Browsing by Subject "soil"

Tämän tutkielman tavoitteena oli suunnitella, rakentaa ja testata helposti asennettava ja käytettävä mittauslaitteisto, joka pystyisi mittaamaan reaaliajassa yksinkertaisia suureita, joiden avulla olisi mahdollista arvioida renkaiden ja maaperän välisen kontaktin vaikutusta maataloustraktorien liikkuvuuteen. Kehitetty mittauslaitteisto perustuu Arduino Uno mikrokontrolleriin kytkettyihin kiihtyvyys- ja etäisyys antureihin sekä traktorin väylätietojen lukemiseen. CAN-väylän lukeminen ja tietojen tallentaminen tapahtui RaspberryPi pienoistietokoneeseen liitetyn CAN-väylä kortin avulla. Anturit kalibroitiin ja niiden herkkyys tarkistettiin ennen kokeiden suorittamista peltoajossa. Kiihtyvyysanturit sijoitettiin traktorin taka-akselin päälle molempiin päihin koteloihin ja etäisyysanturit kiinnitettiin akselin takapuolelle. Kaikkia antureita luettiin RaspberryPi:n sarjaporttiin liitetyn Arduinon välityksellä ja tiedot tallennettiin tehdyllä python ohjelmalla. Raspberry Pi valittiin tietokoneeksi sen vähäisen tilavuusvaatimuksen, alhaisen hinnan sekä liitäntöjen monipuolisuuden vuoksi. Pellon ominaisuuksia seurattiin kuukausittain suoritetuilla penetrometri mittauksilla sekä maahan upotetuilla SoilScout antureilla, jotka kertoivat maan kosteuden sekä lämpötilan kyseisessä syvyydessä reaaliajassa. Tämän tarkoituksena oli saada selville pellossa kasvukauden aikana tapahtuvat muutokset, jotka vaikuttaisivat myös traktorin liikkumiskykyyn. Mittaukset onnistuivat hyvin ja tulokset arvioitiin olevan laadultaan luotettavia, joten ne tarjoavat monia muita mahdollisuuksia tulevaisuudessa. Tulokset osoittivat selvästi traktorin liikkuvuuteen vaikuttavat tekijät ja maanmuokkauksen eri vaiheet pystyttiin havainnoimaan. Tulevaisuuden haasteina säilyvät edelleen suuren tietomäärän suodattaminen sekä mittauslaitteiden soveltaminen jatkotutkimuksissa. Työssä kehitetty mittauslaitteisto soveltuu tarkoitukseensa mittaustarkkuuden sekä kustannustehokkuutensa puolesta hyvin. Tulevaisuudessa parempaan tarkkuuteen voitaisiin päästä tarkemmilla mittalaitteilla sekä tämän työn pohjalta saaduilla tiedoilla.

Climate change and the degradation of soils are global and increasingly prevalent issue. Pyrolyzed organic materials, biochars, are progressively studied as a promising tool to sequester carbon in soils, whilst also improving soil properties. It is important to understand how different biochars affect other integral features of the soil ecosystem, such as soil biota, before they are utilized. Biochars are currently mostly utilized in agricultural settings; in order to extend their use for carbon sequestration in forest soils, more research regarding different biochars in forest settings is necessary. This Master’s thesis was conducted as literature review and meta-analysis of existing forest field studies in which the effect of biochars on soil biota was measured. Two sources (the University of Helsinki digital library collection (Helka), and internet search engine Google Scholar were used. From the studies gathered, soil respiration and microbial biomass carbon (MBC) were used as variables to estimate the effect of biochars on soil biota. Due to the scarcity of existing research, experimental conditions included in this thesis are diverse, including plantations, three climatic regions (boreal, temperate and subtropic) and different biochar types. Subgroups were formed from received data according to different treatments and standard mean differences (SMD) were compared. Contrary to the hypothesis, within this meta-analysis, soils amended with biochars demonstrated either no change or decreased soil respiration and MBC. On average, soil respiration did not show any significant change to biochar amendment, whilst MBC decreased significantly in some subgroups: short-term studies (<= 12 months), small difference in pH between soil and biochar (< 4), low pyrolysis temperature of biochar (<= 450 ˚C) and small quantity of biochar applied (< 10 t/ha). The decreasing in MBC was not consistent and diminished with increasing quantity of biochar and in study periods over 12 months. Given that biochars do not seem to have clear effects on microbial forest soil biota or microbial respiration, the application of biochars to forest soils has its potentials. However, larger scale use should be considered with caution, and further research is necessary.

The black truffle (Tuber melanosporum) is an inscrutable mushroom. It is widely believed that the physico-chemical properties of a soil are of great importance for it. Its cultivation in the Auvergne region in France is fraught with impediments. Gérard Chevalier (Institut National de la Recherche Agronomique) postulates that soils with higher than 40% clay content would be inauspicious, unless moderated by a compensating effect from increased rock fragments content. The work undertaken should substantiate this hypothesis, and furthermore take inventory of the mycorrhizal status of the 25 truffle orchards, some of which are thirty years old. The results show that 50% of the plantations still house Tuber melanosporum mycorrhizae. Statistical analysis of the collected information vis-à-vis soil analyses and interpretations of soil profiles in relation to production, shows that a high clay content diminishes the chances of success. The results attained are not sufficient to assert the compensatory effect of soil stoniness. This study moreover highlights the significant roles of total carbonate, active carbonate, phosphorus and potassium contents. These results should be considered with caution, since the small size sample consists of “instances” with heterogeneous characteristics, and the soil analysis methodology does not take into account various environmental factors, whose impact could well be significant (for example light conditions in the orchards). Despite these limitations, this study conveys a dual adage, both scientific and technical. For researchers, it brings some additional insights. For those who wish to produce Tuber melanosporum, it confirms an existing potential in Auvergne. By and large, it illuminates the murky manifest countenance of the black truffle.

Biogeography is a crucial aspect to ecological studies, as an ecosystem is comprised of the physical habitat, the organisms living there, and the interactions of these components. Community structure, and therefore functioning, are inherently of a spatial nature. Spatial structure of populations is often crucial basic knowledge for understanding the evolutionary history, dispersal patterns, and resilience of any given species. One aspect of spatial structure, and the topic covered in this study, is community distance decay, or the rate at which community similarity decreases with physical distance. More of the landscape is constantly being altered by humans on a large scale, so it is increasingly important to understand the effects that these anthroprogenic changes to the environment has on local populations. Studying community distance decay helps form understanding of dispersal and establishment limitations for different organisms, which is necessary for mitigating biodiversity loss. Many studies show that habitat fragmentation and loss has greatly impacted the structure of plant and animal communities, but there has been much less focus on fungal communities. There’s no certainty that fungi is impacted in the same ways, given the different lifestyles and dispersal methods, so the aim of this study is to contribute to the much needed research on fungal community structure at various scales. This aim is addressed by examining fungal community distance decay from small scale of a couple kilometers or less to a fairly large scale encompassing a landscape of primarily urban, forest, and agricultural areas. The five main localities of sampling were in middle and southern Finland: Helsinki, Lahti, Tampere, Jyväskylä, and Joensuu. Sampling locations and plot design were chosen to allow the comparison of communities separated by a mosaic, as well as along a short rural to urban gradient, to assess the effects of habitat type. From each location, six plots were decided, two in urban core, one in urban edge, two in natural core, and one in natural edge. The role of dispersal ability and functional traits in distance decay is also studied by comparing results from two different methods of fungi sampling, which were collecting spores from the air using cyclone samplers, and taking soil cores to gather fungal biomass. All samples were DNA analysed with high-throughput sequencing and the results from the DNA barcoding were used to create OTU clusters, by which the 30 plots could be compared through relative abundances of OTU’s. I determined the similarity of fungal communities using an analysis of similarity (ANOSIM) test in R, where all possible variables (site, habitat type, sample type) were used as a grouping in individual tests, thereby indicating which variable is associated with highest community difference. I also determined the differences in functional groups and major taxonomic levels among locations and sampling method using interactive taxanomic (KRONA) charts. Results showed that there are differences in fungal community structure among habitat type and sampling type. However there was greater difference at the level of plots than site locations, so clear patterns of strong community distance decay with physical distance was not measured in this study. The results suggest that fungal communities can be fairly impacted by human caused habitat change, and individual characteristics, such as dispersal methods or lifestyle, effect the rate of community distance-decay. This provides a valuable early insight into fungal community patterns, which need deeper study to understand the complexities and mechanisms behind them.

Radium (Ra) is a naturally occurring radioactive metal, which is formed by the decay of uranium-238 and thorium-232 in the environment. In nature, radium occurs at trace levels in virtually all water, soil, rock and plants. 226Ra-, 228Ra, 224Ra, and 223Ra-isotopes are the most common isotopes of radium, and all isotopes are radioactive. The aim of the work was to study the behavior of radium in nature. In general, radium isotopes with variable activity concentrations in water and solid samples such as soil, and sediment can be measured with alpha- or gamma spectrometry or liquid scintillation counting (LSC). In this work, the measurements were done using gamma spectrometry with a Ge-detector, which is a semiconductor detector made of germanium. In addition, a very low level liquid scintillation spectrometer (Quantulus 1220) was also used. The determination of the PSA value (Pulse Shape Analysis) was successful and was determined experimentally with a Ra-226 standard sample. The activity of the Ra-226 standard sample obtained with Ge detectors was almost of the same order of magnitude as both theoretically and experimentally determined activities. The determined Ra-226 activities in water samples with gamma spectrometry were in good agreement with the activities obtained by LSC using α/β-discrimination

Soil contamination can result in soil degradation, bring great loss to agricultural production and pose threat to human health. Many of the soil contaminants are petroleum hydrocarbons (PHCs) derived from crude oil or refined petroleum products. Phytoremediation which relies on plants and their associated microorganisms to remove contaminants is cost-effective and applicable to treat a wide variety of soil contaminants. Besides trees, herbaceous plants are widely and effectively used in the remediation of PHC contaminated soils. Greenhouse studies have found that Galega orientalis co-inoculated with Rhizobium galegae and plant growth promoting bacteria (PGPB) benefiting soil with nitrogen fixation is able to remediate PHC contaminated soils. The FP7 ‘‘Legume-Futures’’ remediation field experiment was established at Viikki experimental farm, University of Helsinki in 2009 in order to test the practical applicability of the greenhouse results in a field scale. In a split-plot design, crop (Galega orientalis, Bromus inermis, Galega orientalis + Bromus inermis, bare soil control) treatments were designated the main factor, oil (±) and PGPB (±) the sub-factors in factorial combination with four replicates. Soil samples were taken at four time points from July 2009 to May 2011. Soil total solvent extractable material (TSEM) was extracted and measured by the gravimetrical method as a direct indicator of oil content. Physiochemical properties (pH, EC, total C and N and C/N ratio) of soil samples (taken in July 2009 and Nov. 2010) were determined. The losses of total C and TSEM between July 2009 and Nov. 2010 were calculated to estimate the differences crops and PGPB brought in oil treated plots. Crop dry matter yields were determined. The changes of soil microbial population, bacterial diversity and community structures were studied by the 16S rRNA gene based community fingerprinting method LH-PCR. Bioremediation and physical removal were the main processes of oil removal in our experiment. Climate factors (e.g. temperature and precipitation) had an overriding influence on the removal of oil in our study. Soil condition with a neutral pH and C/N ratio in our field was optimal for biodegradation of hydrocarbons. The changes in soil microbial total DNA, diversity and community structure were sensitive indicators of soil contamination and recovery. Crop (Galega orientalis and Bromus inermis) and PGPB treatment had no significant effect on soil physiochemical and microbiological properties nor on the removal of oil in our experiment, which largely differed from our hypothesis. Resource competition between crops and microorganisms might have resulted in the better oil remediation in bare soils than in vegetated soils. Nevertheless, crops were found to have a high tolerance to oil contamination and surprisingly, the oil contamination seemed to increase the growth of both crop species. Bromus in mixture plots (without commercial nitrogen fertilization) had better yield than in pure plots (with commercial nitrogen fertilization) as a result of biological nitrogen fixation of Galega orientalis and Rhizobium galegae. Therefore the mixture of galega and bromus can be suggested to be applied in future phytoremediation projects.