The transformations of organic nitrogen to ammonium and nitrate are central processes in the internal soil nitrogen cycle. In most agricultural soils, ammonium is rapidly oxidized to nitrate in the process known as nitrification; often leading to loss of nitrate from the system. Nitrification is mediated by ammonia oxidizing bacteria or archaea, and nitrite oxidizing bacteria. Understanding links between process rates, enzyme activities and the communities of microbes that cycle nitrogen may contribute to sustainable management. Our main objective was to determine the impacts of contrasting nitrogen management on soil microbial communities, enzyme activities, and functional genes for nitrification and nitrogen mineralization in a Utah agricultural system. Process rates and activities were measured in laboratory potential assays and 15N isotope pool dilution experiments. The abundance and diversity of genes involved in nitrification and nitrogen mineralization were examined using quantitative real-time PCR, pyrosequencing, clone libraries, and metagenomics. Key enzymes and their relevant marker genes included ammonia monooxygenase (amoA), nitrite oxidoreductase (nxrB), protease (npr and sub), chitinase (chiA), and urease (ureC). The overall soil microbial community composition was assessed targeting ribosomal genes. Ammonia oxidizing bacteria were more responsive than archaea to ammonium fertilizers while the archaea were competitive under low ammonium levels. The relative contribution of ammonia oxidizing archaea to nitrification increased with increasing temperature and their activity had a higher temperature optimum than bacteria. The abundance of ammonia oxidizers in the organic farming system increased with organic nitrogen fertilizers and their activity was higher in manure than in compost treated soil. Nitrogen fertilizers strongly stimulated the rates of potential nitrite oxidation. Nitrospira was the only known nitrite oxidizer genus recovered from any soil sample. The application of organic nitrogen fertilizers, but not inorganic, increased the diversity of the prokaryotic community and the activities of soil enzymes. In the organic farming system, abundances of functional genes for mineralization were increased by organic nitrogen fertilizer and these abundances were significantly correlated with corresponding enzyme activity. Understanding the link between microbial communities and the biogeochemical functions of nitrification and mineralization may allow ecosystem models to incorporate microorganisms as dynamic components driving nitrogen flux.

Ammonia is a nuisance gas in many swine barns. The overall objective of this research project was to model ammonia formation and transmission processes in a grower-finisher swine barn, by first modelling the ammonia production and emission from urine puddles on the floor surface and the ammonia emission from the slurry pit, and then incorporating these emission rates in a dynamic model that separates the room and slurry pit headspace as two separate, but linked, control volumes. A series of studies were conducted to gather more information about the processes affecting the ammonia emission rate from the floor surface and the slurry that were later included in the overall room model developed. The model was then used to investigate ammonia reducing techniques and technologies based on the understanding of ammonia production and transmission incorporated in the model. The first step in modelling the ammonia emission rate from the floor surface was to determine the frequency of urinations by grower-finisher pigs. Male and female pigs were observed three times during their finishing phase to determine their urination frequency over the course of a day. The average measured urination frequency was 0.62 ± 0.11 urinations pig-1 h-1. A sinusoidal dromedary model was developed to describe the daily variation in urination frequency for male and female pigs between 51 and 78 kg.<p>In order for the deposited urinations on the floor surface to emit ammonia, the urea in the urine must first be converted to ammonia and the urease enzyme catalyzes this reaction. Two methods, a fixed-time-point method using the indophenol assay for ammonium-nitrogen analysis and a continuous method using the coupled enzyme assay, were used to measure enzyme activity at the floor surface of a swine barn and were compared to reported urease activity levels in the literature. Using both methods, there appeared to be an ammonia-producing site on the floor surface or within the collected samples that made accurate measurements of urease activity impossible. A review of urease activity levels in the literature from dairy-cow houses suggest that urease activity will be lowest following floor-cleaning and increase quickly following fouling of the floor surface. Based on the literature review, a urease activity value of 5 g NH¬3 m-2 h-1 was suggested for use in ammonia emission modelling of fouled floor surfaces in swine barns until better measurements become available. <p>The ammonia emissions from 36 simulated urine puddles under a variety of temperature, air velocity and initial urea concentration conditions were measured in a bench-scale experimental set-up. The measurements were used to calibrate and validate a dynamic, mechanistic, urine puddle emission model that considered the processes of evaporation, urea conversion, change in liquid concentration and puddle pH in order to simulate the amount of ammonia emitted from a puddle. Based on the correlation coefficients (R) between measured and simulated values for water volume (R=0.99), total ammoniacal nitrogen concentration (R=0.90), and total emission (R=1.00), along with five other statistical tests for each simulated variable, the model was deemed accurate. The measurements and simulations in this experiment showed the impact of puddle pH, urease activity and changing environmental conditions on the average puddle emission rate. Puddle emission continued to occur as long as there was still water.<p> The impact of different slurry compositions on the ammonia emission rate from slurry pits was tested in another bench-scale experimental set-up with emission chambers. The emission chamber concentration data collected was used to calibrate and validate a developed slurry emission model. The collected slurry samples were concentrated mixtures of urine and feces from individually-housed animals fed different diets. An empirical equation was developed to express the amount of total ammoniacal nitrogen in the slurry that was in the form of ammonia (f) and thus volatile to the surroundings. Based on the empirical equation, the simulated value of f was between 0.03 and 0.08 and did not show the sensitivity to slurry pH that has been reported by other authors. The slurry emission model with the empirical equation for f was validated with ammonia emission measurements from eight different slurry samples and simulated hourly concentration measurements within 17% and five-day average concentration measurements within 3%. Further testing was recommended to ensure the model developed for concentrated manure in this study was applicable to the more dilute slurry found in swine barns. <p>Using the information gained in the previous experiments, a mechanistic model describing the dynamic ammonia concentration in the room and in the slurry channel headspace of grower-finisher swine barns, as well as the ammonia emitted to the surrounding environment was developed. Data was collected from two grower-finisher rooms to use as input data to the model and for calibration and validation purposes. The model calibration procedure determined that the amount of emissions originating from the slurry for the simulated room conditions was generally less than 5% of the total room emissions, the air exchange rate through the slatted floor was approximately 4% of the room ventilation rate, and that in the first two weeks of animal activity in a room the urease activity at the floor surface will increase. The model was validated using separate data from that used in the calibration process. The model simulated hourly room concentration levels within 2.2 ppm and 3-day average concentration levels within 1.6 ppm. The model simulations were more accurate for one room that was fed a typical grower-finisher diet compared to another room fed an experimental diet with lower protein content and sugar-beet pulp inclusion. <p>The dynamic model was tested for its sensitivity to various input factors in terms of the floor emission rate, slurry emission rate and total emission rate. An interesting aspect of the simulations was that increases in either floor or surface emission rate were compensated to a small extent by decreases in the other emission rate as a result of a reduced concentration gradient for mass transfer. The ammonia emission rate from the floor was most sensitive to changes in urease activity, fouled floor area and puddle area. The ammonia emission rate from slurry was most sensitive to changes in slurry pH. The impact of input variables on the total emission rate was dependant on the simulated proportion of the total ammonia emission coming from either the floor surface or slurry channel. Three ammonia reduction techniques were tested and evaluated on their impact to the total ammonia emission rate from a room compared to a given set of control conditions.<p>The work in this thesis highlighted the importance of ammonia emission from the floor surface. The proportion of ammonia originating from the slurry and from the floor surface respectively will vary on the specific conditions within the barn, and will impact the effect of any ammonia mitigation technique that is investigated or used.

Investigation of soil bioactivity and weed infestation in spring oilseed rape agrocoenosis of different density Aušra Grybaitė Field experiments were carried out in 2004 and 2005 at the Experimental Station of Lithuanian University of Agriculture to study the influence of different spring oilseed rape (Brassica napus L.) ‘Sponsor’ densities (50.1-100, 100.1-150, 150.1-200, 200.1-250, 250.1-300, 300.1-350, 350.1-400, 400.1-450 plants m-2) on soil bioactivity and weed infestation. Soil - Calc(ar)i-Endohypogleyic Luvisol. By increasing of spring oilseed rape crop urease activity in the soil didn’t chage significantly. The saccharase activity in the rape agrocoenosis with density more than 150.1 plants m-2 significantly increased in comparison with saccharase activity in the thinest rape agrocoenosis. The content of humus (r = 0.73, P < 0.05) and available phosphorus (r = 0.71, P < 0.05) influenced the saccharase activity. Spring oilseed rape crop density had no influence on number of weed species, weed sprouts and weed density before harvest. Efficiency of weed suppressing increased when weed density in crop at 3-4 leaves stage increased. This proved the small similarity indexes of weed density in crop at 3-4 leaves stage and before harvest. Rape crop density had no influence on weed species change. Significant negative relationship was found between weed air-dry biomass and rape crop density (r = -0.82, P < 0.01). Most of weeds in rape crop were therophytes. Most of them... [to full text]

No description available.

Lignosulfonate (LS), a by-product of the pulp and paper industry, may have the potential to increase fertilizer N availability by acting as a urease and nitrification inhibitor. Four consecutive laboratory studies were conducted to evaluate the behavior of LS in agricultural soils. The effects of various types and rates of LS on soil respiration and soil N dynamics were determined. Effects of LS in combination with fertilizers on microbial activity and N dynamics were measured. Due to the high water solubility of LS a leaching column study was conducted to determine the potential leaching of LS. / Higher rates (20% w/w) of LS initially inhibited microbial activity. Generally LS was relatively resistant to degradation by soil microorganisms and small proportions of added LS-C ($<$2.1%) were leached from the soil columns, but leaching was a function of soil and moisture regime. Recovery of added mineral LS-N from soil treated with LS was low ($<$41%). Mineral N recovered from LS plus fertilizer amended soil was higher than recovery from corresponding fertilizer treatments. Lignosulfonate reduced urea hydrolysis and the proportion of added N volatilized as NH$ sb3$-N from a LS plus urea treatment. The mineral N pool from LS plus fertilizer treated soils had significantly lower NO$ sb3$-N concentrations than corresponding fertilizer treatments. Nitrification inhibition was believed to have been due to high fertilizer concentrations. At reduced urea and LS concentrations, LS decreased NO$ sb3$-N recovery in one of four soil types. However, reduced recovery may not have been from nitrification inhibition but possibly from denitrification or chemical reactions between N and phenolics from LS.

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e Matematicas / Made available in DSpace on 2012-10-17T00:34:51Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T21:46:35Z : No. of bitstreams: 1 108347.pdf: 3010279 bytes, checksum: 91da022de11cfa5e1d38e1cbf288ef18 (MD5) / Neste trabalho foi investigada a microencapsulação da urease na forma de extrato bruto (EE), através do método de coacervação salina, utilizando-se o sistema polimérico quitosana-PVA. A quitosana foi obtida a partir da quitina, que por sua vez foi extraída da casca do camarão e o EE foi extraído das sementes da Cucurbita pepo (abóbora). Os parâmetros do processo de microencapsulação tais como composição e pH da blenda, temperatura e tempo de coagulação, foram ajustados afim de maximizar a atividade enzimática. Através da comparação do perfil de pH, dependência de temperatura e constante de Michaelis-Menten, demonstrou-se que o uso do EE é uma alternativa em relação à utilização da urease padrão (EP). A microscopia eletrônica de varredura comprovou a encapsulação da urease. As determinações das atividades enzimáticas mostraram que a alta concentração salina, utilizada no processo de microencapsulação, não afetou a atividade da enzima. Os ensaios estatísticos mostraram que a enzima se distribui homogeneamente nas cápsulas durante o processo de microencapsulação e que há reprodutibilidade na determinação da atividade enzimática do EE. A urease microencapsulada mostrou uma reusabilidade de 23 vezes e a estabilidade do EE no processo de estocagem foi maior quando comparada com a EP. Ensaios in vitro mostraram que a determinação do teor de uréia em amostras de sangue e urina, usando-se a urease microencapsulada, são coerentes com os resultados obtidos a partir das mesmas amostras, através do método espectrofotométrico, realizado no Laboratório de Análises Clínicas do Hospital Universitário da UFSC.

AN ABSTRACT OF THE THESIS OF BRENT C. SUNDERLAGE, for the Master of Science degree in Plant, Soil, and Agricultural Systems, presented on March 8, 2017, at Southern Illinois University Carbondale. TITLE: LATE APPLICATION NITROGEN ON CORN IN SOUTHERN ILLINOIS AND SOIL PROPERTIES AFFECTING AMMONIA VOLATILIZATION FROM UREA FERTILIZER MAJOR PROFESSOR: Dr. Rachel L. Cook In corn (Zea mays L.) production systems, typical nitrogen fertilization occurs either before planting or after crop emergence, as late as the V6 stage. Since the majority of nitrogen uptake does not occur until V10 through R1, delaying nitrogen fertilization until V10 may reduce potential for early season soil N transformations and losses, while sustaining crop yields. A two-year study, conducted across three southern Illinois locations, evaluated the effects of various late sidedress nitrogen applications and enhanced efficiency fertilizers on corn yield and residual mineral soil N. The various nitrogen treatments compared: rates from 0-224 kg N ha-1; sources of urea and 32% UAN, with and without urease inhibitors 0.09% N-(n-butyl) thiophosphoric triamide (NBPT) as Agrotain® Ultra (AT) and 0.06% NBPT + 0.02% N-(n-propyl) thiophosphoric triamide (NPPT) as Limus® (L), and polymer-coated urea (ESN®); application timings at planting, V6, V10, and VT; placement either dribble applied, broadcasted, or injected. Across sites and years, late (V10) nitrogen split applications generally resulted in corn yields greater than or equal to the same total nitrogen rate applied at planting. Most late N treatment differences varied between sites and years, but 56 kg N ha-1 as broadcasted UAN at planting with 112 kg N ha-1 as broadcasted urea, either with or without AT or L at V10 were on average highest yielding treatments among sites in both years, with 16% greater yield than 168 kg N ha-1 as broadcasted UAN at planting. Urease inhibitors did not enhance yield in most instances, likely due to sufficient incorporating rainfall shortly after application. The effects of urease inhibitors used with late-application nitrogen on corn yield and actual ammonia volatilization remained ambiguous. Residual soil mineral nitrogen concentrations between 0-30 cm after harvest in the late nitrogen treatments did not elicit water quality concerns. Furthermore, ammonia volatilization from surface applied urea is controlled by many interrelated soil properties as well as environmental conditions. However, conclusions about the influence of soil properties on ammonia volatilization differ according to geographies and are not well established across a wide range of soil types. A laboratory soil incubation experiment measured the effects of soil properties on ammonia volatilization over 7 days from surface-applied urea and the efficacy of three urease inhibitors: Agrotain® Ultra (AT) as 0.09% NBPT, Limus® (L) as 0.06% NBPT + 0.02% NPPT, and NutriSphere-N® (NS) 30% calcium salt of maleic-itaconic copolymer among 83 soil surface samples from across the United States with a wide range of soil properties. The soil properties evaluated were: total exchange capacity, 1:1 CaCl2 pH, organic matter, buffering capacity, clay content, and urease activity. In Urea (R2 = 0.69) and Urea + NS (R2 = 0.62) models, total exchange capacity, clay, and buffering capacity significantly reduced ammonia volatilization, and organic matter significantly increased ammonia volatilization, while 1:1 CaCl2 pH and urease activity were non-significant. Clay, organic matter, and buffering capacity were correlated to total exchange capacity. Total exchange capacity was the strongest predictor and best consolidated variable to predict N loss of urea. In Urea + AT (R2 = 0.54) and Urea + L (R2 = 0.67) models, ammonia volatilization was significantly reduced at lower 1:1 CaCl2 pH and total exchange capacity, and all other soil properties were non-significant. The NBPT in Urea + AT and Urea + L likely decayed more rapidly under acidic soil conditions, resulting reduced NBPT efficacy and greater N loss at lower pH. Urea + AT and Urea + L reduced volatilization significantly by 18.2 percentage points compared to Urea or Urea + NS, and there were no significant differences between Urea + AT and Urea + L (α = 0.05). On average, NutriSphere-N® did not reduce volatilization.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-07-09T12:54:25Z No. of bitstreams: 1 THAÍS MARIA ALVES MARINHO - DISSERTAÇÃO (PPGCEMat) 2016.pdf: 4526314 bytes, checksum: 93577e66a4279c33e84cb662d3ce4735 (MD5) / Made available in DSpace on 2018-07-09T12:54:25Z (GMT). No. of bitstreams: 1 THAÍS MARIA ALVES MARINHO - DISSERTAÇÃO (PPGCEMat) 2016.pdf: 4526314 bytes, checksum: 93577e66a4279c33e84cb662d3ce4735 (MD5) Previous issue date: 2016-03-08 / Capes / Com o ascendente desenvolvimento de novas tecnologias, a procura por novos sistemas de sensoriamento vem aumentando, pois há uma necessidade de obter uma melhor precisão nos resultados de análises biológicas, com baixo custo e em tempo real, diante disso, os biossensores são dispositivos capazes de proporcionar esse tipo de resultado. Doenças ligadas a insuficiência renal necessitam desse tipo de precisão e rapidez, que é caracterizada pela concentração de ureia no sangue ou na urina, eliminado assim uma série de procedimentos laboratoriais. Logo, para montagem de um biossensor de ureia é preciso um biocomponente seletivo e específico, que possa identificar a ureia sem nenhuma interferência, como é o caso da enzima. A enzima capaz de catalisar a hidrolise de ureia é a uréase, formando como produto da reação o gás carbônico e a amônia. Para ser aplicado em um biossensor, a enzima precisa ser imobilizada, pois dessa forma confere uma maior estabilidade operacional e um maior armazenamento da mesma. Essa imobilização pode ser realizada por meio de polímeros. A quitosana é um polímero natural que vêm ganhando destaque para esta aplicação, diante de suas propriedades como baixo custo, abundância na natureza, fácil processamento, capacidade de formação membrana, entre outras. Diante do exposto, o objetivo desse trabalho é imobilizar a enzima urease utilizando como matriz a quitosana e quitosana/glutaraldeído, avaliando diferentes condições de preparação das membranas. As membranas foram depositadas sobre um transdutor que utilizou como suporte fitas de aço inox, eletrodepositadas com antimônio. Logo após, foram realizadas caracterizações por microscopia óptica (MO) e microscopia eletrônica de varredura (MEV), para avaliar as superfícies das membranas. Também, foram realizados testes de bioresposta dos eletrodos, para avaliar a efetividade da enzima imobilizada, através das respostas de sensibilidade, seletividade, estabilidade, tempo de resposta, faixa de linearidade, especificidade e repetibilidade dos biossensores. E foi observado que, a enzima imobilizada com quitosana e com adição do reticulante glutaraldeído, proporcionou melhores respostas, com mais estabilidade operacional e maior armazenamento da enzima, melhorando assim o tempo de vida da mesma. / With the upward development of new technologies, demand for new sensing systems is increasing because there is a need for better accuracy in the results of biological analyzes, with low cost and in real time, before that, the biosensors are devices capable of provide that kind of result. Diseases related to renal insufficiency require such precision and rapidity, which is characterized by the concentration of urea in blood or urine, thus eliminating a series of laboratory procedures. Therefore, for assembling a urea biosensor is needed a selective and specific bio-component that can identify the urea without any interference, as in the case of the enzyme. The enzyme capable of catalyzing the hydrolysis of urea is urease, forming a reaction product of carbon dioxide and ammonia. To be used in a biosensor, the enzyme must be immobilized, as this way confer greater operational stability and a longer storage thereof. This immobilization can be performed by means of polymers. Chitosan is a natural polymer that become increasingly more important for this application, on its properties such as low cost, abundance in nature, easy processing capacity of membrane formation, among others. Given the above, the objective of this work is to immobilize the enzyme urease as a matrix using chitosan and chitosan / glutaraldehyde, evaluating different conditions of preparation of membranes. Membranes were deposited on a transducer used as a support of stainless steel strips, electrodeposited with antimony. Soon after, characterizations were performed by optical microscopy (OM) and scanning electron microscopy (SEM) to evaluate the surfaces of the membranes. Also, the bioresponse electrode tests were performed to evaluate the effectiveness of the immobilized enzyme, through sensitivity responses, selectivity, stability, response time, linearity range, specificity and reproducibility of biosensors. It was observed that the immobilized enzyme with chitosan and crosslinking addition of glutaraldehyde gave the best responses with more operational stability and increased storage of the enzyme, thereby improving the lifetime thereof.

Orientador: Ely Nahas / Banca: Eliana Gertrudes Macedo Lemos / Banca: Eleonora Cano Carmona / Resumo: A expansão da citricultura tem sido feita em áreas de florestas e de pastagens. O efeito desta conversão de uma área de floresta tropical e de pastagem em laranjal (Citrus sinensis L. Osbeck) constitui uma oportunidade para avaliar mudanças nas variáveis microbiológicas e químicas do solo. As amostras de solo foram coletadas nas áreas de floresta, de pastagem e da parte alta (LA, laranjal do alto) e da baixada (LB, laranjal da baixada) de laranjal. As menores contagens de bactérias foram encontradas no solo sob pastagem e as maiores no solo sob floresta. O número de fungos foi significativamente (P < 0,05) maior no solo de laranjal do que nos demais solos. A atividade respiratória encontrada nos solos sob floresta e LB decresceu (P < 0,05) nos demais solos. Nenhuma variação foi observada na atividade nitrificante entre os solos estudados. As enzimas fosfatase e urease decresceram na seguinte ordem: floresta > pasto > LB > LA e diferença significativa apenas foi observada na atividade do solo sob floresta e LB. Diferenças (P < 0,05) foram constatadas no conteúdo da matéria orgânica entre o solo sob LA e o sob floresta e no da umidade do solo entre o solo sob LA e o sob LB. Em geral, os resultados encontrados sugerem que não houve mudança nas características microbiológicas e químicas entre o solo da floresta e do laranjal, porém estas variáveis foram diminuídas no solo sob pastagem em relação ao sob floresta. A adubação verde é a prática de cultivo e incorporação de plantas, produzidas no local ou adicionadas, com a finalidade de preservar e ou restaurar os teores de matéria orgânica e nutrientes dos solos, indo ao encontro da tendência mundial da busca de alimentos mais saudáveis, provenientes da agricultura orgânica ou produzidos com a mínima utilização de insumos químicos e degradação do meio ambiente...(Resumo completo, clicar no acesso eletrônico abaixo) / Abstract: The expansion of the citriculture has been made in forests and pasture areas. The effect of this conversion constitutes an opportunity to evaluate changes of tropical forest and pasture areas in orange grove (Citrus sinensis L.Osbeck) on the study of the soil microbiological and chemical variables. The samples had been collected in the areas of tropical forest, pasture and in the top (TOG) and bottom (BOG) of the orange grove. The lowest bacteria count was found in the pasture soil and the highest in the forest soil. The fungi number was significantly (P < 0.05) higher in the orange grove soil than in the other soils. Respiratory activity found in the forest and LB soils decreased (P <0.05) in the other soils. No change was observed in the nitrification activity among the studied soils. Phosphatase and urease activities decreased in the following order: forest > pasture > BOG > TOG and significant difference was only found in the activity of the forest and TOG soils. Differences (P <0.05) were found in the organic matter content among the TOG and the forest soils and in the moisture among of TOG and BOG soils. In general, the results found suggest that there was not change in the microbiological and chemical characteristic among forest and orange grove soils however these variables were decreased in the pasture soil in relation to the forest soil. The green fertilization is practical culture and the incorporation of plants that was produced in the place or added with the purpose to preserve and or to restore texts of organic matter and nutrients, going into worldwide trend of the food cultivation with more healthful, resulted from organic agricultura with the minimum use of chemical insumos and degradation of the environment. The objective of this study was to check the effect of to use three species plants cover, Crotalaria spectabilis (crotalária)...(Complete abstract, acess undermentioned eletronic) / Mestre

Made available in DSpace on 2014-06-11T19:27:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12-20Bitstream added on 2014-06-13T19:56:00Z : No. of bitstreams: 1 buzinaro_tn_me_jabo.pdf: 507442 bytes, checksum: a062b965b5c7aee4def0e6db053eb295 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A expansão da citricultura tem sido feita em áreas de florestas e de pastagens. O efeito desta conversão de uma área de floresta tropical e de pastagem em laranjal (Citrus sinensis L. Osbeck) constitui uma oportunidade para avaliar mudanças nas variáveis microbiológicas e químicas do solo. As amostras de solo foram coletadas nas áreas de floresta, de pastagem e da parte alta (LA, laranjal do alto) e da baixada (LB, laranjal da baixada) de laranjal. As menores contagens de bactérias foram encontradas no solo sob pastagem e as maiores no solo sob floresta. O número de fungos foi significativamente (P < 0,05) maior no solo de laranjal do que nos demais solos. A atividade respiratória encontrada nos solos sob floresta e LB decresceu (P < 0,05) nos demais solos. Nenhuma variação foi observada na atividade nitrificante entre os solos estudados. As enzimas fosfatase e urease decresceram na seguinte ordem: floresta > pasto > LB > LA e diferença significativa apenas foi observada na atividade do solo sob floresta e LB. Diferenças (P < 0,05) foram constatadas no conteúdo da matéria orgânica entre o solo sob LA e o sob floresta e no da umidade do solo entre o solo sob LA e o sob LB. Em geral, os resultados encontrados sugerem que não houve mudança nas características microbiológicas e químicas entre o solo da floresta e do laranjal, porém estas variáveis foram diminuídas no solo sob pastagem em relação ao sob floresta. A adubação verde é a prática de cultivo e incorporação de plantas, produzidas no local ou adicionadas, com a finalidade de preservar e ou restaurar os teores de matéria orgânica e nutrientes dos solos, indo ao encontro da tendência mundial da busca de alimentos mais saudáveis, provenientes da agricultura orgânica ou produzidos com a mínima utilização de insumos químicos e degradação do meio ambiente... / The expansion of the citriculture has been made in forests and pasture areas. The effect of this conversion constitutes an opportunity to evaluate changes of tropical forest and pasture areas in orange grove (Citrus sinensis L.Osbeck) on the study of the soil microbiological and chemical variables. The samples had been collected in the areas of tropical forest, pasture and in the top (TOG) and bottom (BOG) of the orange grove. The lowest bacteria count was found in the pasture soil and the highest in the forest soil. The fungi number was significantly (P < 0.05) higher in the orange grove soil than in the other soils. Respiratory activity found in the forest and LB soils decreased (P <0.05) in the other soils. No change was observed in the nitrification activity among the studied soils. Phosphatase and urease activities decreased in the following order: forest > pasture > BOG > TOG and significant difference was only found in the activity of the forest and TOG soils. Differences (P <0.05) were found in the organic matter content among the TOG and the forest soils and in the moisture among of TOG and BOG soils. In general, the results found suggest that there was not change in the microbiological and chemical characteristic among forest and orange grove soils however these variables were decreased in the pasture soil in relation to the forest soil. The green fertilization is practical culture and the incorporation of plants that was produced in the place or added with the purpose to preserve and or to restore texts of organic matter and nutrients, going into worldwide trend of the food cultivation with more healthful, resulted from organic agricultura with the minimum use of chemical insumos and degradation of the environment. The objective of this study was to check the effect of to use three species plants cover, Crotalaria spectabilis (crotalária)...(Complete abstract, acess undermentioned eletronic)