be produced from broccoli florets using a more fossil-based energy mix. The second best scenario was to use the side-stream broccoli powder as a wheat substitute in bread but, since wheat flour is less resource-demanding than imported broccoli powder, the emission savings were lower in this case. However, replacing wheat flour with a vegetable-based product could provide additional health benefits that are important in achieving a healthy, locally available, and environmentally friendly diet suitable for a sustainable food system

Greenhouse production contributes to pesticide occurrences in Swedish streams

Greenhouse and other covered cultivation systems have increased globally over the past several decades, leading to considerably improved product quality and productivity per land area unit. However, there is a paucity in information regarding the environmental impacts of covered production systems, especially regarding pesticides entering the surrounding environment. Aiming to address this knowledge gap, we collected grab samples downstream of greenhouses from seven Swedish streams every 14 days during a 12 month period. In three of the streams, samples were also taken upstream of the greenhouses and in four of the streams time-integrated samples were collected by TIMFIE samplers in the period between grab sampling occasions. The samples were analyzed for 28 substances (27 that were permitted for use in greenhouse production systems in Sweden and one degradation product to a permitted substance). Pesticide use journals were collected from the greenhouse producers for the 12 month period. The results were examined for indications of greenhouse contributions to detection frequencies, maximum and average concentrations, and potential ecotoxicicity in several ways: (1) comparing locations downstream of greenhouses with registered use of a substance with those without registered use, (2) comparing results from this study with those from the Swedish environmental monitoring program of pesticides in surface water from catchments with no greenhouses from the same period and region, (3) comparing concentration trends with registered pesticide application times in the greenhouses, and (4) comparing up-and downstream concentrations. The results strongly suggest that greenhouse applications do contribute to pesticide occurrences, maximum and median concentrations for most of the pesticides included in this study, and to potential toxicity to aquatic organisms for several of them, most notably imidacloprid, acetamiprid, carbendazim, and pirimicarb

Correlates of Orthographic Learning in Swedish Children With Cochlear Implants

This study set out to explore the cognitive and linguistic correlates of orthographic learning in a group of 32 deaf and hard of hearing children with cochlear implants, to better understand the factors that affect the development of fluent reading in these children. To date, the research about the mechanisms of reading fluency and orthographic learning in this population is scarce. The children were between 6:0 and 10:11 years of age and used oral language as their primary mode of communication. They were assessed on orthographic learning, reading fluency and a range of cognitive and linguistic skills including working memory measures, word retrieval and paired associate learning. The results were analyzed in a set of correlation analyses. In line with previous findings from children with typical hearing, orthographic learning was strongly correlated with phonological decoding, receptive vocabulary, phonological skills, verbal-verbal paired-associate learning and word retrieval. The results of this study suggest that orthographic learning in children with CI is strongly dependent on similar cognitive and linguistic skills as in typically hearing peers. Efforts should thus be made to support phonological decoding skill, vocabulary, and phonological skills in this population