Made available in DSpace on 2014-06-11T19:23:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-09Bitstream added on 2014-06-13T18:50:27Z : No. of bitstreams: 1 silva_efl_me_jabo.pdf: 383641 bytes, checksum: 59b012609413039433f00a07564e3f1e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo teve como objetivo avaliar o efeito de doses crescentes de lodo de esgoto (LE), aplicadas por treze anos em Latossolo Vermelho eutroférrico, nos atributos biológicos e bioquímicos, nos teores de elementos-traço do solo e no acúmulo destes pelas plantas daninhas. O experimento foi conduzido em condições de campo, em Jaboticabal-SP, utilizando-se delineamento em blocos casualizados com quatro doses de LE (0, 5, 10 e 20 Mg ha-1, base seca) e cinco repetições. As amostras de solo (0 a 10 cm), plantas daninhas e resíduos culturais foram coletadas em outubro de 2010, 130 dias após a colheita do milho. Os valores do carbono da biomassa microbiana não variaram em função das doses de LE, porém os valores de respiração basal e quociente metabólico foram maiores nas doses 10 e 20 Mg ha-1. Para o quociente microbiano, o menor valor foi observado na dose 0 Mg ha-1 de LE. Os teores totais de Cd e Cr no solo não variaram em função das doses de LE. De forma contrária, os teores totais de Ni e Pb no solo aumentaram proporcionalmente até a dose 10 Mg ha-1. A atividade das enzimas desidrogenase, arilsulfatase, celulase e urease não variou. Porém a atividade hidrolítica do diacetato de fluoresceína (FDA) e da fosfatase ácida foram maiores na dose 20 Mg ha-1. Em relação às plantas daninhas e a palha do milho a adição de LE por longo período causou efeitos semelhantes nos valores da produção de matéria seca e nos teores totais de Cd, Cr, Ni e Pb. Entretanto, os teores acumulados de Cd, Ni e Pb na parte aérea dos grupos de planta daninha aumentaram até a dose 10 Mg ha-1 diferindo da testemunha. O LE causou atividade biológica negativa no solo nas doses 10 e 20 Mg ha-1. A atividade foi indicada pelos aumentos na respiração basal, na atividade hidrolítica do FDA e na atividade da fosfatase ácida. Entretanto, o aumento do quociente metabólico e a diminuição do quociente microbiano indicaram estar havendo estresse / This study aimed to evaluate the effect of increasing doses of sewage sludge (SS), applied for thirteen years in Oxisol in biological and biochemical attributes, the levels of trace elements in soil and accumulation of weed. The experiment was conducted under field conditions in Jaboticabal, using a randomized block design with four doses of SS (0, 5, 10 and 20 Mg ha-1, dry basis) and five replicates. Soil samples (0-10 cm), weeds and crop residues were collected in October 2010, 130 days after the corn harvest. The values of microbial biomass carbon did not vary with the doses of SS, but the values of basal respiration and metabolic quotient were higher in doses 10 and 20 Mg ha-1. For the microbial quotient, the lowest value was observed at the dose 0 Mg ha-1 SS. Total concentrations of Cd and Cr in the soil did not vary with the doses of LE. Conversely, the total concentration of Ni and Pb in soil increased proportionally to the dose of 10 Mg ha-1. The activity of enzymes dehydrogenase, arylsulfatase, cellulase and urease did not change. However, the hydrolytic activity of the fluorescein diacetate (FDA) and acid phosphatase were higher in the dose 20 Mg ha-1. In relation to weeds and straw corn, adding SS for a long period caused similar effects on the values of dry matter production and total contents of Cd, Cr, Ni and Pb. However, the accumulated contents of Cd, Ni and Pb in the aerial part of the weed groups increased until the dose of 10 Mg ha-1 differed from the control. The SS has caused negative biological activity in soil at doses 10 and 20 Mg ha-1. The activity was indicated by increases in respiration, FDA hydrolytic activity and acid phosphatase activity. However, the increase metabolic quotient and decrease of the ratio having indicated that microbial stress

Orientador: Wanderley Jose de Melo / Coorientador: Gabriel Maurício Peruca de Melo / Banca: Ademir Sérgio Ferreira de Araújo / Banca: Ely Nahas / Resumo: Este estudo teve como objetivo avaliar o efeito de doses crescentes de lodo de esgoto (LE), aplicadas por treze anos em Latossolo Vermelho eutroférrico, nos atributos biológicos e bioquímicos, nos teores de elementos-traço do solo e no acúmulo destes pelas plantas daninhas. O experimento foi conduzido em condições de campo, em Jaboticabal-SP, utilizando-se delineamento em blocos casualizados com quatro doses de LE (0, 5, 10 e 20 Mg ha-1, base seca) e cinco repetições. As amostras de solo (0 a 10 cm), plantas daninhas e resíduos culturais foram coletadas em outubro de 2010, 130 dias após a colheita do milho. Os valores do carbono da biomassa microbiana não variaram em função das doses de LE, porém os valores de respiração basal e quociente metabólico foram maiores nas doses 10 e 20 Mg ha-1. Para o quociente microbiano, o menor valor foi observado na dose 0 Mg ha-1 de LE. Os teores totais de Cd e Cr no solo não variaram em função das doses de LE. De forma contrária, os teores totais de Ni e Pb no solo aumentaram proporcionalmente até a dose 10 Mg ha-1. A atividade das enzimas desidrogenase, arilsulfatase, celulase e urease não variou. Porém a atividade hidrolítica do diacetato de fluoresceína (FDA) e da fosfatase ácida foram maiores na dose 20 Mg ha-1. Em relação às plantas daninhas e a palha do milho a adição de LE por longo período causou efeitos semelhantes nos valores da produção de matéria seca e nos teores totais de Cd, Cr, Ni e Pb. Entretanto, os teores acumulados de Cd, Ni e Pb na parte aérea dos grupos de planta daninha aumentaram até a dose 10 Mg ha-1 diferindo da testemunha. O LE causou atividade biológica negativa no solo nas doses 10 e 20 Mg ha-1. A atividade foi indicada pelos aumentos na respiração basal, na atividade hidrolítica do FDA e na atividade da fosfatase ácida. Entretanto, o aumento do quociente metabólico e a diminuição do quociente microbiano indicaram estar havendo estresse / Abstract: This study aimed to evaluate the effect of increasing doses of sewage sludge (SS), applied for thirteen years in Oxisol in biological and biochemical attributes, the levels of trace elements in soil and accumulation of weed. The experiment was conducted under field conditions in Jaboticabal, using a randomized block design with four doses of SS (0, 5, 10 and 20 Mg ha-1, dry basis) and five replicates. Soil samples (0-10 cm), weeds and crop residues were collected in October 2010, 130 days after the corn harvest. The values of microbial biomass carbon did not vary with the doses of SS, but the values of basal respiration and metabolic quotient were higher in doses 10 and 20 Mg ha-1. For the microbial quotient, the lowest value was observed at the dose 0 Mg ha-1 SS. Total concentrations of Cd and Cr in the soil did not vary with the doses of LE. Conversely, the total concentration of Ni and Pb in soil increased proportionally to the dose of 10 Mg ha-1. The activity of enzymes dehydrogenase, arylsulfatase, cellulase and urease did not change. However, the hydrolytic activity of the fluorescein diacetate (FDA) and acid phosphatase were higher in the dose 20 Mg ha-1. In relation to weeds and straw corn, adding SS for a long period caused similar effects on the values of dry matter production and total contents of Cd, Cr, Ni and Pb. However, the accumulated contents of Cd, Ni and Pb in the aerial part of the weed groups increased until the dose of 10 Mg ha-1 differed from the control. The SS has caused negative biological activity in soil at doses 10 and 20 Mg ha-1. The activity was indicated by increases in respiration, FDA hydrolytic activity and acid phosphatase activity. However, the increase metabolic quotient and decrease of the ratio having indicated that microbial stress / Mestre

Ethanol is used as fuel in neat form in some countries (Brazil and India) or blended with gasoline (Europe, Canada and the United States). The benefits of ethanol use include octane enhancement, a cleaner environment and a secure renewable energy supply. BTEX compounds (benzene, toluene, ethylbenzene, m-xylene, p-xylene and o-xylene) are aromatic hydrocarbons present in gasoline. The fate of these compounds in the environment is of great health concern due to their carcinogenic (benzene) and toxic properties, and due to their high solubility in water compared to the other gasoline hydrocarbons. Ethanol present in gasoline may affect BTEX degradation, in an event of a spill into the subsurface environment. To address the effects of ethanol on subsurface microorganisms, microbial activity and growth in the presence of ethanol (concentrations ranging 0 to 70% v/v) were assessed. Microcosms studies showed that ethanol at concentration ranging 0. 5 to3% (v/v) enhanced microbial activity and did not interfere inmicrobial growth at 10oC temperature, when another source of carbon was present (glucose). Ethanol at 0. 5% concentration enhanced microbial activity over water soluble gasoline components and R2A medium combined. Both microbialactivity and growth were not detected at ethanol concentrations equal and above 5%. Biodegradation study was conducted, in which subsurface material and ground water were exposed to BTEX and ethanol at 0. 5 and 1. 5% (v/v) concentration. The controls had BTEX alone and ethanol alone, sterile and nutrient-free. Total BTEX degradation was observed whenever ethanol was absent. Ethanol and BTEX were simultaneously degraded, however in microcosms containing 0. 5% ethanol, BTEX degradation was slowed, compared to microcosms without ethanol. Competition for inorganic nutrients was the major problem in slowed BTEX degradation in the presence of ethanol. In microcosms where 1. 5% ethanol was present, BTEX compounds and ethanol degradation were not observed.

Ethanol is used as fuel in neat form in some countries (Brazil and India) or blended with gasoline (Europe, Canada and the United States). The benefits of ethanol use include octane enhancement, a cleaner environment and a secure renewable energy supply. BTEX compounds (benzene, toluene, ethylbenzene, m-xylene, p-xylene and o-xylene) are aromatic hydrocarbons present in gasoline. The fate of these compounds in the environment is of great health concern due to their carcinogenic (benzene) and toxic properties, and due to their high solubility in water compared to the other gasoline hydrocarbons. Ethanol present in gasoline may affect BTEX degradation, in an event of a spill into the subsurface environment. To address the effects of ethanol on subsurface microorganisms, microbial activity and growth in the presence of ethanol (concentrations ranging 0 to 70% v/v) were assessed. Microcosms studies showed that ethanol at concentration ranging 0. 5 to3% (v/v) enhanced microbial activity and did not interfere inmicrobial growth at 10oC temperature, when another source of carbon was present (glucose). Ethanol at 0. 5% concentration enhanced microbial activity over water soluble gasoline components and R2A medium combined. Both microbialactivity and growth were not detected at ethanol concentrations equal and above 5%. Biodegradation study was conducted, in which subsurface material and ground water were exposed to BTEX and ethanol at 0. 5 and 1. 5% (v/v) concentration. The controls had BTEX alone and ethanol alone, sterile and nutrient-free. Total BTEX degradation was observed whenever ethanol was absent. Ethanol and BTEX were simultaneously degraded, however in microcosms containing 0. 5% ethanol, BTEX degradation was slowed, compared to microcosms without ethanol. Competition for inorganic nutrients was the major problem in slowed BTEX degradation in the presence of ethanol. In microcosms where 1. 5% ethanol was present, BTEX compounds and ethanol degradation were not observed.

Northern peatlands are large repositories of carbon and little is known about the effect the microbial community has on carbon mineralization rates, and there is concern that a loss of microbial diversity due to environmental change may lead to reduced ecosystem functioning. Microbial communities vary among peatland types and abiotic variables such as temperature and pH have a large influence on carbon dioxide production, but distinguishing between abiotic controls and the role of microbial community structure has proved challenging. Microbial activity and community composition was characterized in three peatlands within the James Bay Lowlands, Ontario. Similar dominant microbial taxa were observed at all three peatlands despite differences in nutrient content and substrate quality and geographic location. In contrast, microbial activity differed among the sites, indicating that it is influenced by the quality of the peat substrate and the presence of microbial inhibitors. A series of reciprocal field and laboratory transplant experiments were conducted at a rich and poor fen near White River, Ontario to more explicitly distinguish between the abiotic and microbial controls on carbon mineralization. The effect of transplantation differed between the laboratory and field studies and when viewed individually could lead to different interpretations of the effect of substrate change. Surprisingly, intensive sampling within both fens was unable to reveal a difference between the rich and poor fen microbial community due to high within site temporal and spatial variation. Thus studies with small sampling effort will have a very incomplete understanding of microbial community structure and thus microbial ecology. A reciprocal sterilization transplant experiment was also conducted to examine how different microbial communities adapted to various peat substrates influenced C-mineralization patterns. Post-inoculation/incubation bacterial communities across peatlands converged towards a similar community structure, suggesting that abiotic variables are the dominant control on peatland microbial activity and community composition. The studies presented in this thesis collectively show that across a broad range of temperate and sub-arctic peatland types dominant members of the microbial community are generally similar, and decomposition rates can be predicted by broader controlling environmental factors rather than temporal niche or distributional constraints of the microbial community.

Northern peatlands are large repositories of carbon and little is known about the effect the microbial community has on carbon mineralization rates, and there is concern that a loss of microbial diversity due to environmental change may lead to reduced ecosystem functioning. Microbial communities vary among peatland types and abiotic variables such as temperature and pH have a large influence on carbon dioxide production, but distinguishing between abiotic controls and the role of microbial community structure has proved challenging. Microbial activity and community composition was characterized in three peatlands within the James Bay Lowlands, Ontario. Similar dominant microbial taxa were observed at all three peatlands despite differences in nutrient content and substrate quality and geographic location. In contrast, microbial activity differed among the sites, indicating that it is influenced by the quality of the peat substrate and the presence of microbial inhibitors. A series of reciprocal field and laboratory transplant experiments were conducted at a rich and poor fen near White River, Ontario to more explicitly distinguish between the abiotic and microbial controls on carbon mineralization. The effect of transplantation differed between the laboratory and field studies and when viewed individually could lead to different interpretations of the effect of substrate change. Surprisingly, intensive sampling within both fens was unable to reveal a difference between the rich and poor fen microbial community due to high within site temporal and spatial variation. Thus studies with small sampling effort will have a very incomplete understanding of microbial community structure and thus microbial ecology. A reciprocal sterilization transplant experiment was also conducted to examine how different microbial communities adapted to various peat substrates influenced C-mineralization patterns. Post-inoculation/incubation bacterial communities across peatlands converged towards a similar community structure, suggesting that abiotic variables are the dominant control on peatland microbial activity and community composition. The studies presented in this thesis collectively show that across a broad range of temperate and sub-arctic peatland types dominant members of the microbial community are generally similar, and decomposition rates can be predicted by broader controlling environmental factors rather than temporal niche or distributional constraints of the microbial community.

Orientador: Cassiana Maria Reganhan Coneglian / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-22T10:59:00Z (GMT). No. of bitstreams: 1 Rego_AnaPaulaJustiniano_M.pdf: 1374824 bytes, checksum: f4374ed0d3dafb4fb76f0bd4a5678bc9 (MD5) Previous issue date: 2013 / Resumo: A ametrina é um herbicida utilizado em culturas de cana-de-açúcar no período de pré e pós emergência das plantas daninhas. É um composto persistente no meio ambiente, podendo lixiviar para água subterrânea e escoar para águas superficiais, provocando impacto na comunidade aquática. No presente trabalho avaliou-se a atividade microbiana em solo com histórico de aplicação da ametrina em cultivo de cana de açúcar, acrescidos de concentrações de solução de ametrina e biofertilizante comercial Microgeo. Coletaram-se três amostras de solo em área de cultivo de cana de açúcar, sendo o primeiro solo caracterizado como argiloso, o segundo arenoso, o terceiro arenoso, mas esterilizado em estufa a 106ºC. As concentrações utilizadas da ametrina nos experimentos foram de 8 e 12 ?g/mL e, as de biofertilizante foram 1, 5 e 10%. Para avaliar a atividade microbiana do solo utilizou-se o método respirométrico de Bartha que quantifica a geração de CO2 em mg/L e após o processo de biodegradação o método enzimático de hidrólise de FDA para avaliar a estimativa da atividade microbiana. Quantificou-se a população de bactérias heterotróficas e fungos expressos em UFC/g de solo antes e após o experimento de respirometria. Realizou-se teste de toxicidade com o organismo-teste Daphnia similis exposta ao herbicida ametrina nas concentrações 0,01; 0,1; 1; 10 e 100 ?g/L, do biofertilizante nas concentrações 1, 10 e 100% e do solo antes e após o experimento de respirometria, utilizando a fração solúvel. Realizou-se teste de fitoxicidade com a semente Lactuca sativa antes e após os experimentos de respirometria, utilizando a fração solúvel do solo. De acordo com os resultados obtidos pode-se concluir que a produção de CO2 foi maior em solo arenoso e menor em solo argiloso e em solo estéril. A estimativa microbiana pelo método de FDA foi maior em solo argiloso e arenoso e menor em solo estéril. O herbicida ametrina apresentou toxicidade ao organismo Daphnia similis. Antes e após os experimentos de respirometria, o solo não apresentou efeitos tóxicos à Daphnia simillis, não sendo possível calcular o CE50. Os solos antes e após experimentos de respirometria não apresentaram inibição na germinação e alongamento das raízes de Lactuca sativa. Conclui-se que o herbicida ametrina como citado na literatura é lentamente biodegradado no solo e a adição de biofertilizante Microgeo não corroborou com a sua biodegradação, mas favoreceu a atividade microbiana do solo / Abstract: The ametryn is an herbicide used on crops of sugar cane in the pre and post emergence weed. It is a compound persistent in the environment and can leach into groundwater and surface water to drain, causing impact on the aquatic community. In this study we evaluated the microbial activity in soil with a history of application of ametryn in cultivation of sugar cane, plus concentrations of ametryn solution and commercial bio fertilizer Microgeo. Three samples were collected from soil in sugar cane cultivation area, the first being characterized as clayey soil, the second sandy, and the third gritty but sterilized in an oven at 106 °C. The concentrations used in the experiments of ametryn were 8 and 12 ?g / mL, and the bio fertilizers were 1, 5 and 10 %. To evaluate the microbial activity in the soil it was used the Bartha respirometric method that quantifies the CO2 generation in mg / L and after the biodegradation the process of the enzymatic hydrolysis of FDA to evaluate the estimation of microbial activity. We quantified the population of heterotrophic bacteria and fungi expressed in CFU / g of soil before and after the respirometry experiment. We held a toxicity test with the Daphnia similis organisms test exposed to herbicide ametryn at 0.01, 0.1, 1, 10 and 100 mg/L of bio fertilizer concentrations 1, 10 and 100% and soil before and after the respirometry experiment, using the soluble fraction. A test of fitoxicity was performed with Lactuca sativa seed before and after the respirometry experiments using the soluble fraction of the soil. According to the obtained results it can be concluded that the CO2 production was higher on sandy soil and smaller in clayey soil and sterile soil. A method for estimating microbial FDA was higher in clay soil and sandy soil and lower in sterile. The herbicide ametryn showed toxicity to the organism Daphnia similis. Before and after the respirometry experiments, the soil showed no toxic effects to the Daphnia simillis, it is not possible to calculate the EC50. The soils, before and after respirometry experiments showed no inhibition on seed germination and root elongation of Lactuca sativa. It is concluded that the herbicide ametryn as quoted in the literature is slowly biodegraded in soil and the addition of the bio fertilizer Microgeo has not substantiated its biodegradation, but favored the soil microbial activity / Mestrado / Tecnologia e Inovação / Mestre em Tecnologia

Low microbial activity and associated nutrient cycling are concerns in agricultural problem soils. The objectives of this study were to investigate microbial response on problem soils to amendments, drying-wetting cycles, and the interaction of amendments and drying-wetting cycles. In this laboratory study, soil carbon dioxide (CO2) flux was measured from thermal desorption treated soils and saline soils in response to Proganics, spent lime, and composted beef manure applications. Microbial activity was measured through CO2 flux and its rate of change, permanganate oxidizable C, and residual inorganic nitrogen. Proganics had the greatest ability to elevate and sustain microbial activity on problem soils, but spent lime and compost had the greatest potential to improve microbial mediated nitrogen mineralization. In conclusion, spent lime and compost can be effective amendments for improving soil quality of saline and thermal desorption treated problem soils to increase microbial activity and associated nitrogen cycling.

Agroecosystem and cycling loops are open when considering the reutilization of inputs in farming areas. Non-renewable resources have been transformed or relocated from the air, water and land into the system and are flowing out as wastes rather than reusable, recyclable resources. Therefore, current trends in agriculture have moved towards more sustainable cultivation systems with higher efficiency of input use, since mineral nutrient losses due to runoff, leaching, erosion and gas emissions are leading to environmental degradation. A huge variety of materials can serve as a crop nutrient supply and they can be derived from different resources. The integrated plant nutrition system (IPNS) thrives tailoring plant nutrition and soil fertility management, taking advantage of the conjunctive and harmonious use of inorganic, organic and biological resources. We hypothesize that the synergetic effects of the combination of humic acid HA + biofertilizer will improve plant agronomic outcomes when comparing the application of each product alone. We initiated this project conducting a greenhouse study and field experiments evaluating the effects of an IPNS on corn. Posteriorly, the positive results in terms of corn biomass increasing, led to another greenhouse study addressing cannabis (Cannabis sativa L.) due its valuable biomass as an end/selling product. The greenhouse studies evaluated the effects of commercial synthetic fertilizer, HA, compost/manure teas and bioinoculant as inorganic, organic and biological resources, respectively, and their synergy on corn and cannabis early development under a period of water deficit stress. Generally, for both studies, when compared to the control values, the use of HA, biofertilizers and the integration of both substances generated significantly greater early season plant height, chlorophyll content and photosynthetic efficiency. The three-year field trial investigated the effects of nitrogen (N) fertilizer, HA, compost/manure teas and bioinoculant as inorganic, organic and biological resources, respectively and their synergy on corn growth. The individual and integrated application of HA and biofertilizer generally influenced corn development, to varying degrees. In 2017, corn height, NDVI, greenness and vigor were sensitive to the application of these biostimulants in different magnitudes and growth stages, however grain yield and nutrient content were not affected. In combined studies from 2018 and 2019 corn height was not impacted by biostimulant application but NDVI, photosynthetic efficiency, greenness and vigor were affected at different doses and corn growth stages. Only one treatment integrating HA + biofertilizer led to increased grain yield. In sum, these studies provided evidence that the individual and combined application of HA and biofertilizer can positively influence corn and cannabis growth most likely due to their plant biostimulant effects. However, the current study cannot conclusively affirm that the integrated use of HA and biofertilizers following the IPNS is a superior practice than the application of each compound individually and further studies should be conducted to validate these findings. / Doctor of Philosophy / The status of the corn (Zea mays L.) demand in Virginia and the Mid-Atlantic region is currently in deficit regarding the production in this area. This demand is exceeding supply by approximately 150%, then increasing feed grain yield and consequently production in the region can be simultaneously beneficial to crop farmers, end-users and the entire food supply chain. Furthermore, the consumer market is becoming more aware about sustainable practices for food production, which encourages producers to adopt agricultural practices that can minimize negative environmental impacts. This scenario enforces the scientific community's responsibility to test and develop environmental-friendly methods able to increase fertilization efficiency, decreasing the use in synthetic inputs but maintaining yield. The integrated plant nutrition system (IPNS) implements the combined and harmonious use of inorganic, organic and biological resources to take advantage of the potential synergetic effects. We conducted greenhouse studies and field experiments evaluating the effects of an IPNS on corn, and posteriorly based on the preliminary results obtained with corn, a greenhouse study addressing cannabis (Cannabis sativa L.) was also carried out. The greenhouse studies evaluated the effects of commercial synthetic fertilizer, humic acid (HA), compost/manure teas and bioinoculant as inorganic, organic and biological resources, respectively, and their synergy on corn and cannabis growth under a period of drought. Generally, for both studies, when comparing to the control values, the use of HA, biofertilizers and the integration of both compounds generated significantly greater early season plant height and photosynthesis measurements. The three-year field trial investigated the effects of nitrogen (N) fertilizer, HA, compost/manure teas and bioinoculant as inorganic, organic and biological resources, respectively and their synergy on corn growth. The individual and combined application of HA and biofertilizer generally influenced corn development, to varying degrees. In 2017, corn height, vegetation index, greenness and vigor were sensitive to the application of these biostimulants in different magnitudes and growth stages, however grain yield and nutrient content were not affected. In combined studies from 2018 and 2019 corn height was not impacted by biostimulant application but vegetation index, photosynthetic efficiency, greenness and vigor were affected at different doses and corn growth stages. Only one treatment combining HA + biofertilizer led to increased grain yield. In sum, these studies provided evidence that the individual and combined application of HA and biofertilizer can positively influence corn and cannabis growth most likely due their plant biostimulant effects. Even though, the current study cannot affirm that the combined use of HA and biofertilizers following the IPNS is a better practice than the application of each compound individually, this practice can be a more sustainable alternative to fit in the conventional farming scene.

Forests of the southeastern U.S. play an important role in meeting the increasing demand for forest products, and represent an important carbon (C) sink that can be managed as a potential tool for mitigating atmospheric CO2 concentrations and global climate change. However, realizing this potential depends on full accounting of the ecosystem carbon (C) budget. The separate evaluation of root-derived, autotrophic (RA) and microbially-derived heterotrophic (RH) soil respiration in response to management and climate change is important, as environmental and ecological factors often differentially affect these components, and RH can be weighed against net primary productivity (NPP) to estimate the C sink or source status of forest ecosystems. The objective of this research was to improve the quantitative and mechanistic understanding of soil respiratory fluxes in managed loblolly pine (Pinus taeda L.) plantations of the southeastern U.S. To achieve this overall objective, three studies were implemented to: 1) estimate the proportion and seasonality of RH:RS in four stand age classes, and identify relationships between RH:RS and stand characteristics 2) evaluate the effects of forest nutrient management and throughfall reduction on factors that influence RH and decomposition dynamics, including litter quality, microbial biomass, and enzyme activity and 3) evaluate the sensitivity of sources of RH (mineral soil-derived heterotrophic respiration; RHM, and leaf litter-derived heterotrophic respiration; RHL) to varying soil and litter water content over the course of a dry down event, and assess whether fertilization influences RH. Stand age and measurement season each had a significant effect on RH:RS (P < 0.001), but there were no interactive effects (P = 0.202). Mean RH:RS during the 12-month study declined with stand age, and were 0.82, 0.73, 0.59, and 0.50 for 3-year-old, 9-year-old, 18- year-old, and 25-year-old stands, respectively. Across all age classes, the winter season had the highest mean RH:RS of 0.85 while summer had the lowest of 0.55. Additionally, there were highly significant (P < 0.001) and strong (r > 0.5) correlations between RH:RS and peak LAI, stem volume, and understory biomass. Fertilization improved litter quality by significantly decreasing lignin:N and lignin:P ratios, caused a shift in extracellular enzyme activity from mineral soil N- and P-acquiring enzyme activity to litter C-acquiring enzyme activity, and increased microbial biomass pools. Throughfall reduction decreased litter quality by increasing lignin:N and lignin:P, but also increased C-acquiring enzyme activity. RHL was more sensitive to water content than RHM, and increased linearly with increasing litter water content (R2 = 0.89). The contribution of RHL to RH was greatest immediately following the wetting event, and decreased rapidly to near-zero between three – 10 days. RHM also had a strong relationship with soil water content (R2 = 0.62), but took between 200 – 233 days to attain near-zero RHM rates. Fertilization had no effect on RHM (P = 0.657), but significantly suppressed RHL rates after the wetting event (P < 0.009). This research provides estimates of RH:RS in managed loblolly pine systems that can be used to improve regional ecosystem C modeling efforts, and demonstrates the need to consider the impact of stand age and seasonal patterns to identify the point at which plantations switch from functioning as C sources to C sinks. Additionally, it demonstrates that the controls over RH are dynamic and influenced in the short-term by fertilization and changed precipitation regimes, with the greatest impact on properties affecting litter RH compared to mineral soil. Future research should work to improve the mechanistic understanding of the seasonal and spatial variability of RH and related controlling biotic and abiotic parameters to remedy the variability in existing RS and ecosystem C models. Understanding how management and climate change may impact factors that control RH will ultimately improve our understanding of what drives changes in forest C fluxes. / Ph. D.