Browsing by Subject "MICROBIAL BIOMASS"

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  • COST action TD1107 (2017)
    Key priorities in biochar research for future guidance of sustainable policy development have been identified by expert assessment within the COST Action TD1107. The current level of scientific understanding (LOSU) regarding the consequences of biochar application to soil were explored. Five broad thematic areas of biochar research were addressed: soil biodiversity and ecotoxicology, soil organic matter and greenhouse gas (GHG) emissions, soil physical properties, nutrient cycles and crop production, and soil remediation. The highest future research priorities regarding biochar's effects in soils were: functional redundancy within soil microbial communities, bioavailability of biochar's contaminants to soil biota, soil organic matter stability, GHG emissions, soil formation, soil hydrology, nutrient cycling due to microbial priming as well as altered rhizosphere ecology, and soil pH buffering capacity. Methodological and other constraints to achieve the required LOSU are discussed and options for efficient progress of biochar research and sustainable application to soil are presented.
  • Kastovska, Eva; Strakova, Petra; Edwards, Keith; Urbanova, Zuzana; Barta, Jiri; Mastny, Jiri; Santruckova, Hana; Picek, Tomas (2018)
    Peatlands are large repositories of carbon (C). Sphagnum mosses play a key role in C sequestration, whereas the presence of vascular plants is generally thought to stimulate peat decomposition. Recent studies stress the importance of plant species for peat quality and soil microbial activity. Thus, learning about specific plant-microbe-soil relations and their potential feedbacks for C and nutrient cycling are important for a correct understanding of C sequestration in peatlands and its potential shift associated with vegetation change. We studied how the long-term presence of blueberry and cotton-grass, the main vascular dominants of spruce swamp forests, is reflected in the peat characteristics, soil microbial biomass and activities, and the possible implications of their spread for nutrient cycling and C storage in these systems. We showed that the potential effect of vascular plants on ecosystem functioning is species specific and need not necessarily result in increased organic matter decomposition. Although the presence of blueberry enhanced phosphorus availability, soil microbial biomass and the activities of C-acquiring enzymes, cotton-grass strongly depleted phosphorus and nitrogen from the peat. The harsh conditions and prevailing anoxia retarded the decomposition of cotton-grass litter and caused no significant enhancement in microbial biomass and exoenzymatic activity. Therefore, the spread of blueberry in peatlands may stimulate organic matter decomposition and negatively affect the C sequestration process, whereas the potential spread of cotton-grass would not likely change the functioning of peatlands as C sinks.
  • Tóth, Zsolt; Szlavecz, Katalin; Epp Schmidt, Dietrich J.; Hornung, Erzsébet; Setälä, Heikki; Yesilonis, Ian D.; Kotze, D. Johan; Dombos, Miklós; Pouyat, Richard; Mishra, Saket; Cilliers, Sarel; Yarwood, Stephanie; Csuzdi, Csaba (2020)
    In urban landscapes, humans are the most significant factor determining belowground diversity, including earthworms. Within the framework of the Global Urban Soil Ecology and Education Network (GLUSEEN), a multi-city comparison was carried out to assess the effects of soil disturbance on earthworms. In each of five cities (Baltimore, USA; Budapest, Hungary; Helsinki and Lahti, Finland; Potchefstroom, South Africa), covering four climatic and biogeographical regions, four habitat types (ruderal, turf/lawn, remnant and reference) were sampled. The survey resulted in 19 species belonging to 9 genera and 4 families. The highest total species richness was recorded in Baltimore (16), while Budapest and the Finnish cities had relatively low (5–6) species numbers. Remnant forests and lawns supported the highest earthworm biomass. Soil properties (i.e. pH and organic matter content) explained neither earthworm community composition nor abundance. Evaluating all cities together, earthworm communities were significantly structured by habitat type. Communities in the two adjacent cities, Helsinki and Lahti were very similar, but Budapest clearly separated from the Finnish cities. Earthworm community structure in Baltimore overlapped with that of the other cities. Despite differences in climate, soils and biogeography among the cities, earthworm communities were highly similar within the urban habitat types. This indicates that human-mediated dispersal is an important factor shaping the urban fauna, both at local and regional scales.
  • Meyer, N.; Welp, G.; Amelung, W. (2019)
    Knowledge about spatial patterns of soil respiration (SR) and its temperature sensitivity (Q10) is of emerging relevance for assessing carbon fluxes across the landscape. Related experiments are often conducted under controlled laboratory conditions and usually rely on soil samples, which are sieved and stored. Here, we investigated the effect of sieving and storage on SR and Q10. We took 14 samples from different land use types and soil textures. Samples were sieved to 2 mm at field-moist conditions and split into four treatments: sieved/no-storage, sieved/freeze-storage (−18  °C), sieved/cold-storage (+ 4 °C), and sieved/dry-storage (+ 40 °C). The storage time was 7 weeks. Intact soil cores were used as a control. The SR was not significantly affected by sieving/no-storage, sieving/freeze-storage, and sieving/cold-storage compared with the control. Yet, sieving/dry-storage significantly increased SR but all samples were similarly affected (r = 0.81 for the correlation between SR after sieving/dry-storage and SR in the control). The Q10 of sieving/no-storage (1.94 ± 0.28), sieving/freeze-storage (1.94 ± 0.23), sieving/cold-storage (2.37 ± 0.29), and sieving/dry-storage (2.29 ± 1.35) did not differ significantly from the control (2.12 ± 0.23). All samples responded similar to sieving and storage (r = 0.68–0.73 for the correlation between Q10 in each respective treatment and Q10 in the control), with the exception of sieved/dry-storage (r = 0.09). We conclude that sieving at field-moist conditions and subsequent freeze- or cold-storage is acceptable to derive SR and Q10 for the here reported storage time. Although dry-storage may be acceptable for the comparison of SR between samples, it should be avoided for realistic estimates of SR and for the determination of Q10.
  • Manninen, Noora Johanna; Soinne, Helena Susanna; Lemola, Riitta; Hoikkala, Laura Kristiina; Turtola, Eila (2018)
    Dissolved organic carbon (DOC) load in discharges from cultivated soils may have negative impacts on surface waters. The magnitude of the load may vary according to soil properties or agricultural management practices. This study quantifies the DOC load of cultivated mineral soils and investigates whether the load is affected by agricultural practices. Discharge volumes and concentrations of DOC and dissolved organic nitrogen (DON) were continually measured at three sites from surface runoff and artificial subsurface drainage or from combined total discharge over a two-year period (2012-2014). Two experimental sites in South-West Finland had clayey soils (with soil carbon contents of 2.7-5.9% in the topmost soil layer), and the third site in West-Central Finland had sandy soil (soil carbon contents of 4.3-6.2%). Permanent grassland, organic manure application, mineral fertilization, and conventional ploughing or no-till activities were studied. Furthermore, the biodegradable DOC pool of surface runoff and subsurface drainage water from no-till and ploughed fields was estimated in a 2-month incubation experiment with natural bacterial communities collected from the Baltic Sea seawater. The annual DOC and DON loads were affected by discharge volume and seasonal weather conditions. The loads varied between 25-52 kg ha(-1) and 0.8-3.2 kg ha(-1), respectively, and were comparable to those from boreal forests with similar soil types. The DOC load increased with increasing topsoil carbon content at all sites. There were slightly higher DOC concentrations and DOC load from permanent grassland, but otherwise we could not distinguish any clear management-induced differences in the total DOC loads. While only 6-17% of the DOC in discharge water was biologically degraded during the 2-month incubation, the proportion of biodegradable (labile) DOC in surface runoff appeared to increase when soil was ploughed compared to no-till. (c) 2017 Elsevier B.V. All rights reserved.
  • Meyer, Nele; Xu, Yi; Karjalainen, Katri; Adamczyk, Sylwia; Biasi, Christina; van Delden, Lona; Martin, Angela; Mganga, Kevin Z; Myller, Kristiina; Sietiö, Outi-Maaria; Suominen, Otso; Karhu, Kristiina (2022)
    Mountain birch forests (Betula pubescens Ehrh. ssp. czerepanovii) at the subarctic treeline not only benefit from global warming, but are also increasingly affected by caterpillar outbreaks from foliage-feeding geometrid moths. Both of these factors have unknown consequences on soil organic carbon (SOC) stocks and biogeochemical cycles. We measured SOC stocks down to the bedrock under living trees and under two stages of dead trees (12 and 55 years since moth outbreak) and treeless tundra in northern Finland. We also measured in-situ soil respiration, potential SOC decomposability, biological (enzyme activities and microbial biomass), and chemical (N, mineral N, and pH) soil properties. SOC stocks were significantly higher under living trees (4.1 +/- 2.1 kg m(2)) than in the treeless tundra (2.4 +/- 0.6 kg m(2)), and remained at an elevated level even 12 (3.7 +/- 1.7 kg m(2)) and 55 years (4.9 +/- 3.0 kg m(2)) after tree death. Effects of tree status on SOC stocks decreased with increasing distance from the tree and with increasing depth, that is, a significant effect of tree status was found in the organic layer, but not in mineral soil. Soil under living trees was characterized by higher mineral N contents, microbial biomass, microbial activity, and soil respiration compared with the treeless tundra; soils under dead trees were intermediate between these two. The results suggest accelerated organic matter turnover under living trees but a positive net effect on SOC stocks. Slowed organic matter turnover and continuous supply of deadwood may explain why SOC stocks remained elevated under dead trees, despite the heavy decrease in aboveground C stocks. We conclude that the increased occurrence of moth damage with climate change would have minor effects on SOC stocks, but ultimately decrease ecosystem C stocks (49% within 55 years in this area), if the mountain birch forests will not be able to recover from the outbreaks.
  • Graessler, Peter; Meyer, Nele; Peukert, Juergen; Welp, Gerhard; Damerow, Lutz; Lammers, Peter Schulze; Amelung, Wulf (2019)
    Hot vegetable oil can be used for weed control as an alternative to the use of herbicides. We analysed the temporal development of vegetable oil mineralization in soil and tested the role of nutrient supply on oil mineralization. Further, we investigated the effect of oil application on mineralization of native soil organic carbon (SOC), i.e. the priming effect. In a laboratory experiment, three oil dosages (0.1, 1.0 and 3.0ml per 35g soil) were applied to three arable soils and soil respiration was measured hourly. Both a C3-sunflower oil and a C4-corn oil were used in order to differentiate oil-derived CO2 from SOC-derived CO2. The results revealed that after 42days of incubation, 9.6 to 39.7% of the applied oil was mineralized which, however, also primed the mineralization of SOC by a factor of 2.2 to 4.2. The higher the applied oil amount, the lower was the percentage of oil-C mineralization, but the higher was the priming effect. The addition of fertilizer (0.29mgNg(-1) soil and 0.048mgPg(-1) soil) increased oil-C mineralization to 39.9 to 50.9%. We conclude that oil can temporarily accumulate in soil, especially in case of low nutrient supply. As the addition of oil stimulates SOC mineralization, a decrease of native SOC stocks may occur, which needs further quantification in long-term field experiments.
  • Marques, Maria Jose; Schwilch, Gudrun; Lauterburg, Nina; Crittenden, Stephen; Tesfai, Mehreteab; Stolte, Jannes; Zdruli, Pandi; Zucca, Claudio; Petursdottir, Thorunn; Evelpidou, Niki; Karkani, Anna; AsliYilmazgil, Yasemen; Panagopoulos, Thomas; Yirdaw, Eshetu; Kanninen, Markku; Luis Rubio, Jose; Schmiedel, Ute; Doko, Adrian (2016)
  • Chen, Zhijie; Setala, Heikki; Geng, Shicong; Han, Shijie; Wang, Shuqi; Dai, Guanhua; Zhang, Junhui (2017)
    Purpose Anthropogenic-induced greenhouse gas (GHG) emission rates derived from the soil are influenced by long-term nitrogen (N) deposition and N fertilization. However, our understanding of the interplay between increased N load and GHG emissions among soil aggregates is incomplete. Materials and methods Here, we conducted an incubation experiment to explore the effects of soil aggregate size and N addition on GHG emissions. The soil aggregate samples (0-10 cm) were collected from two 6-year N addition experiment sites with different vegetation types (mixed Korean pine forest vs. broad-leaved forest) in Northeast China. Carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) production were quantified from the soil samples in the laboratory using gas chromatography with 24-h intervals during the incubation (at 20 degrees C for 168 h with 80 % field water capacity). Results and discussion The results showed that the GHG emission/uptake rates were significantly higher in the micro-aggregates than in the macro-aggregates due to the higher concentration of soil bio-chemical properties (DOC, MBC, NO3-, NH4+, SOC and TN) in smaller aggregates. For the N addition treatments, the emission/uptake rates of GHG decreased after N addition across aggregate sizes especially in mixed Korean pine forest where CO2 emission was decreased about 30 %. Similar patterns in GHG emission/uptake rates expressed by per soil organic matter basis were observed in response to N addition treatments, indicating that N addition might decrease the decomposability of SOM in mixed Korean pine forest. The global warming potential (GWP) which was mainly contributed by CO2 emission (>98 %) decreased in mixed Korean pine forest after N addition but no changes in broad-leaved forest. Conclusions These findings suggest that soil aggregate size is an important factor controlling GHG emissions through mediating the content of substrate resources in temperate forest ecosystems. The inhibitory effect of N addition on the GHG emission/uptake rates depends on the forest type.
  • Lappalainen, Mari; Kukkonen, Jussi V. K.; Piirainen, Sirpa; Sarjala, Tytti; Setälä, Heikki; Koivusalo, Harri; Finer, Leena; Lauren, Ari (2013)
  • Karhu, Kristiina; Kalu, Subin; Seppänen, Aino; Kitzler, Barbara; Virtanen, Eetu (2021)
    Addition of biochar to soil has been shown to reduce nitrogen (N) leaching in pot experiments, but direct field measurements are scarce, and data is lacking especially from colder, boreal conditions. We studied the effect of soil organic amendments on nitrate (NO3-) and ammonium (NH4+) leaching using the resin bag method, by placing the bags containing ion-exchange resins under the plough layer. We compared N leaching under five different treatments at the Päästösäästö project site (Soilfood Oy) in Parainen, south-western Finland: non-fertilized control, fertilized control, and three different organic amendments: spruce biochar, willow biochar and nutrient fiber. During the 2017 growing season, resin bags were changed monthly between the end of May and beginning of September, extracted with 1 M NaCl, and analyzed for inorganic N. The daily leaching rate of NO3- was greatest at the beginning of the growing season, right after fertilization. Ammonium leaching was generally lower, and independent of the time since fertilization. The spruce biochar reduced cumulative NO3- leaching by 68% compared to the fertilized control. The NH4+leaching in the organic amendment treatments did not statistically significantly differ from the fertilized control in pairwise comparisons. In October 2017, after harvesting, the resin bags were placed under soil columns again, and left in the soil over winter to accumulate N leached during the plant-free period. Cumulative NO3- leaching during winter was consistent with the corresponding summer results, and average leaching decreased in the order: willow biochar >fertilized control >nutrient fiber >non-fertilized control >spruce biochar. Thus, we show here, for the first time in a field study from boreal conditions that spruce biochar soil application decreased nitrate leaching, while increasing its retention in the surface layer of the biochar-amended soil.
  • Zhu, Xudan; Zhu, Tingting; Pumpanen, Jukka; Palviainen, Marjo; Zhou, Xuan; Kulmala, Liisa; Bruckman, Viktor; Köster, Egle; Köster, Kajar; Aaltonen, Heidi; Makita, Naoki; Wang, Yixiang; Berninger, Frank (2020)
    Key message During the first summer, wood biochar amendments increased soil temperature, pH, and soil CO(2)effluxes in a xeric boreal Scots pine forest. The increase of soil CO(2)efflux could be largely explained by increases in by soil temperature. Higher biochar application rates (1.0 vs 0.5 kg m(-2)) led to higher soil CO(2)efflux while the pyrolysis temperature of biochar (500 or 650 degrees C) had no effect on soil CO(2)efflux. Context Using biochar as a soil amendment has been proposed to increase the carbon sequestration in soils. However, a more rapid soil organic matter turnover after biochar application might reduce the effectiveness of biochar applications for carbon sequestration. By raising the pyrolysis temperature, biochar with lower contents of labile carbohydrates can be produced. Aims To better understand the effects of biochar on boreal forest soil, we applied two spruce biochar with different pyrolysis temperatures (500 degrees C and 650 degrees C) at amounts of 1.0 and 0.5 kg m(-2)in a young xeric Scots pine forest in southern Finland. Methods Soil CO2, microbial biomass, and physiochemical properties were measured to track changes after biochar application during the first summer. Results Soil CO(2)increased 14.3% in 1.0 kg m(-2)treatments and 4.6% in 0.5 kg m(-2). Soil temperature and pH were obviously higher in the 1.0 kg m(-2)treatments. Differences in soil CO(2)among treatments disappear after correcting by soil temperature and soil moisture. Conclusion Biochar increased soil CO(2)mainly by raising soil temperature in the short term. Higher biochar application rates led to higher soil CO(2)effluxes. The increase in soil CO(2)efflux may be transient. More studies are needed to get the optimum biochar amount for carbon sequestration in boreal forest.
  • Soinne, Helena; Keskinen, Riikka; Räty, Mari; Kanerva, Sanna; Turtola, Eila; Kaseva, Janne; Nuutinen, Visa; Simojoki, Asko; Salo, Tapio (2021)
    To achieve appropriate yield levels, inherent nitrogen (N) supply and biological N fixation are often complemented by fertilization. To avoid economic losses and negative environmental impacts due to over-application of N fertilizer, estimation of the inherent N supply is critical. We aimed to identify the roles of soil texture and organic matter in N mineralization and yield levels attained in cereal cultivation with or without N fertilization in boreal mineral soils. First, the net N mineralization and soil respiration were measured by laboratory incubation with soil samples varying in clay and organic carbon (C) contents. Secondly, to estimate the inherent soil N supply under field conditions, both unfertilized and fertilized cereal yields were measured in fields on clay soils (clay 30-78%) and coarse-textured soils (clay 0-28%). In clay soils (C 2.5-9.0%), both the net N mineralization and the cereal yields (without and with fertilization) decreased with increasing clay/C ratio. Moreover, in soils with high clay/C ratio, the agronomic N use efficiency (additional yield per kg of fertilizer N) varied considerably, indicating the presence of growth limitations other than N. In coarse-textured soils, the yield increase attained by fertilization increased with increasing organic C. Our results indicate that for clay soils in a cool and humid climate, the higher the clay content, the more organic C is needed to produce reasonable yields and to ensure efficient use of added nutrients without high N losses to the environment. For coarse soils having a rather high mean organic C of 2.3%, the organic C appeared to improve agronomic N use efficiency. For farmers, simple indicators such as the clay/C ratio or the use of non-N-fertilized control plots may be useful for site-specific adjustment of the rates of N fertilization. Highlights We aimed to identify simple indicators of inherent soil N supply applicable at the farm level. In clay soils, the net N mineralization was found to correlate negatively with the clay/C ratio. In coarse-textured soils, agronomic N use efficiency improved with increasing soil organic C. Clay soils with high clay/C ratio are at risk of low yield levels.
  • Li, Jichen; Hernandez-Ramirez, Guillermo; Kiani, Mina; Quideau, Sylvie; Smith, Elwin G.; Janzen, Henry; Larney, Francis J.; Puurveen, Dick (2018)
    Soil organic matter (SOM) is a major driver of key agroecosystem functions. Our objective was to examine the dynamics of organic matter in whole soil, particulate (POM; > 53 mu m size), and mineral-associated (MAOM) fractions under varying crop rotations and nutrient managements at two long-term experimental sites (Breton and Lethbridge). Soil samples were collected from simple (2 yr) and complex (5 or 6 yr) crop rotations at the 5 - 10 cm depth. We found associations between SOM pools versus microbial community and soil aggregation. Compared to cropped soils, an adjacent forest exhibited a significantly higher soil total organic carbon (TOC) and a shift in SOM fractions with substantially higher POM. However, the forest soil had the lowest microbial biomass C among all the assessed land use systems (P <0 .05), suggesting that other factors than the amount of labile SOM (i.e., POM-C) were controlling the microbial community. When contrasted to simple 2 yr rotations, the complex rotations including perennials and legumes significantly raised TOC and soil total nitrogen as well as the stable SOM fraction (i.e., MAOM-C and -N)consistently for both Breton and Lethbridge sites. Our findings highlight that varying land managements have profound feedbacks on soil quality as mediated by alterations in long-term SOM dynamics.
  • Aaltonen, Heidi; Palviainen, Marjo; Zhou, Xuan; Köster, Egle; Berninger, Frank; Pumpanen, Jukka; Köster, Kajar (2019)
    Climate warming in arctic/subarctic ecosystems will result in increased frequency of forest fires, elevated soil temperatures and thawing of permafrost, which have implications for soil organic matter (SOM) decomposition rates, the CO2 emissions and globally significant soil C stocks in this region. It is still unclear how decomposability and temperature sensitivity of SOM varies in different depths and different stages of succession following forest fire in permafrost regions and studies on long term effects of forest fires in these areas are lacking. To study this question, we took soil samples from 5, 10 and 30 cm depths from forest stands in Northwest Canada, underlain by permafrost, that were burnt by wildfire 3, 25 and over 100 years ago. We measured heterotrophic soil respiration at 1, 7, 13 and 19 °C. Fire had a significant effect on the active layer depth, and it increased the temperature sensitivity (Q10) of respiration in the surface (5 cm) and in the deepest soil layer (30 cm) in the 3-year-old area compared to the 25- and more than 100-year-old areas. Also the metabolic quotient (qCO2) of soil microbes was increased after fire. Though fires may facilitate the SOM decomposition by increasing active layer depth, they also decreased SOM quality, which may limit the rate of decomposition. After fire all of these changes reverted back to original levels with forest succession.