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The Influence of Microbial Degradation of Biochar in Soil on its Physico-chemical Properties
Kurková, Marie ; Weidlich, Tomáš (referee) ; Kalina, Michal (advisor)
This master‘s thesis studies the different factors that can affect biochar in soil and cause its degradation. These factors include irrigation, root exudates and the action of microorganisms. In the experimental part, the degradation of biochar in the soil environment was studied in two ways, firstly without the action of microorganisms, where the effect of irrigation was simulated by leaching biochar in ultrapure distilled water and model rainwater, and the effect of root exudates was simulated by extracting of biochar in citric acid as a model root exudate of maize sown. The extracted biochar solutions without prior cultivation in soil were characterized by pH, conductivity, UV-VIS analysis and elemental analysis. The biochar residues after extractions were characterized for morphology by SEM, structural differences by FTIR, and organic and mineral content by TGA analysis. The biochar samples after cultivation in soil were subjected to extractions under the same conditions and the same analyses were performed. The effect of cultivation in soil on biochar resulted in a change in elemental composition, a decrease in biochar alkalinity and changes in the ratio of organic matter and mineral fraction were observed. The decrease in pH and conductivity of biochar was mainly related to potassium leaching. The structural and morphological analysis indicated that there is no significant degradation of the structure of the biochar due to washing or cultivation in soil, but there is a partial fouling of the biochar pores by low molecular weight impurities from the soil. These results suggest a short-term action of biochar in soils as a source of nutrients (potassium, phosphorus) and, conversely, a long-term action as a soil conditioner.
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The importance of root exudates for crop cultivation under climate change
Schnürer, Oliver ; Albrechtová, Jana (advisor) ; Tylová, Edita (referee)
Root exudates are compounds secreted by plant roots that can help plants, for example, to obtain nutrients from the soil or to increase their resistance to biotic stress. Root exudates can thus hide a great potential that can be used in agriculture. As human population grows, there is increasing pressure on agriculture, which must provide enough food to feed the global population, thus ensuring food security. Until now, agricultural activity has tried to satisfy this demand by intensification of agriculture, mainly by breeding highly productive crops when using intensive fertilizing, but the theoretical possible benefits of root exudates in breeding remained overlooked. Intensive farming practices can further exacerbate the impacts of ongoing climate change, for example by increasing soil carbon mineralization or reducing biodiversity. By using root exudates in the production of crops, it will be possible to achieve a higher nutrient content in soil, as well as a higher resistance of crops to pests, without the aforementioned negative impacts of intensive agriculture. In this work, I tried to describe the main functions of root exudates, their reaction to increased CO2 concentration in the atmosphere, their stress response caused by stressors of climate change and their theoretical use in...
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Enzymatic Degradation of Biochar
Zmijová, Marie ; Enev, Vojtěch (referee) ; Kalina, Michal (advisor)
Human prosperity is inextricably linked to healthy soil. It turns out that the application of biochar improves soil properties and, as a result, also the growth and yield of plants. The presence and activity of soil biota contributes to soil quality, but it also excretes compounds that can degrade biochar. Experiments simulating the action of enzymes and root exudates were carried out in order to find out whether there are physico-chemical changes in biochar. Three biochars, which were chosen for this purpose were degraded using an H2O2 solution, simulating enzymatic action. Samples were subsequently analyzed using TGA, FTIR, SEM and contact angle measurement. It was found that the amount and type of degraded biochar matter depends on the parameters of its production. The amount of functional groups containing oxygen on the surface of biochar rises due to enzymatic oxidation and the surface’s hydrophobicity decreases as a result. An extraction test using citric acid, a root exudate representative, showed that the sample had been washed more effectively, leading to a higher proportion of organic matter in the biochars. In the obtained leachates, the amount of elements released from the biochar was monitored using ICP-OES. The initial washing led to the release of the largest amount of micro and macro elements, which caused a decrease in the pH value of the solution and an increase in conductivity. The pH value of the solution had a major influence on the amount of released multivalent elements (Ca, Mg). The combination of these changes that may occur in the soil system probably does not change the desired effect of biochar and its use may be beneficial in the long term.
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Lignite degradation in soil environment
Vybíralová, Natálie ; Salaš, Petr (referee) ; Pekař, Miloslav (advisor)
This Master‘s thesis deals with the topic of coal and, more precisely South Moravian lignite. Lignite was degraded by using biological and chemical methods, which included oxidation of lignite with hydrogen peroxide. Special attention was paid to the degradation of lignite in the soil environment, where the simulation of natural fields conditions took place for 6 months. Furthermore, a simulation of root exudates was carried out using organic acids, which occur naturally in the soil environment and directly affect life in the soil and around the roots of the plant. Lignite degradation was also performed using a cultured bacterial solution and then using a commercially available horticultural products to increase the activity of soil microorganisms and promote growth.
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Effect of soil C:N:P stoichiometry on plant-microbe-soil interactions
CÁRDENAS HERNÁNDEZ, Julián Fernando
The effect of C:N:P stoichiometry on plant-microbe-soil interactions was studied using glasshouse experiments to maintain constant environmental conditions and manipulate plant and soil characteristics. Plants with different economic strategies were studied on soils with different C:N:P stoichiometry due to C enrichment. This allowed for various plant-soil interactions, which were used to study the strongest links between plants, microbes, and soil. Subsequently, the role of C addition in the plant-exudates-microbe-soil interactions was evaluated, including the correlation of foliar isotopic C and N composition with plant biomass and soil N availability. Finally, plant- soil communication was altered by fertilizing plant leaves without changing soil conditions. In this way, we were able to determine the role of plant C:N stoichiometry in the priming effect of the rhizosphere and detritusphere.
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The Influence of Microbial Degradation of Biochar in Soil on its Physico-chemical Properties
Kurková, Marie ; Weidlich, Tomáš (referee) ; Kalina, Michal (advisor)
This master‘s thesis studies the different factors that can affect biochar in soil and cause its degradation. These factors include irrigation, root exudates and the action of microorganisms. In the experimental part, the degradation of biochar in the soil environment was studied in two ways, firstly without the action of microorganisms, where the effect of irrigation was simulated by leaching biochar in ultrapure distilled water and model rainwater, and the effect of root exudates was simulated by extracting of biochar in citric acid as a model root exudate of maize sown. The extracted biochar solutions without prior cultivation in soil were characterized by pH, conductivity, UV-VIS analysis and elemental analysis. The biochar residues after extractions were characterized for morphology by SEM, structural differences by FTIR, and organic and mineral content by TGA analysis. The biochar samples after cultivation in soil were subjected to extractions under the same conditions and the same analyses were performed. The effect of cultivation in soil on biochar resulted in a change in elemental composition, a decrease in biochar alkalinity and changes in the ratio of organic matter and mineral fraction were observed. The decrease in pH and conductivity of biochar was mainly related to potassium leaching. The structural and morphological analysis indicated that there is no significant degradation of the structure of the biochar due to washing or cultivation in soil, but there is a partial fouling of the biochar pores by low molecular weight impurities from the soil. These results suggest a short-term action of biochar in soils as a source of nutrients (potassium, phosphorus) and, conversely, a long-term action as a soil conditioner.
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Importance of root exudates in plant-soil interactions
Horčičková, Veronika ; Münzbergová, Zuzana (advisor) ; Janoušková, Martina (referee)
Plant roots are in constant contact with soil microorganisms and fungi, and they come in contact with soil fauna and the roots of other plants. All components of the soil biota communicate with each other. When it comes to plants it is often a chemical communication through root exudates, chemicals that plants release into the soil. Through root exudation, plants also affect the abiotic component of the soil, which helps them to obtain nutrients. The production of root exudates is important in attracting symbionts and beneficial organisms and, conversely, in repelling or killing pathogens and parasites. Thanks to root exudates, plants can recognize neighbouring plants, suppress the growth of competitors, or avoid competition with kin, and parasitic plants use root exudates as signals to find its host. By the action of root exudates, plants create their own community of microorganisms and fungi in the rhizosphere, adjust the availability of nutrients and thus actively change living conditions in the soil. This bachelor thesis focuses on plant interactions through root exudates and mentions the ways in which root exudation can be studied. The following diploma thesis will discuss the influence of root exudates of invasive plants on the native plant community.
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Vliv kořenových exudátů na dekompozici rozpuštěné organické hmoty v rašeliništi
ŽAMPACH, Ondřej
The aim of this thesis was to assess the effect of root exudates on the biodegradability of dissolved organic matter. The experiment was done in laboratory conditions, using the dissolved organic matter sampled in a spruce swamp forest located in Šumava National Park and an artificial mixture of root exudates prepared according to known composition of root exudates released by peatland plants. Main hypothesis was that the input of root exudates into the peatland pore water will affect decomposition of less-degradable dissolved organic matter, with the resulting effect dependent on the quantity and quality (C:N ratio) of the input.
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