Faculty of Agriculture and Forestry


Recent Submissions

  • Ihanainen, Laura (Helsingin yliopisto, 2020)
    The aim of this study is to develop a sustainable food chain model based on previous studies and an empirical survey by using the abductive method. Through the empirical study, the actions and goals of a sustainable food chain regarding the corporate social responsibility (CSR) of the food and grocery industries and consumers’ food choices are identified. The expectations and motives associated with a sustainable food chain are also determined. The corporate responsibility reports for the years of 2015-2018 are used as secondary empirical data. Consumers’ sustainable food choices and the image of CSR actions are studied through focus group interviews. The targets of the focus groups are students, mothers, and seniors. In the focus group interviews, consumers’ sustainable food choices, perspectives, and expectations of CSR in the food business are studied. The added value of the work is to bring new dialogue to the research of the sustainable food choices of consumers and companies' arguments for sustainability. The dialogue compares corporations’ sustainability actions and goals to consumers’ sustainable food choices and expectations of CSR. For consumers, the factors that influence the formation of a corporate image of sustainability are also examined. The sustainable food chain model created in this study brings a new, holistic perspective to the theoretical debate by questioning the linear food chain model and combining dimensions of the circular economy and the whole food chain and its sustainability. The sustainable food chain model is based on the circular economy because previous studies underline that current food production and consumption habits are unsustainable and a transition from the linear food chain model to the circular economy is needed. Key findings of the empirical study are the following. 1) Sustainability actions and goals in the grocery and food industries are focused on environmental sustainability and are motivated by economic profitability and competitiveness. 2) Plant-based and domestic products are highlighted in consumers’ sustainable food choices and are motivated by health and safety. 3) Consumers’ image of the sustainability of a corporation is made up of factors that consumers consider when making sustainable choices, such as organic, local food, and plant-based options, as well as environmentally friendly packaging. 4) Consumers’ image of the sustainability of and familiarity with a company go hand in hand. The more familiar the company is to a consumer, the more reliable it is considered. When a company’s and a costumer’s values meet, the consumer thinks that the company is more trustworthy. Consumers are also more likely to make purchases from that company.
  • Juvonen, Minna (Helsingin yliopisto, 2020)
    Oligosaccharides potentially present in cereal matrices have attracted attention because of their health-related properties, such as prebiotic potential. In addition to those that are naturally present, oligosaccharides can be formed during processing by the hydrolysis of cereal polysaccharides, such as arabinoxylan, by endogenous or microbial enzymes. In sourdough fermentation, additional poly- and oligosaccharides may be produced by lactic acid bacteria (LAB). In the work performed for this thesis, mass spectrometry (MS) methods were implemented in the structural analysis of various enzymatically produced oligosaccharides. The research was focused on finding solutions to separating and identifying oligosaccharide isomers. To determine the linkage positions of linear mixed-linked glucooligosaccharides (GLOS), the feasibility of the positive and negative electrospray ionisation multiple-stage MS (ESI-ITMSn) were compared. Next, the ability of ESI-ITMSn to detect the branching points and linkage positions of complex arabinoxylan-oligosaccharides (A)XOS was studied. The MS method was also coupled to hydrophilic interaction liquid chromatography (HILIC) to separate and identify the (A)XOS in mixtures. Finally, the potential of travelling wave ion mobility spectrometry (TWIMS) combined with MS to differentiate the isomeric (A)XOS was evaluated. To study the structures of the isomeric acceptor products formed by dextransucrase from LAB, 13C-labelling was applied with ESI-ITMSn. The ESI-ITMSn method provided structural information about the molecular weights, sequences and linkage positions of the linear mixed-linked GLOS and (A)XOS. Negative ionisation was found to be more informative than the positive ionisation mode in analysing the linkage positions. The stepwise C-ion fragmentation in negative mode from the reducing end towards the non-reducing end allowed to study the linkage diagnostic fragment ions from the middle and the non-reducing end in both linear and branched oligosaccharides. O-2 or/and O-3 arabinofuranosyl substituents of AXOS were determined by the presence or absence of diagnostic ions in the ESI-ITMS3 analysis in the negative mode. The ESI-ITMSn method, combined with 13C-isotope labelling, enabled the analysis of unique trisaccharides produced by dextransucrase as well as the further detailed analysis of the isomeric fragment ions. Coupling tandem mass spectrometry (MS/MS) to HILIC enabled the separation and identification of all AXOS by the combination of retention times and the MS/MS spectra. CID-TWIMS-MS/MS was shown to be a powerful tool in differentiating the isomeric AXOS when both the fragment ions and the precursor ions were analysed.
  • Wang, Yaqin (Helsingin yliopisto, 2020)
    Utilization of grain legumes (such as faba bean) and minor cereals (such as sorghum and millet) is constantly growing since consumers are increasingly interested in sustainable, plant based and health promoting foods. Grain legumes and minor cereals are raw materials with high nutritional quality due to high content of protein, dietary fibre and other bioactive compounds. Utilization of these grains is challenging as they have negative impact on product texture and flavour. Sourdough technology is one of the “clean label” options to improve technological functionality of these grains. The aim of this thesis was to study the influence of faba bean, sorghum and millet on technological and nutritional properties of composite wheat bread. Wheat flour was replaced with faba bean (30%), sorghum or millet flours (50%), which were either native or fermented. Utilization of native flours had detrimental effect on the rheological properties of dough as well as the volume, texture and sensory properties of bread in comparison to 100% wheat control breads. In contrast, mildly acidified and dextran-containing flours improved all properties of composite breads. The functionality of sourdough was based on sufficient production of dextran and mild acidification. Faba bean sourdough fermented with Weissella confusa VTT E-143403 (dextran content of 5.2% dry weight) improved the specific volume (21%) and texture of breads, especially softness (12%). However, faba bean sourdough fermented with Leuconostoc pseudomesenteroides DSM 20193 (dextran content of 3.6% d.w.) decreased bread volume and increased crumb hardness, probably due to the higher acidification. Furthermore, efficacy to improve shelf-life (delay staling rate) was shown to be linked to slower starch retrogradation and improved water retention. Sourdough fermentation also increased the level of free phenolic compounds in millet and sorghum. Fermentation of millet decreased starch in vitro digestibility (lower predicted glycemic index), while improving the in vitro digestibility of proteins. These changes may be attributed to the production of organic acids and concomitant activation of hydrolytic enzymes like glycoside hydrolase, cellulases, esterases and proteases. Utilization of tailored sourdough technology had a significant impact on the sensory properties of sorghum breads. Sourdough fermentation of sorghum without dextran increased unpleasant flavour properties such as acidic, bitter flavour and aftertaste, probably due to increased content of acids and small molecular weight polyphenols (e.g. caffeic acid). This study showed that dextran containing sorghum breads had less intensive acidic and bitter flavour and milder aftertaste even though the actual acidity and polyphenol compositions was the same as in control breads. This revealed the exceptional ability of dextran to mask acidic and bitter flavour notes. This observation was further verified by adding purified dextran (0.12−0.96% bread weight) to white wheat bread together with acid and bitter flavour compounds (lactic/acetic acid and caffeine). When the amount of dextran was sufficient (> 0.43% b.w.), the perceived intensity of acidic and bitter flavours in the bread decreased. This thesis demonstrated efficient production of dextran in situ in faba bean, sorghum and millet flours during sourdough fermentation, which facilitates production of nutritionally high quality composite breads without additives. Additionally, this thesis revealed for the first time the ability of dextran to modify sensation of acidic and bitter flavours, which allows future product innovations in plant based foods.
  • Hassan, Badal Ahmed (Helsingin yliopisto, 2020)
    Dryland ecosystems support the livelihood of millions of people in the Horn of Africa. However, these ecosystems have been exploited and affected by continuous overgrazing, fire and tree cutting. The general aim of the study was to find ways of improving the adaptive strategy and livelihood of the rural communities, and promoting ecosystem sustainability in the Horn of Africa, using Kenya and Somalia as specific case studies. The theoretical framework of the study was based on the conceptual framework for sustainable development or sustainability. The study examined the non-wood forest products (NWFPs), both for food and non-food commodities, harvested to overcome food insecurity. It paid particular attention to the role of the aromatic resin bearing species of Boswellia and Commiphora in poverty alleviation and climate change adaptation in the region. It also examined the rural communities’ views on the causes, effects and socio-economic impacts of resource degradation. Socio-economic field surveys were conducted in Wajir district of north-eastern Kenya and three districts in Somalia, Addado, Buhodle and Galka’ayo. A systematic literature review was also employed to identify, select and critically review the current information on socio-economic contributions of aromatic resins in the Horn of Africa. Qualitative analyses from surveys, group discussions and key informant consultations were used in processing the data. The research identified several woody species which provide both food and nonfood products. The results emphasised the potential for using Boswellia and Commiphora species as agroforestry trees, for not only improving the economic conditions of the farmers, but also for increasing land productivity. The study highlighted forest degradation, droughts, building of reservoir and over-grazing as the main factors causing land degradation in the study areas. Farmers’ adoption of new agroforestry management techniques in general, and those for Boswellia and Commiphora species in particular has a distinct role in biodiversity conservation and climate change adaptation in the Horn of Africa. This would also enhance ecosystem sustainability and improve rural livelihood security and thereby facilitate poverty alleviation. Keywords: Acacia-Commiphora woodlands, agro-pastoralists, non-wood forest products, frankincense, myrrh, Horn of Africa, Somalia, Kenya.
  • Rehan, Sheikh Feroze (Helsingin yliopisto, 2020)
    The objectives of this thesis were to make a systematic and detailed analysis of the diversification of farm households in Bangladesh. The thesis, based on three articles, applied data from a survey of 260 farm households in the central, northern, and southwest regions of Bangladesh. The first, second and third papers highlighted on-farm diversification, income diversification and the relationship between farm and food consumption diversification respectively. The first article identified the factors influencing on-farm diversification and, in doing the analysis, the paper compares farm households highly specialized in rice cultivation with more diversified farm households. Results revealed that the age of the head of the household, technical assistance, farm size, access to markets, access to credit and regional dummies are the main determinants of on-farm diversification. The active participation of women in farming activities was a noteworthy determinant that was found to increase diversification in Bangladesh. The second article investigated the determinants and purpose of income diversification in Bangladesh. The findings showed that the extent of the overall diversification was determined by household endowments of assets such as wealth, higher education, easy access to market, more earners, better infrastructure, and its purpose was accumulation of wealth. However, farm households are involuntarily pushed into off-farm wage diversification for survival, and off-farm self-employment diversification is chosen as an accumulation strategy to capture higher return opportunities. This study pointed out that diversification is linked to agriculture rather than being a condition of departing from it. Article 3 linked the research gap through presenting empirical evidence on the effect of diversification on household food security in the Bangladeshi context. The study found that diversification positively influences food security, especially from the food consumption diversity viewpoint. Importantly, this suggests that special focus is required on diversified multiple crop and non-crop production and moving out of pure rice cultivation. Moreover, formulating policies that emphasize investment in infrastructure, electrification, and education to facilitate diversification and enhance household food security has been recommended.
  • Miettinen, Jenni (Helsingin yliopisto, 2020)
    This dissertation develops a framework to examine socially optimal forest management when nutrient and sediment loads from forestry are considered as a negative externality. The Faustmann rotation model is extended to include the runoff function to describe the water quality impacts of nutrient and sediment loads from forestry. This thesis consists of an introductory section and four articles that analyze the different forest management practices and associated water protection. Examined practices include final harvesting in both mineral soils and peatlands, stem-only harvesting and whole-tree harvesting in peatlands, and ditch network maintenance. The water protection measures included are buffer zones in mineral soil forestry and overland flow fields and sedimentation ponds in drained peatlands. The main contribution of this thesis is the developed framework for analyzing socially optimal forest management when water quality is taken into account. The analysis shows that the nutrient and sediment load damages associated with forest management depends highly on management practices. The nitrogen load caused by final harvesting in mineral soils results in relatively low nitrogen load damages. In contrast, the sediment load damages due to ditch network maintenance in the sensitive headwater catchment are very high. Furthermore, the cost-effectiveness of water protection measures differs significantly. From society´s viewpoint, the buffer zones used in mineral soil forest management are not a cost-effective water protection measure but when biodiversity benefits are taken into account, in addition to water quality, they become socially desirable. Overland flow fields are very cost-effective water protection measures for peatland forestry. Finally, the water protection costs in forestry and agriculture are compared in a river basin model. A cost-effective solution requires the highest nutrient reductions in agriculture, though it also implements water protection measures, especially in drained peatland forestry.
  • Lötjönen, Sanna (Helsingin yliopisto, 2020)
    This thesis studies the design of socially optimal policies for climate mitigation and water protection for two agricultural production lines: crop and dairy production. It provides analytical insights into optimal management, both in the absence and presence of nutrient runoff and greenhouse gas emissions, and develops policies to incentivize private production when externalities to water and atmosphere exist. Special attention is devoted to the coeffects of agricultural water protection measures on climate mitigation and of climate mitigation measures on water protection and their implications for marginal abatement costs and optimal policies. The thesis studies crop rotations with legumes and dairy production in detail. It additionally derives cost functions for reducing emissions by combining individual measures, such as fertilization, buffer strips, catch crops, tillage methods, afforestation and green fallow. In general, Pigouvian taxes on greenhouse gas emissions or on diffuse nutrient loading as first-best policies are not possible due to problems in measuring nonpoint source loading. Therefore, second-best policies, such as uniform taxes levied on animal numbers or fertilization or subsidies based on buffer strip width or transporting manure, are developed and applied numerically. Based on the findings, in comparison to the first-best policies, the second-best policies are relatively effective in producing the desired policy goals. Study I of the thesis shows how legumes in crop rotations outperform cereal monocultures economically and environmentally in many cases, provided there is adequate demand for legumes, and develops differentiated nitrogen tax and buffer strip subsidies based on the cultivated crop. Study II focuses on the use of nitrogen, land use, dairy cow diet and climate emissions within dairy production. This study demonstrates the overall spatial pattern of manure application and illustrates the main measures to reduce greenhouse gas emissions and nutrient runoff. Uniform nutrient taxes are found functional, although spatially differentiated taxes produce higher welfare. Study III highlights the importance of accounting for multiple pollutants and their coeffects when designing environmental policies and calculating marginal abatement costs. In the case of cobenefits, the optimal tax on the focus pollutant is relatively higher, increasing abatement and the supply of cobenefits.
  • Pilli-Sihvola, Karoliina (Helsingin yliopisto, 2020)
    This thesis consists of an introduction and four articles which analyse disaster risk management (DRM), including disaster risk reduction (DRR), disaster management and climate change adaptation (CCA) from economic and policy perspectives. The main research question is: what are the means to overcome the salient challenges in DRM and CCA policies and measures which have been designed to reduce the risks posed by extreme weather under uncertainty? Theoretically, it advances the policy level development of DRM and CCA integration and provides a mathematical definition for over-adaptation to climate change. Empirically, it analyses integrated DRM and CCA policies and measures, and analyses challenges related to their development and implementation. Article I provides a formal definition for DRR and CCA policy integration at horizontal (inter-ministerial) and vertical (intra-ministerial) dimensions to assess DRR and CCA policy-making and analyses policies and their integration challenges in Zambia. The theoretical contribution to the literature is the formal definition for DRR and CCA policy integration and the empirical contribution is provided by evidence of potential challenges created by the governance system. Article II discusses the contribution of the underlying vulnerability drivers of governance, societal and political factors, culture, policies and their implementation, and argues that vulnerability reduction is a key aspect in reducing disaster and climate change risk. The theoretical contribution furthers the discussion on new dimensions in climate change risk analyses by emphasising the potential impacts of societal development, such as social trends and social cohesion, in effective DRM and CCA. The article contributes to the empirical literature by assessing Nordic welfare state structures as a means to reduce disaster risk and climate change. Article III analyses the costs and benefits of a major integrated DRM and CCA policy in Finland, and describes how over-adaptation, i.e. over-investment in DRM and CCA may affect the legitimacy of a policy aiming partially at reducing extreme weather risk. The article contributes to the theoretical literature by providing a mathematical definition for over-adaptation and to the empirical literature through the case study. Article IV assesses the effects of a potential innovation in weather service provision to improve CCA and safety in the road transport sector. The article identifies and describes the main trends and potential innovations in the provision and use of weather services. It contributes to the empirical literature on CCA and weather service benefit valuation.
  • Korhonen, Janne (Helsingin yliopisto, 2020)
    Nitrogen (N) and associated carbon (C) cycling were studied in an N-limited boreal Scots pine (Pinus sylvestris L.) forest in Hyytiälä, southern Finland and were compared to two N-rich temperate forests, the Speulderbos Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) forest in the Netherlands and the Sorø European beech (Fagus sylvatica L.) forest in Denmark. Nitrogen and carbon cycling in the Scots pine forest were modelled. These results were compared to continuous year-round observations to obtain an overall understanding of nutrient cycling in the forest. The N balance of the Scots pine forest was calculated based on direct measurements, measurement-based estimations and model results. Nitrogen uptake and resorption by trees were estimated based on continuous measurements. Litter fall dynamics of the Scots pine and Douglas fir forest were compared. Scots pine needle N dynamics were compared between the three forests. Soil was the main N storage in the boreal Scots pine forest and most of this N was in recalcitrant form. Scots pine trees were very efficient at saving and recycling N. This together with atmospheric N deposition, potential N uptake by the canopy and organic N uptake mean that the importance of mineralization as the process driving N cycling may have been overestimated. Most of the N was allocated simply to replace dead tissue in the Scots pine forest. This means that the additional N received via N deposition may significantly increase the N pool size that trees have for extending their biomass N (net growth). Because Scots pine trees were found to be dependent on efficient N use and recycling, this adversely also means that even slight snow and storm damages may cause foliar biomass to decrease due to reduced relocation on top of the direct effect of losing the foliage due to damage, affecting forest carbon sink strength.
  • Kirjoranta, Satu (Helsingin yliopisto, 2020)
    The structure of a common cereal-based crispy snack product can be defined as solid foam. Consumption of such snack products has become popular especially among teenagers and young adults. At the same time obesity has become a common problem. Conventional snack products consist mainly of starch and fat and they have very low protein and dietary fiber content. It is known that dietary fiber and protein have many health effects and they can help in losing weight by avoiding the feeling of hunger. It is therefore important to develop products with high protein and fiber content which can be used instead of common low nutritional value snack products. The aims of this academic research were to utilize several fiber and protein sources in order to produce snack products using extrusion cooking technology which is a common way to produce foods. Special attention was paid to using by-products from the food industry and ingredients which are not commonly used in snacks. Snack products were prepared with extrusion cooking technology in several trials with various mixtures of ingredients. Studied ingredients were: whole grain barley flour, defatted whole grain and endosperm oat flour, corn flour, differently treated oat bran concentrate fractions (OBC), brewer´s spent grain from barley (BSG), polydextrose (PD), whey protein isolate (WPI), Peruvian pseudocereals (amaranth, quinoa, kañiwa), barley starch and waxy corn starch. Snack products were prepared by varying several extrusion parameters: water content of the mass, screw speed and temperature of section 6 and die. Effects of extrusion parameters on the process (torque, specific mechanical energy and pressure at the die) and on the properties (water content, expansion, hardness) of the snacks were studied using response surface methodology. Properties of the most expanded products were studied in more detail. Several fiber sources could be used in the production of snacks, but high fiber content made snacks hard and poorly expanded. However, expanded and crispy barley-based snacks with high fiber and protein content were obtained by adding starch or WPI. Extrusion cooking was also found to increase the extractability and viscosity of barley β-glucan. Furthermore, water-soluble OBC increased the expansion of extrudates made of defatted endosperm oat flour. Expanded, crispy gluten free snack products could be prepared using defatted oat endosperm flour with water-soluble OBC or corn flour enriched with Peruvian pseudocereals at content of 20% of solids. Even though ingredients had a great effect on the properties of the snacks, structure could be modified by extrusion variables: increasing screw speed and decreasing water content of the extruded mass increased expansion and decreased hardness of the snack products. This research gave information how fiber and protein rich ingredients for example by-products could be utilized in the production of healthy snacks made by extrusion cooking.
  • Wang, Linping (Helsingin yliopisto, 2020)
    Viral disease caused by co-infection of Sweet potato feathery mottle virus (SPFMV) and Sweet potato chlorotic stunt virus (SPCSV) is a severe problem that affects the production of sweetpotato (Ipomoea batatas) by reducing crop yields by up to 90%. RNase III encoded by SPCSV (CSR3) has been shown to be a viral suppressor of RNA silencing (VSR) with the ability to counteract the host’s antiviral RNA silencing defense by cleaving small interfering RNA (siRNA). This function of CSR3 is responsible for the synergistic interaction between SPCSV and other viruses including SPFMV. Thus, CSR3 may be an ideal drug target for the development of a new antiviral treatment. Yet, no inhibitor compounds have been developed, and no screening has been carried out. Thus, in this study, we sought to identify chemical inhibitors of CSR3 in order to diminish viral disease in sweetpotato. Inhibitor identification was initiated with virtual screening using computer-aided Glide docking. In total, 6,620 compounds of 136,353 were selected. Then a novel high-throughput screening (HTS) process based on fluorescence resonance energy transfer was carried out, taking into consideration the catalytic activity of CSR3 on siRNA. Of the 6,620 compounds, 109 potential inhibitors were selected according to their percentage of inhibition. Afterward, dose-response assays were performed using our HTS approach, followed by affinity binding assays between compounds and CSR3 using surface plasmon resonance and microscale thermophoresis. In addition, the compounds’ ability to affect viral accumulation in planta was verified using plants grown in a culture medium and in soil with RT-qPCR and imaging-based plant phenotype approach, respectively. As a result, four compounds were confirmed to improve the photosynthesis performance of plants grown in soil and reduce SPFMV accumulation in SPCSV and SPFMV co-infected sweetpotatoes. The study is the first to identify effective inhibitors for CSR3, opens a path toward the development of new strategies to fight viral diseases caused by the synergism of SPCSV.
  • Särkikangas, Ulla (Helsingin yliopisto, 2020)
    This doctoral study investigates heavy and long-term use of social welfare and healthcare services in the everyday life of special needs families. A special needs family is defined as a family that has at least one child who needs special support and services for her/his health, growth and/or development. Use of services is approached from the perspectives of everyday activities and time use. The study increases understanding of the variety of activities that the long-term service use requires from these families as well as the rhythmic changes in activities and time use that can be identified from the families’ everyday lives. The interpretative resources of this study draw from the traditions of service research and consumption and home economics studies. The study approaches long-term service use from the perspective of customer-dominant logic and customer activity which have roots in the service research tradition. The analysis of families’ everyday activities and time use draws from Lefebrian rhythmanalysis and especially from the understanding of the discordance of rhythms. This enables investigation of rhythms in time use as well as ruptures and discordances that are linked to them. The methodological approach of the study is based on the interpretative research tradition with an emphasis on the phenomenological perspective. The empirical data consist of ten interviews of parents with special needs children. The interpretation and reporting of the findings utilize both interpretative resources listed above and earlier studies on special needs children and families, for example in the fields of social-, health- and education studies. The findings of the study show that families can, in the course of the years, use as many as tens of services. Families’ extensive experience of service use includes early childhood education and teaching services in addition to social welfare and healthcare services. Apart from the activities that take place in the interaction between families and service producers (such as going to the doctor), the study also identified activities that are meaningful for the families but are not taken into account in the service provisioning or that are downright invisible to service providers. The daily management of fragmented services using different operating models requires, for example, diverse and multifaceted activities related to information search and time management. Problems or challenges associated with the service system lead to situations in which parents who try to receive and use services are forced to perform even such activities that normally should be conducted by a service provider. Furthermore, the findings demonstrate that services have not been digitized in accordance to the families’ expectations. The discordance of rhythms which allows us to interpret changes in families’ everyday activities and time use highlight situations in which the development of everyday rhythms is disturbed, in which there are tensions of conflicts between rhythms, and in which there are temporal pressures involved in activities. Service providers’ product-oriented operating models and timetables can, for example, fragment families’ everyday activities and cause multitasking pressures which then weaken the experience of harmony in everyday life. The findings of the study indicate that the everyday life of families who are heavy and long-term users of services contains activities that are associated with the service use but are invisible or not accounted for in the service provision. From the families’ perspective these activities can appear as conflicting: the services aim to support families’ everyday life and wellbeing, but their active use takes valuable and limited time away from other everyday activities. Families also seem to have problems with finding a rhythmic balance between the support and care of the special needs child and the allocation of time and activities required by the service system. These both factors may hinder the harmonious everyday life and families’ wellbeing.
  • König, Walter (Helsingin yliopisto, 2020)
    The objectives of this research were to investigate the ensilability of legume bi-crops and the effect of additives on silage fermentation quality. Silages were made in laboratory scale-silos, and their quality was assessed by qPCR quantification of clostridia DNA and fermentation pattern. Mixtures of white lupin (Lupinus albus) and spring wheat (Triticum aestivum) were ensiled unwilted at early and late maturity stages (publication I) and at late maturity stage both unwilted and wilted (publication II). A mixture of red clover (Trifolium pratense), timothy (Phleum pratense) and meadow fescue (Festuca pratensis) was wilted 21 and 45 hours before ensiling (publication III). The additive treatments were untreated control (CON), formic acid (FA, 4 L t-1 fresh matter), mixtures of sodium nitrite and hexamethylenetetramine (NaHe), and sodium nitrite alone (SN). Lactic acid bacteria (LAB, homofermentative) treatment was only used in I. Dry matter (DM) concentration of forage crops ranged from 199 to 314 g kg-1 DM. The ensiled bi-crops in I were low in nitrate (0.2 g kg-1 DM), while nitrate concentrations in II and III were 3.8 and 4.0 g kg-1 DM, respectively Control and FA treatments produced high butyric acid concentrations of silages in I, and lower or zero concentrations in II and III, whereas NaHe and SN exposed no or only traces of butyric acid. Lactic acid bacteria treatment was successful only with lupin-wheat mixtures having high WSC concentrations at early maturity stage (I). Control treatment exposed high ammonia-N values between 129 and 241 g kg-1 N in all investigated lupin-wheat mixtures (I and II). The number of clostridial DNA copies (spores, vegetative cells and dead cells/spores) was highest in the CON and FA treatments. All silages were aerobically stable (I-III). The effect of hexamine (hexamethylenetetramine) on silage quality was investigated at two DM concentrations of a lupine-wheat mixture (II). Hexamine addition did not improve silage quality. Increasing hexamine concentration in a sodium nitrite solution showed no effect on clostridial activity compared to sodium nitrite alone. Clostridia was detected only in a few FA replicate silos (II). The use of SN as a sole solution (900 g-1 t) or as a mixture with hexamine (NaHe) produced silages of better quality than the treatments with FA (4 L t-1). In conclusion, legume bi-crops are difficult to ensile due to low DM, high buffering capacity, low nitrate concentration and being prone to clostridial activity and butyric acid fermentation. Nitrite-based additives were more suitable than formic acid when ensiling legume bi-crops that are prone to clostridial contamination.
  • Ebrahimi, Nashmin (Helsingin yliopisto, 2020)
    Selenium (Se) is an essential element in the nutrition of humans and animals due to its core function in important enzymes and as a component of some proteins. Plants take up and metabolize Se in the same pathway as sulfur (S) because these elements have similar chemical and physical properties. At low dosage, Se is a beneficial element for the growth and development of plants, especially under stress conditions. However, its necessity for a plant’s life cycle has not been proved. Agronomic biofortification is a solution to increase daily nutrient intake in human through the application of mineral micronutrient fertilizers to increase their content in edible parts of crops. In agronomic biofortification via Se fertilizer, plants play an important role in providing the food chain with Se. As compared with inorganic Se, organic Se compounds in plants are less toxic even at higher concentration in human and animal tissues. Most plants accumulate selenomethionine (SeMet) and some Se-accumulators produce selenomethylselenocysteine (SeMSeCys) and its γ-glutamyl derivative. These nonprotein selenoamino acids have anticarcinogenic and antitumor properties in animals and humans. Therefore, the use of plants with high activity of homocysteine/selenocysteine methyl transferase (HMT/SMT) enzyme in biofortification to produce these organic Se compounds is desirable. In Finland, soils are naturally low in bioavailable Se, so some fertilizers have been amended since 1984 with selenate to counteract the negative impact of low Se intake on the health of humans and animals. The uptake, remobilization and loading of Se into seeds are strongly dependent on various factors such as soil properties, Se species and their content in the soil as well as plant species and climatic conditions. Moreover, the recovery of fertilizer Se is low (5-35%) and most applied Se probably remains in soils. The bottlenecks in Se biofortification pathways are not fully understood, so further studies are needed to investigate these bottlenecks and the fate of applied Se in the agroecosystem. The aims of the present study were to identify the bottlenecks in the Se biofortification pathway and to assess the potential of Se-enriched plant residues in soil as Se sources for plants. An additional aim was to investigate the assimilation pathways of Se and its speciation in a biofortified oilseed rape crop. Furthermore, other important crops (wheat and forage grasses) were studied to compare their efficiency (ratio of Se in harvested parts into its application) of Se fertilizer recovery and biofortification under field conditions. Results from a greenhouse experiment indicated that oilseed rape plants accumulated Se (18.7 µg g 1) in their leaves 6 h after soil application of selenate. As expected, 80% of the Se that accumulated in the leaves was in the form of selenate. At 14 days after treatment, the two most accumulated Se species in the leaves were selenate (64%) and SeMet (29%). Eventually, SeMet was the most accumulated Se species (54 - 96%) in the seeds and meal. Six hours after Se treatment only 4% of Se accumulated in the leaves was in the labile form of SeMSeCys. The homology of the amino acid sequences of the SMT enzyme in oilseed rape with B. oleracea and Astragalus, indicated its similarity with non-accumulator B. oleracea plants with dual HMT/SMT activity and this probably resulted in the transience of SeMSeCys accumulation. Further study on the application of various Se forms (selenate and Se-enriched plant residues) illustrated that Se-enriched plant residues in the
  • Kankaanpää, Tuomas (Helsingin yliopisto, 2020)
    Climate change is affecting species distributions and phenologies. These changes may in turn affect how species interact with each other. Thus, species-specific effects of a changing environment are expected to affect the whole food web. Due to this dynamic complexity, community and ecosystem level responses to climate change are still relatively poorly understood. In this thesis I use the Arctic ecosystem to fill in some of this knowledge gap. For this, the interaction webs of Arctic communities are ideal, as they are simple enough to sample adequately. At the same time, the Arctic has been warming twice as fast as the rest of the globe, likely accentuating the effects of climate change. In my thesis, I concentrate on a module of the total food web, the insect parasitoids, insect herbivores and a widespread flowering plant, Mountain Avens (Dryas). I specifically study how climatic factors affect each species in the community, whether species’ responses be predicted based on species traits such as parasitism strategy (koinobiontism versus idiobiontism), and whether different trophic levels respond in concert. To strengthen my conclusions as based on a purely observational study design, I approach these questions at different spatial and temporal scales. I examine local altitudinal gradients within a walking distance. I organize a similar sampling at a geographical scale, which includes latitudinal variation in climate as well as regions which have experienced different types of climate change. Finally, I contrast these spatial snapshots against a real time series at a single location. In the first chapter I asses both how plant and arthropod phenologies respond to climatic factors over time, but also how the landscape level patterns in snow conditions are changing. I found phenological sensitivities of arthropods to vary with their feeding guild, supporting the idea of climate change induced changes in phenological matching between interacting species. The spatial pattern in the relative timing of snowmelt was similar between the years, but with earliest melting areas showing the most variability. In the second chapter I study the local spatial occurrence patterns of parasitoid wasps and flies which use herbivorous butterflies and moths as their hosts. I also investigate the spatial patterns of specific type of herbivory, the florivory on Avens flowers by a specialist herbivore Sympistis zetterstedtii. Furthermore, I study the parasitism rates of parasitoids in the larvae of this particularly abundant moth. I find that warm and dry conditions increase both overall parasitoid occurrence and the levels of herbivory. Parasitoids however showed marked species-specific differences in their spatial occurrence patterns, some of which can be attributed to their species trait of parasitism strategy. Also, the manner in which parasitoid abundance translates into parasitism rate in Sympistis larvae was different between the two influential species. Systematically contrasting responses in the parasitoid community generate the potential for community change as climatic conditions change. In the third and final chapter of this thesis I study spatial patterns in the functional parasitoid community composition as determined by main host group and the influential trait of parasitism strategy. I find that geographical patterns in functional parasitoid communities were best explained not by of the large variation in long-term climatic mean conditions, but by the variation in the rate and mode of climate change during the past 18 years. Parasitoid communities in localities which have experienced more temperature rise during the summer period were characterized by a higher proportion of parasitoids using lepidopteran hosts, and a larger than expected proportion of these are idiobiont. Across a 20-year time series collected at Zackenberg, I find that host group abundances respond to climatic factors as would be expected if realized climate change really has influenced the community compositions of Pan-Arctic parasitoid communities. Taken together, my results show strong evidence for climatically driven community change. It also brings out that such community shifts may already have occurred in the rapidly changing Arctic, and that they have been accompanied by increases in reproductive losses by key plants to herbivory. This suggests that even isolated communities in pristine environments are susceptible to climate induced change.
  • Laaksoharju, Taina (Helsingin yliopisto, 2020)
    Nature contact has been acknowledged as beneficial for children’s development and wellbeing, as it is for all humans. At the same time, children’s free play in nature and independent mobility, ‘free-ranging,’ has been declining in Western societies in recent decades. One solution to this dilemma, nature clubs and camps with the aim of introducing and promoting children’s nature contact, are becoming increasingly common. Nature programmes aim to (re-)connect children and nature through educational goals. One example of such a place, the children's garden, is becoming increasingly recognized as a place where adults hope that children will learn various skills and subjects, while simultaneously hoping the children will improve their relationship with nature. Despite the known educational and health benefits of gardening, children's interactions with the actual physical elements of a place are less understood and examined. By recognizing more factors that affect children's process in forming a close, durable and meaningful relationship with natural places like the garden, adults become more capable of appropriately supporting children. The aim of this research was to unravel how children connect with such a natural space, the garden by looking at the place-specific affordances. The concept of affordances is the key to this study; it refers to the physical elements of the environment that reveal opportunities for interaction once they have been perceived. The research comprises two parts. The first phase of the study evaluated Finnish primary school children’s relationship with plants and nature, by comparing rural/suburban and boys’/girls’ attitudes and knowledge about plants and favourite places. The comparison was conducted through a survey of 76 children. Using mixed methods, the statistical analysis included paired cross tabulation, and chi-square-tests (χ2) to measure the significance of differences among the groups rural/suburban, and boys/girls. The second part of the study consisted of qualitative fieldwork with ethnographic participant and non-participant observations throughout summers 2008-2010 in the Kumpula School Garden in Helsinki. In order to study the phenomenon of how children make their connection to nature through place-based affordances, the study leans on an interpretivist ontology that views reality as understandable by observing actors within their social context. To assess the child-centred potential of a garden environment for building connection to nature, I examined the affordances in a garden camp context, focusing on 6- to 11-year-old, inexperienced children (~40 participants for each year of the study). The long-term fieldwork generated outstanding data: field reports and notes, videos, photographs and children’s drawings and interviews. Grounded theory method (GT) was applied in studies II and III. Analysis followed the GT analytical procedure of open coding, selective coding and theoretical coding. In GT, the initial basis for the study is to understand a particular social phenomenon in order to build a theory upon it. Inductive and repeated analysis focused on the children’s actions in combination with the actual natural affordances. In formulating the theory, the findings of garden affordances for children were evaluated relatively with these theoretical concepts: environmental child-friendliness (ECF), the zone of proximal development (ZPD), behavioural insideness, and connectedness to nature/place. Firstly, the results in study I showed that the relationship between nature and greenery differs according to residence and gender. The children living in a rural area (N= 34 in Paltamo, Kainuu) were more likely to mention natural places as their favourites than did their suburban counterparts (N=42 in Helsinki). Illustratively, rural children claimed to know the forest trees by name more often than the suburban children. In addition, the rural children understood mankind as part of nature, whereas suburban children were more likely to disagree with this claim. The group differences reported were statistically significant. The girls were, in general, more interested in plants than the boys. Alarmingly, 36% of the boys did not understand that plants are essential for human life. The girls understood better that plants are vital for human life. Second, results in the following studies II and III in the garden camp context showed that the versatility of affordances offered plenty of opportunities for building the nature-child relationship. The garden fostered social interactions by offering plentiful materials in a varied space. The variability and abundance of affordances boosted ZPD through scaffolding – learning together and from more experienced peers while using the affordances proved noteworthy in learning and passing on new skills. The essential factors that had a contributory role in the process of becoming empowered players within the setting were: sufficient time, the possibility of child-directed play and a space with a versatility of affordances available for use. With these factors, the garden affordances brought about 14 various play types. Trees were the most significant elements of the research site in fostering a relationship with nature. They answered children’s situational and individual needs by offering ideas, challenge, materials, and space for play. Wooden material affordances offered props and loose parts for different play needs. The trees possessed qualities equivalent to children’s needs for building self-confidence and emotion regulation, competence and belonging, creativity, excitement and affection. Climbing trees offered the children the challenge of handling risks autonomously. Consequently, trees serve well as indicator plants in assessing the children's connectedness to place. The children’s whole process of connecting with the place was captured, and the actual phases of this evolving connectedness are presented. Along with the concept of behavioural insideness that represents the behaviour of a child when she/he feels connected with a place, this study identifies the preceding phases: the initial phase as outsiders, then searchers, and finally the proactive insiders. In the first phase, as an outsider, the still insecure children looked for comfort around the vegetation. Tall trees were visibly inviting, offering an asylum or a shield before the children gained the confidence to start the searcher phase. The searchers, as the name implies, were constantly exploring their surroundings and the phase also involved showing off one's skills to make friends. For the searchers, the garden affordances offered versatility for choosing suitable materials and space. The biodiversity of the place was key to satisfying children’s needs by offering suitable affordances; it successfully fostered the development of behavioural insideness within two weeks, and this ultimately led to a strong connectedness to place. In the last phase as insiders, long-term play utilizing a wide variety of natural materials was typical, and the children behaved both spontaneously and imaginatively. The adults and peers had an effect on the children's connection process and to the actualization of garden's affordances, affecting the ECF. Impetus, which triggered the use of affordances, was either personal or situational. Some of the obstacles came from personal shortcomings, such as lack of interest or experience, or from fears and/or dislikes. Common obstacles from adults included a desire to move forward with the planned programme or an appeal to safety and rules. The development of a grounded theory, the IAO theory, outlines possible combinations of place-based impetuses, obstacles and affordances, all of which have an effect on the children’s process of connecting to place. The theory is an equation, which makes it user-friendly in assessing and planning children’s nature-based activities and environments. In addition, the theoretical framework of ‘Affordances channel connectedness to place’ opens up the external and internal preconditions necessary for children before they start utilizing the existing affordances, their three-phased process towards connectedness to place, and the manifestations of the final stage, behavioural insideness. Finally, a child-centred implication, PIT (Place-based, Intention and Time), provides guidelines to help adults to plan and conduct place-based, situational-sensitive nature activities for children. With these three GT outcomes, children’s connection to nature can be well supported.
  • Rodríguez Serrano, Juan José (Helsingin yliopisto, 2020)
    In a changing global climate where the transport and partitioning of hazardous chemicals are expected to be altered, it is crucial to deepen our understanding of the potential impacts of anthropogenically-derived pollutants on the marine environment and its food webs. Microbial communities constitute the basic levels of marine food webs, playing a major role in essential biochemical cycles that determine the ecosystem functioning. Due to their vast metabolic versatility and adaptability, bacteria inhabit a wide range of environments, and contaminated waters and sediments are no exception. The present doctoral thesis addresses the problematic of environmental pollution originating from anthropogenic activities in a coastal marine system, particularly in the context of climate change. To that end, the focus was laid on the basal links of marine food webs: bacterial communities and their function. The Baltic Sea, and more specifically the Bothnian Sea, was chosen as study system to investigate the response of naturally occurring bacterial communities under elevated concentrations of organic pollutants, on one hand, and mercury, on the other. The Baltic Sea is a marine/brackish system strongly influenced by terrestrial runoff. This is expected to be exacerbated as a result of climate change, which will substantially increase the concentration of terrestrial dissolved organic matter (tDOM). In this context, we carried out laboratory experiments where two main factors were controlled: tDOM and environmental pollutants of particular concern. Two different metagenomic approaches were employed to study the taxonomic composition and functional properties of naturally occurring bacterial communities: 16S rRNA amplicon sequencing and shotgun metagenomics. In a mesocosm experiment, the combined effects of increased tDOM concentration and a mixture of persistent organic pollutants (POPs) were evaluated by 16S rRNA amplicon metagenomics. Shifts in the taxonomic composition of bacterioplankton communities were detected as a result of the addition of tDOM, POPs, and the combination of both factors. Similarly, shotgun metagenomics was employed in a microcosm experiment in order to study the role of bacterioplankton communities in the formation of methylmercury (MeHg) under oxic conditions, as well as to determine the effect of increasing concentrations of tDOM in such a process. MeHg formation was found to occur within the first hours after the addition of Hg(II), as well as being stimulated under increasing tDOM levels. In addition, the structure of bacterial communities inhabiting contaminated sediments from a coastal area of the Bothnian Sea was studied by 16S rRNA amplicon metagenomics. The bacterial community structure was linked to different loads of POPs originating from local industrial activities, where a number of bacterial taxa were found to strongly correlate with particular POPs. Thus, the potential use of bacterial communities as bioindicators of environmental pollution was evaluated. The results presented in this doctoral thesis have important implications on our understanding of the role of complex bacterial communities in relation to the bioavailability and partitioning of environmental pollutants of major concern, and how these interactions may be altered in a future Baltic Sea climate.
  • Xie, Long (Helsingin yliopisto, 2020)
    Urban greening has gained increasing popularity in cities, in order to create a more livable environment. Vegetated building envelope (VBE) might provide additional green spaces, delivering ecoservices, such as storm water management, air pollution mitigation, energy conservation, and urban heat island effect reduction. Considering the growing conditions on VBEs are generally harsh, it is becoming imperative to investigate how to maintain plants on VBEs at their optimum. The present PhD project focused on maintaining plants in VBE systems by inoculating two beneficial microbes in the substrate, i.e., Rhizophagus irregularis and Bacillus amyloliquefaciens. R. irregularis is an arbuscular mycorrhizal fungus (AMF) residing in plant roots, and B. amyloliquefaciens is a spore-forming bacterium residing outside root surface. Both microbes can help host plants against nutrient deficiency, pathogen infection, drought, and high salinity. In return, the host plants support the microbes with root exudates rich in photosynthetic compounds. This doctoral dissertation consists of three studies. The first study confirmed the survival and colonization of both microbes on VBEs, and R. irregularis was speculated to support growth of B. amyloliquefaciens. It also suggested that substrate pH and biochar amendment could influence R. irregularis colonization. The second study showed that most tested plants in the lab could co-host both microbes, and R. irregularis colonization was improved by B. amyloliquefaciens. Most importantly, co-inoculation of the microbes led to higher shoot biomass and photosynthetic efficiency than single-inoculation. The last study verified that plant growth-promotion via co-inoculation was achieved on vegetated roofs. Moreover, R. irregularis colonization was affected by plant species, planting methods and their interactions, while B. amyloliquefaciens density was affected only by plant species. This doctoral dissertation provides valuable references to build and maintain more stress-tolerant and vigorously growing plants on VBEs, in the hope of making VBE application more affordable and widely used.
  • Hautakangas, Sami (Helsingin yliopisto, 2020)
    The main theme in this dissertation is to determine the means of achieving the Baltic Sea Action Plan targets, with an emphasis on municipal wastewaters. Thus, the nitrogen and phosphorus reduction potentials of wastewater treatment plants and costs of nutrient reductions are calculated. The nutrient reduction potential is huge for municipal wastewater. Furthermore, abating nutrients in wastewater treatment plants is cheaper than previously thought. In particular, phosphorus abatement costs are much lower than those in agriculture. A numerical model is built to demonstrate that a considerable share of the targets of the Baltic Sea Action Plan can be met by nutrient abatement in wastewater treatment plants. Moreover, it is shown that with properly designed initial allocations, a nutrient trading scheme can even out the cost burden between wastewater treatment plants. However, transaction costs may play a significant role in nutrient trading in the Baltic Sea region. With an analytical model, it is demonstrated that if a water utility has market power, a tightening nutrient policy may decrease the price of potable water but increase the wastewater tariff. Based on the analytical model, a numerical model is built to illustrate that households connected to small water utilities face higher prices and higher price increases associated with environmental protection measures than do households connected to large water utilities. Finally, it is shown when the level of nutrient abatement reaches the upper limit, the costs water utilities face no longer depend on the instrument applied.
  • Deng, Biar (Helsingin yliopisto, 2020)
    Rainfed agriculture is a vital land use practice for food security and economic development in most of drylands, but particularly in sub-Saharan Africa (SSA). However, it is becoming an increasingly uncertain and inefficient practice in SSA because of climate change and extremes (i.e. low and erratic rainfall, high temperatures, floods, and drought occurrence), and low soil fertility and water supply. For example, yields of sorghum, which is the main staple food crop in South Sudan, are dwindling under rainfed cultivation in its main production areas in the north of the country due to the previously mentioned factors. Nevertheless, soil amendment materials, such as biochars, along with integration of sorghum production into agroforestry systems, which can improve soil fertility and water storage capacity, could assist in improving the crop yields. In this dissertation, the effects of Acacia seyal-based agroforestry and addition of biochar on soil water retention and supply and on sorghum yields were examined. The research focused on 1) the potential of using biochar as a soil amendment combined with A. seyal-based agroforestry in a field experiment, 2) the effect of biochar on alleviating water stress on sorghum yield in greenhouse conditions, and 3) simulation of the potential effect of biochar amendments on improving sorghum biomass and grain yield, especially as indicated by differences in yield between wet and dry years. The two-year agroforestry field experiment (Paper I) was carried out at Magara Village north of Renk in South Sudan, during the growing seasons of 2011 and 2012. The split block experiment included three A. seyal tree density treatments: no trees; scattered trees (100 trees ha-1) and dense trees (400 trees ha-1) and two biochar amendment treatments (0 t ha-1 and 10 t ha-1). The soil consisted of silty loam underlain by clay, and the biochar source was A. seyal trees. A soil analysis showed that agroforestry resulted in lower soil pH, N, and total and exchangeable Ca2+ contents and higher C/N ratios compared to sole sorghum cultivation. The application of biochar significantly increased the soil C and exchangeable K+ contents as well as the pedotransfer-derived field capacity and plant available water contents, but significantly decreased the content of exchangeable Ca2+ and cation exchange capacity. The inclusion of A. seyal trees significantly decreased the sorghum grain yields, and the effect of biochar on grain yield compared to sole sorghum cultivation without amendment was not significant. The Land Equivalent Ratio (LER, the sum of the fractions of the intercropped yields divided by the sole-crop yields) value was 0.3 for dense A. seyal intercropping combined with biochar in both 2011 and 2012 and with scattered A. seyal intercropping in 2011, but it was twofold greater (0.6) in 2012 with biochar amendment. The greenhouse experiment (Paper II) was carried out at the Viikki Campus, Helsinki, Finland, during May–December 2011. The main factor was drought stress with three levels of soil moisture content: 60% of field capacity (well-watered), 40% (medium drought) and 20% (severe drought). The same type A. seyal biochar, in the same amounts as applied in the field experiment (0 t ha-1 and 10 t ha-1), was used. Drought stress had a significant effect on sorghum gas exchange but not on sorghum stomatal traits. The stomatal conductance and photosynthesis and transpiration rates were all significantly reduced under severe drought compared to values found in plants that were under medium drought or well-watered. The photosynthetic water use efficiency (WUE) increased with the level of drought stress. Drought stress significantly reduced the sorghum biomass and grain yields compared to those observed in well-watered plants. Biochar addition did not have a significant effect on any of sorghum stomatal traits, gas exchange or grain yield. The biochar/sorghum simulation study (Paper III) was carried out using the water-driven crop-growth model AquaCrop (version 6.1). The model was parameterized for the field experiment site and soil conditions. Soil fertility stress parameters were adjusted so that simulated biomass and grain yield values best matched the levels recorded in the field experiment. Climate data for 2011 and 2012, both wet years, and for 1990, an extremely dry year, were extracted from the Climate Forecast System Reanalysis (CFRS) online dataset. The effects of biochar were simulated using the changes in soil hydraulic properties (increases in field capacity, available water capacity and saturated conductivity) reported in a published meta-analysis study. Generally, the simulated biochar amendments having the greatest effect on soil hydraulic properties increased the water content of the rooting depth in all three years, but an increase in sorghum production was only discernible for 1990. The results from paper I showed that sorghum yields are lowered when the crop is grown in agroforestry systems. As sorghum is not tolerant of shade, the reduction in sorghum production with increasing tree density was probably due to canopy cover and shading. This effect thus overrode any benefit of having the trees in the cultivation system. The results from paper II indicated that biochar has no significant effect on alleviating drought stress on sorghum production and grain yields, while the results from paper III showed biochar, while improving soil hydraulic properties, only resulted in increased sorghum biomass production and grain yield in very dry years. Overall, the results from this study showed that the propounded benefits of agroforestry and biochar need further study and critical assessment, particularly in semi-arid environments where the water supply through rainfall is low and erratic but the water demand is constantly high. The results may well vary with different crops and agroforestry systems, as well as with different soil types and the type and dose of biochar. Furthermore, the results may only become apparent with sufficient time and therefore long-term studies are needed.

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