A pesquisa teve como objetivo contribuir para a sustentabilidade das formas de uso dos solos na Amazônia central, avaliando a influência da cobertura vegetal nos teores de nutrientes na solução do solo, ou seja, nos teores de cátions, ânions e carbono orgânico dissolvido (COD). Tomou-se como referência uma floresta primária, para comparação com áreas degradada, de reflorestamento, e de floresta secundária. O estudo foi realizado nos municípios de Manaus e Presidente Figueiredo, AM. Em cada área foram instalados extratores de tensão, nas profundidades de 10, 20, 50, 100 e 150 cm, para as coletas de solução de solo para análise da fase inorgânica, e nas profundidades 20 e 100 cm, para a fase orgânica. A coleta de solo para análise química foi realizada nas mesmas profundidades utilizadas para as coletas de solução do solo da fase inorgânica. As coletas de solução do solo e a quantificação da água da chuva foram realizadas ao longo de um ano hidrológico, seguindo a sazonalidade do clima regional, durante os anos de 2002 e 2003. Após a coleta, filtragem e preservação, as amostras foram encaminhadas ao laboratório para a determinação das concentrações de cátions e ânions por cromatografia líquida (Equipamento Dionex, modelo DX500). As concentrações de COD foram determinadas por combustão, com detecção do CO2 gerado nesta por infra vermelho não-dispersivo (Equipamento Shimadzu, modelo TOC 5000A). A maioria dos solos foi classificada como latossolos, muito ácidos, intemperizados e com baixa disponibilidade de nutrientes. Dos cátions presentes na solução do solo observou-se a predominância sódica-potássica, com grande influência dos aportes atmosféricos. Em relação aos ânions, a predominância foi de bicarbonato e cloreto, com grande contribuição da atividade biológica nas concentrações de bicarbonato em áreas cobertas por vegetação, e do aporte atmosférico nas concentrações de cloreto nas áreas sem cobertura vegetal. A vegetação apresentou forte influência na dinâmica dos íons, principalmente para nitrogênio, fósforo, potássio e magnésio, que apresentam como principal fontes a reciclagem da matéria orgânica e a transprecipitação. Na área degradada ocorreu predominância de cloreto e sódio, elementos que apresentam como principal fonte de entrada a precipitação. Na floresta secundária e no reflorestamento observou-se sinais de recuperação, com níveis mais elevados de nutrientes do que observado na área degradada, com destaque para aumentos significativos de COD e nitrato. Não somente a vegetação afetou a dinâmica dos íons avaliados, mas também a textura do solo, acidez, profundidade e precipitação. Para o carbono orgânico dissolvido observou-se enriquecimento à 100 cm de profundidade, provavelmente em função dos menores teores de ferro e alumínio em profundidade no solo. Este aumento em profundidade pode estar indicando uma ligação entre os sistemas terrestre e aquático, na qual o primeiro funciona como possível exportador de carbono para o segundo. / The main objective of this study was to contribute for the sustainability of land use in the central Amazon, evaluating the influence of vegetation cover on nutrient concentrations in soil solution that is, on the amounts of cations, anions and dissolved organic carbon (DOC). Using a primary forest as reference, we compared these concentrations with those in a degraded area, in a reforestation and also in a secondary forest. The study was conducted in the counties of Manaus and Presidente Figueiredo. In each site we collected soil solution using tension lysimeters installed at the depths of 10, 20, 50, 100 and 150 cm for the inorganic phase and at 20 and 100 cm for the analysis of the organic phase. The soil itself was also collected at the same depths used for the study of the inorganic phase of soil solution, to determine its structure and chemical composition. Soil solution and precipitation were collected during a hydrological year, following the regional climate seasonality in the years of 2002 and 2003. After sampling, filtering and preserving in the field, soil solution samples were sent to the laboratory for the determination of cation and anion concentrations by liquid chromatography (Dionex, DX500) and DOC concentrations in a total organic carbon analyzer (Shimadzu, TOC5000A). Most of the soils were classified as Oxisols, very acid, highly weathered and with low nutrient availability. Sodium and potassium were the most predominant cations in soil solution, due to the influence of the atmospheric inputs. For anions, bicarbonate and chloride were showed the highest concentrations. At the sites covered with vegetation, biological activity played an important role in bicarbonate concentrations, as opposed to the site without vegetation, in which chloride was predominant, due to atmospheric inputs. There was a good correlation between vegetation cover and the dynamics of nitrogen, phosphorus, potassium and magnesium, all of which have as the main source recycling of organic matter recycling and throughfall. At the degraded area, chloride and sodium predominated, due to their main source, which is the precipitation. At the secondary forest and the reforestation there are indicators of the recovery of pristine conditions, whit higher levels of nutrients than those of the degraded area, specially significant increases in DOC and nitrate concentrations. Not only the vegetation influenced the dynamics of these nutrients in soil solution, but also soil texture, acidity, soil depth and precipitation. DOC, for example, showed significant increases in concentrations at 1m depths, probably due to the lowest iron and aluminum concentrations at these soil depths. This increase of DOC with depth may indicate an important connection between terrestrial and aquatic ecosystem, with the acting as an exporter of C to the rivers of the region.

The sugarcane is a raw material which after industrialization originates derivatives, like sugar and alcohol, extremely important for the country economical income. The process of fermentation of the broth and posterior distillation originate alcohol and vinasse. The last was earlier considered as a pollutant, however, nowadays it is carefully used for the improvement of biological, physical and chemical properties of the soil. The present work aims to evaluating, in laboratory, the modifications and displacements of some physical and chemical attributes in two clayish soils that had received vinasse for more than 25 years, in the factories Marituba (UMA) and Sto Antonio (USA), in the sugar cane region of Alagoas state, Brazil. The soil samples were collected in five layers (0-10, 10-20, 20-40, 40-70 and 70-100 cm) of depth, using the factorial [(2) plant (2) +vinasse (+v)/ -vinasse (-v) - (5) layers], 22x5 totalizing twenty treatments with four repetitions. From the results, it was noticed that vinasse promoted significant alterations in the soil, in accordance with the variance analysis (ANAVA), for with 0,01 of probability for test F, the attributes: pH, P, K+, Ca2++Mg2+, Total Organic Matter in Soil (OMS), Water Soluble Carbon (WSC), Potassium Saturation in the Cation Exchange Capacity (CEC) and porosity, The variables Soil Density (SD) and clay had presented significant differences, 0,05 level of probability and sands had been non-significant (NS). For the changeable layers in the profile of the ground, the parameters that had significance in 1% were; pH, P, K+, Ca2++Mg2+, OMS, WSC, CEC, sands and porosity, while the variable CEC and SD had been non-significant (NS). In the interaction of vinasse with layers the parameters that had significant differences for F test 0,01 were P, K+, Ca2++Mg2+, MOS, CTC, DS, % K+ CTC and sands, with significant difference of 0,05 for pH, CSA and clay. In the interaction of vinasse with layers, the differences 0,01 had been for P, Ca2++Mg2+, OMS, WCS, and % K+ CTC, of 0,05 of probability, the variables CTC and DS presented significant differences, already pH, K+, CEC, sands, clay and porosity had been NS. Comparing the averages among areas with and without vinasse, for the test of Tukey 0,05, have average higher for layers of the area that received vinasse: pH, P, K+, Ca2++Mg2+, WCS, SD and % K+ CTC. They had been similar for CEC and sands, however, in the area that did not receive vinasse, OMS, clay and porosity had presented higher values. The data obtained in this study indicate that the addition of vinasse was beneficial to the soil and therefore it is recommended to maintain its use, on the comparison between the benefit and the damage it can cause stillage. / A cana-de-açúcar é a matéria prima que depois de industrializada origina vários derivados, tendo como principais o açúcar e o álcool. Após o processo de fermentação do caldo e posterior destilação, originam-se o álcool e a vinhaça. Essa, que antes era considerada poluente, atualmente é utilizada, com zelo, para a melhoria das propriedades biológicas, físicas e químicas do solo. O presente trabalho visou avaliar, em laboratório, as modificações e deslocamentos de alguns atributos físicos e químicos em dois Argissolos que recebem vinhaça há mais de 25 anos, nas usinas Marituba (UMA) e Sto Antonio (USA), localizadas na região canavieira de Alagoas, Brasil. Foram utilizadas amostras de solos coletadas em cinco camadas (0-10, 10-20, 20-40, 40-70 e 70-100 cm) do perfil do solo, em que se aplicou o fatorial 22x5 [(2)usinas-(2) com vinhaça (CV) e sem vinhaça (SV)-(5)camadas], totalizando vinte tratamentos com quatro repetições. Pelos resultados, se observou que a vinhaça promoveu alterações significativas no solo. Os atributos: pH, P, K+, Ca2++Mg2+, Matéria Orgânica do Solo (MOS), Carbono Solúvel em Água (CSA), percentagem de potássio trocável na capacidade de troca de cátions em (%KCTC) e porosidade apresentaram diferenças significativas a 0,01 de probabilidade pelo teste F. As variáveis, densidade do solo (DS) e argila, apresentaram diferenças significativas a 0,05 de probabilidade e capacidade de troca de cátions (CTC) e areias foram não significativas (NS). Para as variáveis do solo houve significância a 0,01 para: pH, P, K+, Ca2++Mg2+, MOS, CSA, CTC, areias e porosidade, enquanto as variáveis % K+ CTC e DS foram NS. Na interação de vinhaça com camadas, houve diferenças significativas pelo teste F a 0,01 para P, K+, Ca2++Mg2+, MOS, CTC, DS, % K+ CTC e areias. Houve diferença significativa a 0,05 para pH, CSA e argila. Na interação de vinhaça com camadas, as diferenças a 0,01 foram para P, Ca2++Mg2+, MOS, CSA, e % K+ CTC, com 0,05 de probabilidade, as variáveis CTC e DS apresentaram diferenças significativas, já pH, K+, CTC, areia, argila e porosidade foram NS. Comparando as médias entre as áreas com e sem vinhaça, pelo teste de Tukey a 0,05, tem-se médias maiores para camadas da área que receberam vinhaça, para pH, P, K+, Ca2++Mg2+, CSA, DS e % K+ CTC. Foram semelhantes para CTC e areias, porém, na área que não recebeu vinhaça apresentaram superioridade: MOS, argila e porosidade. Os dados obtidos no presente trabalho indicam que a adição de vinhaça ao solo foi benéfica e por isso se recomenda a manutenção de seu uso, diante da comparação entre o benefício e o prejuízo que a vinhaça poderá causar.

<p>Methane (CH₄) is the second most powerful greenhouse gas (GHG) behind carbon dioxide (CO₂), and is able to trap a large amount of long-wave radiation, leading to surface warming. Carbon monoxide (CO) plays an important role in controlling the oxidizing capacity of the atmosphere by reacting with OH radicals that affect atmospheric CH₄ dynamics. Terrestrial ecosystems play an important role in determining the amount of these gases into the atmosphere. However, global quantifications of CH₄ emissions from wetlands and its sinks from uplands, and CO exchanges between land and the atmosphere are still fraught with large uncertainties, presenting a big challenge to interpret complex atmospheric CH₄ dynamics in recent decades. In this dissertation, I apply modeling approaches to estimate the global CH₄ and CO exchanges between land ecosystems and the atmosphere and analyze how they respond to contemporary and future climate change.</p> <p>Firstly, I develop a process-based biogeochemistry model embedded in Terrestrial Ecosystem Model (TEM) to quantify the CO exchange between soils and the atmosphere at the global scale (Chapter 2). Parameterizations were conducted by using the CO <i>in situ</i> data for eleven representative ecosystem types. The model is then extrapolated to global terrestrial ecosystems. Globally soils act as a sink of atmospheric CO. Areas near the equator, Eastern US, Europe and eastern Asia will be the largest sink regions due to their optimum soil moisture and high temperature. The annual global soil net flux of atmospheric CO is primarily controlled by air temperature, soil temperature, SOC and atmospheric CO concentrations, while its monthly variation is mainly determined by air temperature, precipitation, soil temperature and soil moisture. </p> <p>Secondly, to better quantify the global CH₄ emissions from wetlands and their uncertainties, I revise, parameterize and verify a process-based biogeochemical model for methane for various wetland ecosystems (Chapter 3). The model is then extrapolated to the global scale to quantify the uncertainty induced from four different types of uncertainty sources including parameterization, wetland type distribution, wetland area distribution and meteorological input. Spatially, the northeast US and Amazon are two hotspots of CH₄ emissions, while consumption hotspots are in the eastern US and eastern China. The relationships between both wetland emissions and upland consumption and El Niño and La Niña events are analyzed. This study highlights the need for more in situ methane flux data, more accurate wetland type and area distribution information to better constrain the model uncertainty.</p> <p>Thirdly, to further constrain the global wetland CH₄ emissions, I develop a predictive model of CH₄ emissions using an artificial neural network (ANN) approach and available field observations of CH₄ fluxes (Chapter 4). Eleven explanatory variables including three transient climate variables (precipitation, air temperature and solar radiation) and eight static soil property variables are considered in developing the ANN models. The models are then extrapolated to the global scale to estimate monthly CH₄ emissions from 1979 to 2099. Significant interannual and seasonal variations of wetland CH₄ emissions exist in the past four decades, and the emissions in this period are most sensitive to variations in solar radiation and air temperature. This study reduced the uncertainty in global CH₄ emissions from wetlands and called for better characterizing variations of wetland areas and water table position and more long-term observations of CH₄ fluxes in tropical regions.</p> <p>Finally, in order to study a new pathway of CH₄ emissions from palm tree stem, I develop a two-dimensional diffusion model. The model is optimized using field data of methane emissions from palm tree stems (Chapter 5). The model is then extrapolated to Pastaza-Marañón foreland basin (PMFB) in Peru by using a process-based biogeochemical model. To our knowledge, this is among the first efforts to quantify regional CH₄ emissions through this pathway. The estimates can be improved by considering the effects of changes in temperature, precipitation and radiation and using long-period continuous flux observations. Regional and global estimates of CH₄ emissions through this pathway can be further constrained using more accurate palm swamp classification and spatial distribution data of palm trees at the global scale.</p>

<p>This thesis is a collection of three research articles to quantify carbon fluxes and isotopic signature changes across global terrestrial ecosystems. Chapter 2, the first article of this thesis, focuses on the importance of an under-estimated methane soil sink for contemporary and future methane budgets in the pan-Arctic region. Methane emissions from organic-rich soils in the Arctic have been extensively studied due to their potential to increase the atmospheric methane burden as permafrost thaws. However, this methane source might have been overestimated without considering high affinity methanotrophs (HAM, methane oxidizing bacteria) recently identified in Arctic mineral soils. From this study, we find that HAM dynamics double the upland methane sink (~5.5 TgCH₄yr^-1) north of 50°N in simulations from 2000 to 2016 by integrating the dynamics of HAM and methanogens into a biogeochemistry model that includes permafrost soil organic carbon (SOC) dynamics. The increase is equivalent to at least half of the difference in net methane emissions estimated between process-based models and observation-based inversions, and the revised estimates better match site-level and regional observations. The new model projects double wetland methane emissions between 2017-2100 due to more accessible permafrost carbon. However, most of the increase in wetland emissions is offset by a concordant increase in the upland sink, leading to only an 18% increase in net methane emission (from 29 to 35 TgCH₄yr^-1). The projected net methane emissions may decrease further due to different physiological responses between HAM and methanogens in response to increasing temperature. This article was published in <i>Nature Climate Change</i> in March 2020.</p> <p>In Chapter 3, the second article of this thesis, I develop and validate the first biogeochemistry model to simulate carbon isotopic signatures (δ¹³C) of methane emitted from global wetlands, and examined the importance of the wetland carbon isotope map for studying the global methane cycle. I incorporated a carbon isotope-enabled module into an extant biogeochemistry model to mechanistically simulate the spatial and temporal variability of global wetland δ¹³C-CH₄. The new model explicitly considers isotopic fractionation during methane production, oxidation, and transport processes. I estimate a mean global wetland δ¹³C-CH₄ of -60.78‰ with its seasonal and inter-annual variability. I find that the new model matches field chamber observations 35% better in terms of root mean square estimates compared to an empirical static wetland δ¹³C-CH₄ map. The model also reasonably reproduces the regional heterogeneity of wetland δ¹³C-CH₄ in Alaska, consistent with vertical profiles of δ¹³C-CH₄ from NOAA aircraft measurements. Furthermore, I show that the latitudinal gradient of atmospheric δ¹³C-CH₄ simulated by a chemical transport model using the new wetland δ¹³C-CH₄ map reproduces the observed latitudinal gradient based on NOAA/INSTAAR global flask-air measurements. I believe this study is the first process-based biogeochemistry model to map the global distribution of wetland δ¹³C-CH₄, which will significantly help atmospheric chemistry transport models partition global methane emissions. This article is in preparation for submission to <i>Nature Geoscience</i>.</p> <p>Chapter 4 of this thesis, the third article, investigates the importance of leaf carbon allocation for seasonal leaf carbon isotopic signature changes and water use efficiency in temperate forests. Temperate deciduous trees remobilize stored carbon early in the growing season to produce new leaves and xylem vessels. The use of remobilized carbon for building leaf tissue dampens the link between environmental stomatal response and inferred intrinsic water use efficiency (iWUE) using leaf carbon isotopic signatures (δ¹³C). So far, few studies consider carbon allocation processes in interpreting leaf δ¹³C signals. To understand effects of carbon allocation on δ¹³C and iWUE estimates, we analyzed and modeled the seasonal leaf δ¹³C of four temperate deciduous species (<i>Acer saccharum, Liriodendron tulipifera, Sassafras albidum, </i>and <i>Quercus alba</i>) and compared the iWUE estimates from different methods, species, and drought conditions. At the start of the growing season, leaf δ¹³C values were more enriched, due to remobilized carbon during leaf-out. The bias towards enriched leaf δ¹³C values explains the higher iWUE from leaf isotopic methods compared with iWUE from leaf gas exchange measurements. I further showed that the discrepancy of iWUE estimates between methods may be species-specific and drought sensitive. The use of δ¹³C of plant tissues as a proxy for stomatal response to environmental processes, through iWUE, is complicated due to carbon allocation and care must be taken when interpreting estimates to avoid proxy bias. This article is in review for publication in <i>New Phytologist</i>.</p> <p> </p>

No description available.

Biogas im Rahmen einer nachhaltigen Landwirtschaft zu erzeugen bedeutet u. a., die anfallenden Gärprodukte als Dünger zu verwenden, um die Verluste im Nährstoffkreislauf zu minimieren. Die vorliegende Arbeit geht der Frage nach, welche Wirkungen Gärprodukte aus der Biogasproduktion bei der Verwendung als Dünger auf Boden und Pflanzen haben. Die Ergebnisse von Parzellenfeld- und Praxisversuchen, in denen Gärprodukte aus der Mono- und Kofermentation von Energiepflanzen im Vergleich zu N-Mineraldünger untersucht wurden, werden vorgestellt und diskutiert. Zur Beurteilung der Wirkungen auf den Boden wurden bodenchemische und bodenbiologische Parameter herangezogen sowie die Abbaustabilität der organischen Substanz der Gärprodukte gemessen. Zur Untersuchung der Wirkungen auf die Pflanzen wurden verschiedene Wachstums-, Entwicklungs-, Ertrags- und Qualitätsparameter erfasst und ausgewertet. Die Gärprodukte zeichnen sich durch relativ hohe Ammoniumgehalte sowie durch hohe pH-Werte aus. Das Pflanzenwachstum und die Erträge werden durch die Düngung mit Gärprodukten gesteigert, wobei die Wirkung trotz der hohen Ammoniumgehalte deutlich hinter denen des N-Mineraldüngers zurückbleibt. Die berechneten Nährstoffbilanzen weisen auf deutliche Unterschiede zwischen den untersuchten Gärprodukten und Kulturarten, aber auch zwischen den beiden Versuchsjahren hin. Die Ergebnisse zeigen jedoch, dass durch die Verwendung von Gärprodukten als Dünger wichtige Pflanzennährstoffe rezykliert werden können, wodurch der Einsatz von Mineraldüngern reduziert werden kann. Hinsichtlich der Wirkungen von Gärprodukten auf den Boden zeichnen die umfangreichen Analysen ein differenziertes Bild. Die mikrobiologischen Umsetzungsprozesse im Boden werden insbesondere in den ersten Tagen nach der Ausbringung gefördert. Weiterer Forschungsbedarf wird insbesondere hinsichtlich der Wirkungen auf die Bodenmakrofauna aufgezeigt. / Producing biogas in a sustainable agricultural system means using digestates as fertilizers, in order to minimize leaks in nutrient cycles. The aim of this work is to investigate effects on soil and plants after field application of digestates. In this respect, results from plot- and practical fieldexperiments are analyzed to compare digestates from mono- and from co-fermentation of energy crops in comparison to mineral N-fertilizer. Soil chemical and biological effects were assessed on the basis of selected parameters, one of which was the stability of the organic matter applied. Effects on crops have been evaluated by measuring growth, development, yields, and quality of the crops. The digestates have been analyzed and showed especially high amounts of ammonium and a high pH-value. Plant growth and yields increased as a result of fertilization. However, despite high amounts of ammonia present in digestates, fertilizing effects have been much lower compared to mineral N-fertilization. The calculated nutrient balances showed obvious differences between the digestates analyzed, crops, and also between the two experimental years. Generally, the results demonstrate that nutrients can be recycled by using digestates as fertilizers and thus the use of mineral fertilizers can be reduced. The extensive soil analyses presented in this work show diverse results. Microbial metabolic processes in the soil are increased especially during the first few days after digestate application. More research is needed with respect to effects on macro fauna.

O principal objetivo deste estudo foi avaliar a saúde da microbacia hidrográfica do rio Passo Cue, região oeste do estado do Paraná, por meio do uso de indicadores de qualidade de solo e água. Esse rio é afluente da margem esquerda do reservatório de Itaipu e pertence à bacia hidrográfica do Paraná III. Como indicadores de qualidade de água foram utilizadas variáveis físicas, químicas e biológicas. Para avaliação da qualidade do solo, foram analisados os atributos textura, densidade, porosidade, carbono orgânico, biomassa microbiana, respiração basal, quocientes metabólico e microbiano, macro e micronutrientes, pH e saturação por alumínio. Os indicadores que se mostraram mais eficientes foram a densidade do solo e o quociente metabólico. O solo sob plantio direto apresentou melhor qualidade física, química e biológica em relação ao cultivo mínimo sem rotação de culturas. O solo sob plantio direto apresentou melhor qualidade biológica do que o solo sob fragmento florestal. A qualidade da água na microbacia do rio Passo Cue piorou da montante para a jusante em função do seu uso agropecuário. / The main purpose of this study was to evaluate the conditions of the Passo Cue river watershed, in western Paraná, through soil and water quality indicators. The river is an affluent of the left bank of the Itaipú reservoir and is a part of the Paraná III watershed. Physical, chemical and biological variables were used as water quality indicators. To evaluate the soil quality, texture, density, porosity, organic carbon, microbial biomass, basal respiration, metabolic and microbial quotients, macro and micronutrients, pH and aluminum saturation were analyzed. The more efficient indicators were soil density and metabolic quotient. No-tillage soil showed better physical, chemical and biological quality in relationship with the minimum tillage one with no crop rotation. The soil under no tillage had better biological quality than under forest fragment. The water quality of the Passo Cue river worsened downstream in view of the agricultural use.

O principal objetivo deste estudo foi avaliar a saúde da microbacia hidrográfica do rio Passo Cue, região oeste do estado do Paraná, por meio do uso de indicadores de qualidade de solo e água. Esse rio é afluente da margem esquerda do reservatório de Itaipu e pertence à bacia hidrográfica do Paraná III. Como indicadores de qualidade de água foram utilizadas variáveis físicas, químicas e biológicas. Para avaliação da qualidade do solo, foram analisados os atributos textura, densidade, porosidade, carbono orgânico, biomassa microbiana, respiração basal, quocientes metabólico e microbiano, macro e micronutrientes, pH e saturação por alumínio. Os indicadores que se mostraram mais eficientes foram a densidade do solo e o quociente metabólico. O solo sob plantio direto apresentou melhor qualidade física, química e biológica em relação ao cultivo mínimo sem rotação de culturas. O solo sob plantio direto apresentou melhor qualidade biológica do que o solo sob fragmento florestal. A qualidade da água na microbacia do rio Passo Cue piorou da montante para a jusante em função do seu uso agropecuário. / The main purpose of this study was to evaluate the conditions of the Passo Cue river watershed, in western Paraná, through soil and water quality indicators. The river is an affluent of the left bank of the Itaipú reservoir and is a part of the Paraná III watershed. Physical, chemical and biological variables were used as water quality indicators. To evaluate the soil quality, texture, density, porosity, organic carbon, microbial biomass, basal respiration, metabolic and microbial quotients, macro and micronutrients, pH and aluminum saturation were analyzed. The more efficient indicators were soil density and metabolic quotient. No-tillage soil showed better physical, chemical and biological quality in relationship with the minimum tillage one with no crop rotation. The soil under no tillage had better biological quality than under forest fragment. The water quality of the Passo Cue river worsened downstream in view of the agricultural use.

The fate and behaviour of estrogens in the environment are of concern due to the compounds’ endocrine disruption potential. Estrogens, namely 17β-estradiol (E2), estrone (E1), and estrogen sulphates, i.e. 17β-estradiol-3-sulphate (E2-3S) and estrone-3-sulphate (E1-3S) excreted by livestock constitute a potential source for estrogen contamination in the environment. A method was developed to separate and quantify the hormones by high-performance-liquid-chromatography (HPLC) and ultraviolet detection (UV). A combination of dichloromethane (DCM) and dicyclohexylamine hydrochloride (DCH·HCl) gave recoveries from 97.3 to 107% for E1-3S extraction from aqueous solutions. The recoveries from soil samples ranged from 80.9 to 95.2% (E2-3S), and from 86.3 to 91.7% (E1-3S), respectively. Results of batch sorption studies showed that Freundlich isotherms were nonlinear (N ≠ 1) with Kf values ranging from 34.2 to 57.2, and from 3.42 to 4.18 mg¹-N LN kg⁻¹ for E1, and E1-3S, respectively, indicating the sorption affinity of E1-3S was about an order of magnitude lower than that of E1. The hydrophilic sulphate group of E1-3S possibly shielded the compound from hydrophobic interactions with the soil organic matter and allophanic clay minerals that were proposed as sorbents for E1. Contraction of clay minerals, “salting out” and competitive sorption of artificial urine constituents were likely to have been responsible for observed changes in Freundlich parameters when artificial urine was used as mediator matrix. Plotting the effective distribution coefficient as a function of hypothetical exposure concentrations facilitated the comparison of the sorption behaviour of both compounds as influenced by the mediator solution. The results emphasized that using the CaCl₂ matrix might result in false inferences for the sorption behaviour of these compounds in a dairying environment. The four hormones rapidly degraded in the agricultural soils under aerobic conditions, and the majority of the compounds degraded > 50% within the first 24 hrs. Soil arylsulphatase activities were directly correlated with degradation rate constants of the estrogen sulphates. Estrone was identified as a metabolite of E2 and E1-3S, and these three compounds were observed as metabolites of E2-3S. Single-first order (SFO) and double first-order in parallel (DFOP) kinetics were used to model the degradation and metabolite formation data. The results showed that the DFOP model was in most cases better able to predict the parent compound degradation than the SFO model, and also enabled to estimate accurate degradation endpoints. ER-CALUX® analysis revealed the formation of estrogenicity during E2-3S degradation, which could partly be explained by the formation of the metabolites E2 and E1. Transport studies with E1-3S and E1 showed that the transport and retention of both compounds were significantly influenced by the mediator matrix. While no breakthrough curves (BTCs) were recorded during hormone application in CaCl₂ (10 mM) both hormones were detected in the leachate when applied in artificial urine. Rate-limited sorption processes were proposed for the delayed arrival of the hormone BTCs compared with a conservative bromide tracer. Intense colouration of the leachate during the artificial urine experiments suggested the hormones were likely to be moved by colloid-facilitated transport. Furthermore, the detection of residue hormone and metabolite concentrations implied that degradation of E1-3S and E1 was hampered by urine constituents such as glycine and urea.

New Zealand’s 5.3 million strong dairy herd returns approximately 106 million litres of urine to pasture soils daily. The urea in that urine is rapidly hydrolysed to ammonium (NH₄⁺), which is then nitrified, with denitrification of nitrate (NO₃⁻) ensuing. Nitrous oxide (N₂O), a potent greenhouse gas (GHG), is produced via nitrification and denitrification, which are enzyme-catalysed processes mediated by soil microbes. Thus microbes are linked intrinsically to urine patch chemistry. However, few previous studies have investigated microbial dynamics in urine patches. Therefore the objective of these four experiments was to investigate the effects on soil microbial communities of cow urine deposition. Methods used included phospholipid fatty acid (PLFA) analyses of microbial community structure and microbial stress, dehydrogenase activity (DHA) assays measuring microbial activity, and headspace gas sampling of N₂O, ammonia (NH₃) and carbon dioxide (CO₂) fluxes. Experiment 1, a laboratory study, examined the influence of soil moisture and urinary salt content on the microbial community. Both urine application and high soil moisture increased microbial stress, as evidenced by significant changes in PLFA trans/cis and iso/anteiso ratios. Total PLFAs and DHA showed a short-term (< 1 week) stimulatory effect on microbes after urine application. Mean cumulative N₂O-N fluxes were 2.75% and 0.05% of the nitrogen (N) applied, from the wet (70% WFPS) and dry (35% WFPS) soils, respectively. Experiment 2, a field trial, investigated nutrient dynamics and microbial stress with plants present. Concentrations of the micronutrients, copper, iron and molybdenum, increased up to 20-fold after urine application, while soil phosphorus (P) concentrations decreased from 0.87 mg kg ⁻¹ to 0.48 mg kg⁻¹. Plant P was also lower in urine patches, but total PLFAs were higher, suggesting that microbes had utilised the available nutrients. Microbial stress again resulted from urine application but, in contrast to experiment 1, the fungal biomass recovered after its initial inhibition. Studies published during the course of this thesis reported that hippuric acid (HA) and its hydrolysis product benzoic acid (BA) significantly reduced N₂O-N emissions from synthetic cow urine, thus experiment 3 investigated this effect using real cow urine. Cumulative N₂O-N fluxes were 16.8, 5.9 and 4.7% of N applied for urine (U) alone, U+HA and U+BA, respectively. Since NH₃-N volatilisation remained unchanged, net gaseous N emissions were reduced. Trends in total PLFAs and microbial stress were comparable to experiment 1 results. Experiment 4 studied HA effects at different temperatures and found no inhibition of N₂O-N fluxes from HA-amended urine. However, mean cumulative N₂O-N fluxes were reduced from 7.6% of N applied at 15–20°C to 0.2% at 5–10°C. Total cumulative N emissions (N₂O-N + NH₃-N) were highest at 20°C (17.5% of N applied) and lowest at 10°C (9.8% of N applied). Microbial activity, measured as potential DHA, increased with increasing temperature. This work has clearly shown that the stimulation and inhibition of the soil microbial community by urine application are closely linked to soil chemistry and have significant impacts not only on soil nutrient dynamics but also on N₂O-N emissions and their possible mitigation.