Slip flow over structured surfaces with entrapped microbubbles

On hydrophobic surfaces, roughness may lead to a transition to a superhydrophobic state, where gas bubbles at the surface can have a strong impact on a detected slip. We present two-phase lattice Boltzmann simulations of a Couette flow over structured surfaces with attached gas bubbles. Even though the bubbles add slippery surfaces to the channel, they can cause negative slip to appear due to the increased roughness. The simulation method used allows the bubbles to deform due to viscous stresses. We find a decrease of the detected slip with increasing shear rate which is in contrast to some recent experimental results implicating that bubble deformation cannot account for these experiments. Possible applications of bubble surfaces in microfluidic devices are discussed.Comment: 4 pages, 4 figures. v2: revised version, to appear in Phys. Rev. Let

Quantitative characterization of pore structure of several biochars with 3D imaging

Pore space characteristics of biochars may vary depending on the used raw material and processing technology. Pore structure has significant effects on the water retention properties of biochar amended soils. In this work, several biochars were characterized with three-dimensional imaging and image analysis. X-ray computed microtomography was used to image biochars at resolution of 1.14 $\mu$m and the obtained images were analysed for porosity, pore-size distribution, specific surface area and structural anisotropy. In addition, random walk simulations were used to relate structural anisotropy to diffusive transport. Image analysis showed that considerable part of the biochar volume consist of pores in size range relevant to hydrological processes and storage of plant available water. Porosity and pore-size distribution were found to depend on the biochar type and the structural anisotopy analysis showed that used raw material considerably affects the pore characteristics at micrometre scale. Therefore attention should be paid to raw material selection and quality in applications requiring optimized pore structure.Comment: 16 pages, 4 figures. The final publication is available at Springer via http://dx.doi.org/10.1007/s11356-017-8823-

Suomen peltojen karttapohjainen eroosio-luokitus: Valtakunnallisen kattavuuden saavuttaminen ja WMS-palvelu

Eroosio on merkittävä maatalouden fosforikuormituksen aiheuttaja, ja peltojen eroosioriskin kehittyminen on yksi maatalouden kansainvälisistä ympäristöindikaattoreista. Maatalouden ympäristötoimenpiteiden suuntaamiseksi peltojen eroosioriskin arviointi on tärkeää ja peltolohkot, ja jopa niiden osat, on kyettävä luokittelemaan eroosioriskin suhteen. Tämän tutkimushankkeen tavoitteena oli tuottaa valtakunnallisesti kattava järjestelmä Mapero hankkeessa (2010-2013) kehitetylle kartta-pohjaiselle RUSLE -mallille. Jotta mallia ja siihen perustuvia palveluja voitaisiin jatkossa hyödyntää neuvonnassa ja mahdollisesti tukipolitiikassa, on tasapuolisuuden vuoksi välttämätöntä saavuttaa koko maan kattavuus. Maanmittauslaitoksen suunnitelmien mukaan laserkeilausaineistopohjainen 2m:n erotuskyvyn korkeusmalli kattaisi koko Suomen vuonna 2019. Mapero 2 -hankkeessa kehitettiin tuotantojärjestelmä, jonka avulla tarkkaan korkeusmalliin pohjautuvat eroosioherkkyyskartat voidaan luoda koko Suomen alueelle tehokkaasti. Uusi suurteholaskentatekniikka myös mahdollistaa mallin nopean päivittämisen tarvittaessa ja mahdollisimman suuren automaation. Järjestelmän laskentaperiaatteet on kuvattu tieteellisessä julkaisussa. Karttojen kvalitatiivinen tarkkuus (ts. suhteellisen eroosioriskin esiintyminen) on arvioitu hyväksi niin koekentiltä saatujen tulosten kuin viljelijöidenkin antaman palautteen perusteella. Kvantitatiivinen tarkkuus (t/ha/v) sen sijaan ei ole ollut yhtä hyvä. Euroopan komission yhteinen tutkimuskeskus (JRC) julkaisi vuonna 2015 Euroopan oloihin säädetyn RUSLE2015 – mallin, jonka käyttöönotto paransi kvantitatiivista tarkkuutta verrattuna RUSLE-malliin. Hankkeen aikana laaditussa julkaisussa ”Eva-luation of RUSLE2015 erosion model for boreal conditions” arvioitiin RUSLE2015 mallia kuudella suomalaisella koekentällä (Geoderma Regional lehti). Tuotetut kartat ovat nyt RUSLE2015-mallin mukaisia ja näin yhteensopivia EU:n laajuisten karttojen kanssa. Hankkeessa valmistuva kartta-aineisto annetaan vapaasti hyödynnettäviksi Luonnonvarakeskuksen tulevan WMS - katselupalvelun kautta, mutta peltolohkoon liittyvä ominaisuustieto, t/ha/v ja sen avulla laaditut luokitukset voidaan tarvittaessa antaa vain viljelijöiden ja neuvojien käyttöön esim. Vipu-palvelun kautta. Uusi malli soveltuu käytettäviksi yksittäisillä maatiloilla ja vesiensuojelun kannalta kriittisillä valuma-alueilla kohdentamaan toimenpiteitä kustannustehokkaasti.201

Suomen peltojen maalajit, multavuus ja fosforipitoisuus : Vuodet 1996–2000 ja 2005–2009

Julkaisuun on koottu tietoja Suomen peltomaiden muokkauskerroksen lajitekoostumuksesta (maalajista), orgaanisen aineksen määrästä (multavuudesta), happamuudesta ja maan viljavuusfosforipitoisuudesta vuosilta 1996–2000 (noin 880 000 maanäytettä) ja 2005–2009 (noin miljoona näytettä). Maanäytteet ovat viljelijöiden tai maatalousneuvojien ottamia osana vapaaehtoista maatalouden ympäristökorvausta. Aiemmissa yhteenvedoissa tiedot on esitetty jakaumien keskilukuina ja varsinaiset jakaumat vain kuvina ilman jaottelua maalajien mukaan. Tässä julkaisussa tiedot on raportoitu maalajiryhmittäin koko valtakunnan, ELY-keskusten ja yksittäisten kuntien tasolla. Kuntatason tietoja on mahdollista koota esimerkiksi vesistöjen valuma-alueita kattaviksi tietueiksi. Fosfori on tärkeä kasvinravinne ja samalla kriittinen maatalouden vesistövaikutusten kannalta. Raportin liitetaulukoissa esitetään maan viljavuusfosforin keskiarvot, mediaanit ja jakaumat. Fosforilukujen jakaumat esitetetään tiiviisti summajakaumina, joista voidaan palauttaa alkuperäisten jakaumien muodot. Palautetut jakaumat vastaavat alkuperäisiä jakaumia sitä paremmin, mitä suurempaan tulosjoukkoon tiedot perustuvat. Summaries based on large data sets on soil test phosphorus (STP) concentrations, soil types, organic matter contents and pH of Finnish agricultural soils have been earlier published at intervals, and they cover data analysed from 1955 to 1985. This report is another publication in this tradition and it covers two more recent 5-yr periods, 1996–2000 and 2005–2009. Data for our report were obtained from commercial soil testing laboratories, and includes results of about 880,000 soil samples for the period 1996–2000, and about one million samples for the period 2005–2009. The Finnish Agri-Environmental Programme (FAEP), in effect since 1995, stipulates farmers to sample their fields every 5 years in a commercial soil testing laboratory. Hence, data of the two reported 5-yr periods should, by and large, include data from the same field population. Commitment to the FAEP has been high ever since the Programmes were launched; FEAP regulations cover over 90% of the farms and about 95% of the agricultural land in the country. Agricultural land in Finland comprises of about 2.3 million hectares, so one sample in our dataset would on average correspond to about 2.5 hectare field area. In the earlier statistics, STP were reported as means and median values, distributions were only shown in figures, and the STP distributions of different soil types were not separable. In this report, we tabulate STP distributions according to soil types as cumulative frequencies. These can be backtransformed to original distributions with one STP unit resolution; the larger are the number of data and the narrower it’s distribution over the STP scale, the better back-transformed distributions correspond to the original ones. Data are made available for different scales: the whole country, administrative regions, and individual municipalities. The municipality level data allows building subsets according to river or lake catchment borders, as example.201

Fertilizer and soil conditioner value of broiler manure biochars

Peer reviewe

A novel solution for utilizing liquid fractions from slow pyrolysis and hydrothermal carbonization - Acidification of animal slurry

Pyrolysis and hydrothermal carbonization (HTC) have recently gained much interest in the field of biomass processing. This is due to the process flexibility with respect to raw materials and the range of potential applications proposed for the end products. In addition to the main product, biochar, the processes yield a liquid fraction that has turned out to be challenging to productize. Considering the feasibility of the thermochemical conversion technologies, it is crucial that all the produced fractions can be utilized reasonably and no waste fractions expensive to dispose remain. In spite of active research and development work, unambiguous uses for the liquid fractions have not been recognized yet. Please click on the file below for full content of the abstract

Characterization of biochar pore structure with X-ray tomography

Biochar use as soil amendment can influence both physical and chemical properties of soil. The effects of biochar depend on the raw material from which biochar is derived as well as on the used processing technology and process conditions. One commonly highlighted benefit of biochar application is improved water retention properties of soil. Biochar may affect water retention in direct or direct way. In direct mechanism water is stored and held in the biochar pores while in indirect mechanisms biochar contributes to the soil structural development (aggregation). Please click on the file below for full content of the abstract

Are there environmental or agricultural benefits in using forest residue biochar in boreal agricultural clay soil?

Short-term agronomic and environmental benefits are fundamental factors in encouraging farmers to use biochar on a broad scale. The short-term impacts of forest residue biochar (BC) on the productivity and carbon (C) storage of arable boreal clay soil were studied in a field experiment. In addition, rain simulations and aggregate stability tests were carried out to investigate the potential of BC to reduce nutrient export to surface waters. A BC addition of 30 t ha−1 increased soil test phosphorus and decreased bulk density in the surface soil but did not significantly change pH or water retention properties, and most importantly, did not increase the yield. There were no changes in the bacterial or fungal communities, or biomasses. Soil basal respiration was higher in BC-amended plots in the spring, but no differences in respiration rates were detected in the fall two years after the application. Rain simulation experiments did not support the use of BC in reducing erosion or the export of nutrients from the field. Of the C added, on average 80% was discovered in the 0–45 cm soil layer one year after the application. Amendment of boreal clay soil with a high rate of BC characterized by a moderately alkaline pH, low surface functionalities, and a recalcitrant nature, did not induce such positive impacts that would unambiguously motivate farmers to invest in BC. BC use seems unviable from the farmer's perspective but could play a role in climate change mitigation, as it will likely serve as long-term C storage.202