The thicketization of the semi-arid region of the United States has resulted in a dramatic change allowing invasive woody species to dominate the landscape with an unknown impact to the water budget. This landscape transformation has created a need to study the hydrology of the region and in particular the effects of increased brush on the water cycle. To study the effects of invasive brush on the water budget, a portable abovecanopy rainfall simulator was developed for plot scale hydrologic research. The rainfall simulator was tested at various field locations, including within the Edwards Plateau, to replicate natural rainfall events on typical hillslope-scale plots. The rainfall simulator was used to quantify aspects of the water budget for a 7 m by 14 m research plot on the Edwards Plateau in Texas. Three rainfall simulation dates were selected for detailed hydrologic analysis. Overall, throughfall accounted for 74% of the water applied to the plot, while 26% of applied water was in the form of stemflow. Lateral subsurface flow represented 33% of the water measured leaving the research plot. A notable result of rainfall simulations was extensive lateral subsurface flow and no surface runoff. The rainfall simulator has proven to be a cost-effective and efficient research tool for replicating natural rainfall in arid and semi-arid environments.

A canavicultura é de extrema importância para o Brasil e para o mundo. O aumento da produção de cana-de-açúcar reflete em maior uso de herbicidas, como o diuron e a hexazinona. A adoção do sistema de cana crua, em que a palha permanece sobre o solo após colheita mecanizada, implica em alteração na dinâmica ambiental destes herbicidas. Portanto, o objetivo deste trabalho foi avaliar as perdas de diuron e hexazinona por escoamento superficial em sistemas de cana crua. O experimento constou de sistema fatorial 3x2x2 (12 tratamentos) com delineamento em blocos casualizados e 4 repetições, totalizando 48 parcelas. Os fatores foram: 3 níveis de palha (0, 50% e 100% da dose = 14 t ha-1); 2 níveis de umidade de solo (10 e 18% v/v) e 2 momentos de chuva (0 e 3 dias após aplicação dos produtos). Sobre as parcelas de 1 m2, foi utilizado um simulador de chuvas ajustado para evento com intensidade de 80 mm h-1 durante uma hora e meia, resultando num volume total precipitado de 120 mm. Um produto comercial contendo diuron e hexazinona foi aplicado na dose de 3 kg ha-1 e calda de 700 L ha-1, conforme recomendações do fabricante. As quantidades de água e sedimentos escoadas foram registradas e as concentrações dos herbicidas analisadas em solução por UPLC. Os resultados foram submetidos à ANOVA e, em caso de interação, as médias foram comparadas pelo teste de Tukey (p<0,05). A quantidade de diuron e hexazinona nos sedimentos foi estimada fazendo uso dos dados de sorção da literatura. A presença de palha sobre o solo reduziu as perdas de água, sedimentos e diuron, mas não teve efeitos sobre as perdas de hexazinona. Em outras palavras, a cobertura morta não reduz as perdas de moléculas muito solúveis, como a hexazinona. As maiores perdas de diuron e hexazinona foram observadas em solução, mesmo no tratamento controle (sem palha), uma vez que a palha reduz a massa de sedimentos desprendida. No entanto, não houve diferença nas perdas entre os dois níveis de palha (50 e 100%), sugerindo que 7 t ha-1 são suficientes para atenuar as perdas de água, sedimentos e diuron. Maiores teores de água no solo (18 versus 10% v/v) implicaram em maiores perdas dos herbicidas por escoamento superficial. Já o momento da chuva não afetou as perdas dos herbicidas, indicando que 3 dias não foram suficientes para a dissipação ou maior sorção dessas moléculas. / Sugarcane is a major crop in Brazil and of great importance to the world. Higher yields implicate in higher use of pesticides, such as diuron and hexazinone. The adoption of green cane system, in which the straw is kept in the soil surface after mechanical harvesting, has changed the environmental behavior of theses herbicides. Therefore, the goal of this research was to evaluate runoff losses of diuron and hexazinone in green cane systems. The 3x2x2 (12 treatments) factorial experiment was performed in a randomized block with 4 replicates. The factors were i) 3 levels of sugarcane straw (0, 50% and 100%, based on a dose of 14 t ha-1); ii) 2 levels of initial soil moisture (10 and 18% VWC), and iii) 2 rainfall periods (0 and 3 dafter herbicides application). A rainfall simulator was adjusted to simulate an 80 mm h-1 rainfall event for one and a half hour (120 mm) over plots of 1 m2. A commercial product containing diuron and hexazinone was used at rate of 3 kg ha-1 dissolved in 700 L ha-1, according to label recommendations. The amounts of water and sediments were registered and herbicides concentrations analyzed by UPLC. Herbicides attached to the sediments were estimated according to sorption data from the literature. The results were evaluated by ANOVA and means compared by Tukey test (p<0.05). Sugarcane straw decreased water, sediments, and diuron losses by runoff, but did not affect hexazinone losses. In other words, crop residues cannot prevent losses of highly soluble molecules, such as hexazinone. Greater herbicides losses were observed in the aqueous phase, even for the control treatment (without straw), since straw reduces the amounts of detached sediments. However, no difference was observed between the two levels of straw (50 and 100%), meaning that 7 t ha-1 is sufficient for mitigating water, sediments, and diuron losses by runoff. Higher soil moisture (18 versus 10%) resulted in higher herbicides runoff. Yet, rainfall period did not affect herbicide losses, indicating that 3 days were not long enough for enhancing these herbicides dissipation or sorption.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-05-05T18:33:54Z No. of bitstreams: 1 2010 - Frederico Santos Machado.pdf: 2164167 bytes, checksum: 28047d32a367720ee18ef9cf4c58be45 (MD5) / Made available in DSpace on 2017-05-05T18:33:54Z (GMT). No. of bitstreams: 1 2010 - Frederico Santos Machado.pdf: 2164167 bytes, checksum: 28047d32a367720ee18ef9cf4c58be45 (MD5) Previous issue date: 2010-05-27 / The hydric erosion is one of main environmental impact in Central Amazonia region, causing serious economic consequences for implantation and recovery of operational locations of PETROBRAS S/A oil and natural gas exploration and production sites. This study was carried through in Petroliferous Province of Urucu, municipality of Coari (AM). The objective was to quantify soil loss (SL) and runoff (SD) in different soil classes and under vegetal coverings using a portable rain simulator. Sixteen batteries of tests were done, eight batteries for each soil class (Fluventic Dystrustepts e Kanhaplic Haplustults). For each battery three repetitions had been made in the following covers: forest, forest without litter and grass. The results of Tukey test at 0.05 level showed that soil classes were not significantly different between themselves. On the other hand, the organic carbon percentage and the soil bulk density had greatest importance for the soil loss. These attributes, plus fine sand and clay, influenced most in the runoff. It was also possible to observe that runoff was the attribute of highest correlation with soil loss. The conversion of forest areas into grass increased, at least, four times the water runoff, changing it from 14.2 mm to 57.7 mm in the grass area, and, at least, two times loss of soil mass, achieving the value of 35.68 t.ha-1.year-1 in the grass area. Although with these values, grassy areas only differed significantly from the forest areas in the runoff. The runoff values tend to increase twofold when litter is removed from the forest soils, while the soil losses increased 40%. The attributes that were important for the soil classes were the same for cover types, however with differences in the attribute clay content for soil loss, and coarse sand for runoff. For the studied treatments, the attribute that showed highest correlation with soil loss was runoff. / A eros?o h?drica ? um dos principais impactos ambientais na regi?o da Amaz?nia Central, causando s?rias conseq??ncias, inclusive econ?micas, para a implanta??o e recupera??o de loca??es operacionais de explora??o e produ??o de petr?leo e g?s natural da PETROBRAS S/A. Este estudo foi realizado na Prov?ncia Petrol?fera de Urucu, munic?pio de Coari (AM) e teve como objetivo quantificar a perda de solo (PS) e o escoamento superficial (ES) em diferentes grupos de solo e coberturas vegetais, utilizando um simulador de chuva port?til. Foram efetuadas 16 baterias de testes, sendo 4 baterias para cada grupo de solo (ARGISSOLO AMARELO Al?tico, ARGISSOLO VERMELHO-AMARELO Al?tico, CAMBISSOLO H?PLICO Al?tico e CAMBISSOLO H?PLICO Tb Distr?fico). Em cada bateria foram realizados tr?s repeti??es nas seguintes coberturas: floresta, floresta sem serrapilheira e gram?nea. As classes de solo n?o diferiram significativamente entre si ao n?vel de 5%, segundo o teste de Tukey. Para a PS, a porcentagem de carbono org?nico e a densidade do solo t?m grande import?ncia para os grupos de solo. Esses atributos, mais a areia fina e argila influenciaram o ES. Tamb?m foi poss?vel observar que o escoamento foi o atributo com maior coeficiente de correla??o com a perda de solo. A convers?o das ?reas de floresta em gram?nea aumentou em no m?nimo quatro vezes a l?mina de ?gua escoada, passando de 14,2 mm para 57,7 mm na gram?nea e, no m?nimo, duas vezes a massa de solo perdida, chegando a 35,8 t.ha-1.ano-1 na gram?nea. Apesar desses valores, as ?reas cobertas por gram?neas apenas diferiram significativamente das ?reas de florestas em rela??o ao ES. Quando se retira a serrapilheira em solos florestais, os valores de escoamento dobram, enquanto que as perdas aumentam em 40%. Os atributos que tiveram import?ncia para as classes de solo foram os mesmos para os tipos de coberturas, por?m com diferen?as no atributo teor de argila para a perda de solo e no teor de areia grossa para o escoamento. Para os tratamentos estudados, o escoamento continua sendo o atributo com maior coeficiente de correla??o com a perda.

Made available in DSpace on 2015-03-26T12:31:10Z (GMT). No. of bitstreams: 1 texto completo.pdf: 3461017 bytes, checksum: c343053cbc2e3541876491e2e17050a4 (MD5) Previous issue date: 2009-08-10 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Rainfall is considered the main climatic factor related to the degradation of agricultural lands, and among their characteristics the intensity stands out as the main conditioning factor of the erosive process. The present work had the objective of evaluating the influence of different precipitation profiles in the soil and water losses. Four precipitation profiles were considered: exponential negative, forwarded double exponential, delayed double exponential and a profile with constant intensity, being the total applied depth of 55 mm and duration of 30 min. The simulator was installed in an experimental area with Inceptsol. The treatments consisted in the simulation of the four precipitation profiles in conditions of bare soil, applied three times in 24 h-intervals, characterizing three initial conditions of soil moisture: low, medium and high. Thus the treatments were defined based on the combination of the precipitation profiles and the conditions of initial soil moisture, using six replications. It was used a completely randomized design, and the water and soil losses data were submitted to the analysis of variance (ANOVA) and the Tukey's test (5%). During the first application, which consisted in the simulation of rains in soils with low initial moisture there was not superficial runoff, consequently there was not soil loss. In the second application, where the soils were with intermediate initial moisture, differences among the treatments were not obtained due to the high variability observed. In the third application, statistically significant differences among the treatments were found for soils with conditions of high moisture. The largest losses of water and soil were obtained with the negative exponential profile, followed by the delayed, forwarded and constant profiles. Therefore, it was possible to conclude that there was influence of the precipitation profiles on the soil and water losses, however only for the treatments with soils of high moisture. / A precipitação é considerada o principal fator climático relacionado à degradação de terras agrícolas e, entre suas características, a intensidade se destaca como o principal fator condicionador do processo erosivo. O presente trabalho teve por objetivo avaliar a influência de diferentes perfis de precipitação nas perdas de solo e água. Foram definidos quatro perfis de precipitação: exponencial negativo, duplo exponencial adiantado, duplo exponencial atrasado e um perfil com intensidade constante, que foram aplicados por meio de um simulador de chuvas, sendo uma lâmina total de 55 mm e duração de 30 min comum a todos os perfis. O simulador foi instalado em uma área experimental cujo solo foi classificado como Cambissolo Háplico. Os tratamentos consistiram na simulação dos quatro perfis de precipitação em condições de solo descoberto, aplicados por três vezes em intervalos de 24 h, caracterizando três condições iniciais de umidade do solo: baixa, intermediária e alta. Assim, os tratamentos foram definidos pela combinação dos perfis de precipitação e das condições de umidade inicial do solo, sendo realizadas para cada um deles seis repetições. O delineamento experimental utilizado foi o inteiramente casualizado (DIC) e os totais de perdas de água e solo submetidos à análise de variância (ANOVA) e ao teste de Tukey (5%). Durante a primeira aplicação, que consistiu na simulação de chuvas em solos com baixa umidade inicial, não houve escoamento superficial e, consequentemente, não ocorreram perdas de solo. Na segunda aplicação, condição em que os solos se encontravam com umidade inicial intermediária, não foram obtidas diferenças estatisticamente significativas entre os tratamentos devido à alta variabilidade observada. Na terceira aplicação foram encontradas diferenças estatisticamente significativas entre os tratamentos, para solos com condições de umidade próxima à saturação. As maiores perdas de água e de solo foram obtidas para o perfil exponencial negativo, seguido pelos perfis duplo exponencial atrasado, adiantado e o constante. Assim, foi possível concluir que houve influência dos perfis de precipitação nas perdas de solo e água, porém apenas para os tratamentos com umidade do solo próxima a saturação.

A canavicultura é de extrema importância para o Brasil e para o mundo. O aumento da produção de cana-de-açúcar reflete em maior uso de herbicidas, como o diuron e a hexazinona. A adoção do sistema de cana crua, em que a palha permanece sobre o solo após colheita mecanizada, implica em alteração na dinâmica ambiental destes herbicidas. Portanto, o objetivo deste trabalho foi avaliar as perdas de diuron e hexazinona por escoamento superficial em sistemas de cana crua. O experimento constou de sistema fatorial 3x2x2 (12 tratamentos) com delineamento em blocos casualizados e 4 repetições, totalizando 48 parcelas. Os fatores foram: 3 níveis de palha (0, 50% e 100% da dose = 14 t ha-1); 2 níveis de umidade de solo (10 e 18% v/v) e 2 momentos de chuva (0 e 3 dias após aplicação dos produtos). Sobre as parcelas de 1 m2, foi utilizado um simulador de chuvas ajustado para evento com intensidade de 80 mm h-1 durante uma hora e meia, resultando num volume total precipitado de 120 mm. Um produto comercial contendo diuron e hexazinona foi aplicado na dose de 3 kg ha-1 e calda de 700 L ha-1, conforme recomendações do fabricante. As quantidades de água e sedimentos escoadas foram registradas e as concentrações dos herbicidas analisadas em solução por UPLC. Os resultados foram submetidos à ANOVA e, em caso de interação, as médias foram comparadas pelo teste de Tukey (p<0,05). A quantidade de diuron e hexazinona nos sedimentos foi estimada fazendo uso dos dados de sorção da literatura. A presença de palha sobre o solo reduziu as perdas de água, sedimentos e diuron, mas não teve efeitos sobre as perdas de hexazinona. Em outras palavras, a cobertura morta não reduz as perdas de moléculas muito solúveis, como a hexazinona. As maiores perdas de diuron e hexazinona foram observadas em solução, mesmo no tratamento controle (sem palha), uma vez que a palha reduz a massa de sedimentos desprendida. No entanto, não houve diferença nas perdas entre os dois níveis de palha (50 e 100%), sugerindo que 7 t ha-1 são suficientes para atenuar as perdas de água, sedimentos e diuron. Maiores teores de água no solo (18 versus 10% v/v) implicaram em maiores perdas dos herbicidas por escoamento superficial. Já o momento da chuva não afetou as perdas dos herbicidas, indicando que 3 dias não foram suficientes para a dissipação ou maior sorção dessas moléculas. / Sugarcane is a major crop in Brazil and of great importance to the world. Higher yields implicate in higher use of pesticides, such as diuron and hexazinone. The adoption of green cane system, in which the straw is kept in the soil surface after mechanical harvesting, has changed the environmental behavior of theses herbicides. Therefore, the goal of this research was to evaluate runoff losses of diuron and hexazinone in green cane systems. The 3x2x2 (12 treatments) factorial experiment was performed in a randomized block with 4 replicates. The factors were i) 3 levels of sugarcane straw (0, 50% and 100%, based on a dose of 14 t ha-1); ii) 2 levels of initial soil moisture (10 and 18% VWC), and iii) 2 rainfall periods (0 and 3 dafter herbicides application). A rainfall simulator was adjusted to simulate an 80 mm h-1 rainfall event for one and a half hour (120 mm) over plots of 1 m2. A commercial product containing diuron and hexazinone was used at rate of 3 kg ha-1 dissolved in 700 L ha-1, according to label recommendations. The amounts of water and sediments were registered and herbicides concentrations analyzed by UPLC. Herbicides attached to the sediments were estimated according to sorption data from the literature. The results were evaluated by ANOVA and means compared by Tukey test (p<0.05). Sugarcane straw decreased water, sediments, and diuron losses by runoff, but did not affect hexazinone losses. In other words, crop residues cannot prevent losses of highly soluble molecules, such as hexazinone. Greater herbicides losses were observed in the aqueous phase, even for the control treatment (without straw), since straw reduces the amounts of detached sediments. However, no difference was observed between the two levels of straw (50 and 100%), meaning that 7 t ha-1 is sufficient for mitigating water, sediments, and diuron losses by runoff. Higher soil moisture (18 versus 10%) resulted in higher herbicides runoff. Yet, rainfall period did not affect herbicide losses, indicating that 3 days were not long enough for enhancing these herbicides dissipation or sorption.

This study measured sediment, nutrient and pesticide edge-of-field and deep percolation losses from conventional tillage (CT), strip tillage (ST), and no-till (NT) treatments in a burley tobacco production system. The field experiment results show that the CT treatment yielded more total runoff, 93.6 mm, than ST and NT. Compared to the CT treatment, ST reduced the total mass loss of NO₃⁻ by 37 percent, NH₃ by 54 percent, PO₄³⁻ by 12 percent, TP by 65 percent and TSS by 64 percent. The NT treatment reduced the total mass of NO₃⁻ by 49 percent, NH₃ by 46 percent, PO₄³⁻ by 17 percent, TP by 73 percent and TSS by 77 percent. Field experiment results showed that, respectively, the ST and NT treatments yielded 77 and 82 percent less chlorpyrifos, an insecticide, mass loss in runoff compared to CT. With respect to flumetralin loss, a growth inhibitor, the NT treatment yielded 30 percent less and ST yielded 6.8 percent more flumetralin mass, compared to CT. The percolated water results show that compared to the CT treatment, ST resulted in 33 percent less NH₃, 7.5 percent less TKN, and 39 percent less PO₄³⁻ total mass. The NT treatment yielded 41 percent less NH₃ and 20 percent less TKN total mass loss compared to the CT treatment. The NT treatment had the most NO₃⁻, PO₄³⁻, and TP mass loss below the root zone, however NT also had the most percolated water by 53 mm (838 L). The ST treatment yielded 77 percent less, and NT yielded 82 percent less chlorpyrifos mass loss compared to the CT treatment. Compared to CT, the NT treatment resulted in 30 percent less and ST yielded 7 percent more flumetralin mass in percolated water. The GLEAMS model was used to simulate runoff, nutrient, sediment and pesticide losses from the same three tillage practices evaluated in the field experiment. The model results showed that for runoff volume, TSS, nitrogen, chlorpyrifos and flumetralin in runoff, the conventional tillage practice generated greater losses than the conservation tillage practices. Compared to the field experiment results, GLEAMS under predicted nitrogen and phosphorus in percolated water. The conservation tillage practices simulated in GLEAMS were effective in minimizing the loss of agricultural pollutants. / Master of Science

The increase of animal agriculture coupled with excess manure production, and the reduced availability of land has led to the over application of animal manure on agricultural fields. The excessive application of manure is responsible for nutrient and bacterial pollution of downstream waterbodies. Manure application based on the crop phosphorus (P) requirements has been recommended as a viable method to reduce nutrient pollution. A plot scale study was conducted to measure the loss of nutrients and bacterial transport in runoff from cropland treated with poultry litter, dairy manure and inorganic fertilizer according to the P requirements of the crop. Three simulated rainfall events were conducted 1, 2 and 35 days after planting of corn. Highest P and N concentrations were observed in the runoff from plots treated with poultry litter, followed by dairy manure and inorganic fertilizer. The poultry litter treated plots exhibited highest concentrations of bioavailable P in the runoff, compared to all other treatments. The P from poultry litter treated plots was also mostly in the soluble form, which underscores the need to control the runoff from cropland in order to decrease the P losses from the poultry litter treated fields. The edge of the field nutrient concentrations observed in this study were high enough to cause severe to moderate eutrophication problems in downstream waterbodies unless they are diluted. In general, nutrient concentrations were lower during the second simulated event, compared with those from the first event. A significant reduction in the nutrient concentrations of runoff was observed from the second to the third simulated event for all the treatments. This reduction was attributed to the loss of nutrients by natural rainfall-runoff events during the time period between the second and the third simulated rainfall event, plant uptake of nutrients, sorption and leaching processes. The indicator bacteria analyzed in the present study were fecal Coliform (FC), Escherichia Coli (E.Coli) and Enterococcus (ENT). The bacterial concentrations reported in the runoff for the first and second simulated events were 104 to 105 times higher than the federal and state limits for primary contact recreation waters. No significant effect of treatments was observed on the bacterial concentrations in runoff. The highest concentrations were observed for FC, followed by ENT and EC in the runoff. The ratio of bacteria removed in runoff to the bacteria applied also followed the above trend. The concentrations of bacteria generally increased from the first to second simulated event; unlike the nutrients. However, the bacterial concentrations dropped significantly from second to the third simulated rainfall event to the levels lower than those designated for primary contact recreation water limits. This reduction was attributed to the washing away of bacteria by the heavy rainfall-runoff events in the period between second and third simulated rainfall events and the die-off of bacteria. The results reported from this study suggest that the manure application based on crop P requirements can also be a significant source of nutrient pollution and should be coupled with other best management practices (BMPs) also to reduce nutrient pollution. The results also suggest that the manure treated cropland can be a source for significant indicator bacterial pollution and appropriate BMPs are required to mitigate their effect. / Master of Science

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-04-25T20:29:14Z No. of bitstreams: 1 2012 - Eliete Nazar? Eduardo.pdf: 947644 bytes, checksum: d85c318ce9c161ce157d42e89ed6c4af (MD5) / Made available in DSpace on 2017-04-25T20:29:14Z (GMT). No. of bitstreams: 1 2012 - Eliete Nazar? Eduardo.pdf: 947644 bytes, checksum: d85c318ce9c161ce157d42e89ed6c4af (MD5) Previous issue date: 2012-02-27 / FAPERJ / The purpose of this study was to determine the soil erodibility (K) and soil cover and management factor (C) under natural and simulated rainfall in an Udult soil in Serop?dica, Rio de Janeiro State, Brazil. In the study with natural rainfall, the soil losses (SL) were evaluated from measurements in Wischmeier standard-plots in the period of 2006 to 2011, with their respective erosivity index (EI30). The soil erodibility values were calculated from the ratio of soil loss and the annual rainfall erosivity (Ka) and total period (Kt), considering the angular coefficient generated from the linear regression analysis between those parameters (Kci and Kct). For the determination of C factor under natural rainfall, it was evaluated the treatments maize in contour lines (MN) and maize in slope lines (MMA) during three years of cultivation. In the study with simulated rainfall, soil losses were evaluated during the period of September to December 2011, under the same treatments (MN and MMA). The soils erodibility under natural rainfall for 5 years of study is 0.0090 Mg ha h ha-1 MJ-1 mm-1. For the simulated rain, this value is 0.00021 Mg ha h ha-1 MJ-1 mm-1; under natural rainfall, the average values of C factor calculated are 0.0070 and 0.0132 Mg ha Mg-1 ha-1, respectively, for maize grown in contour and slope line, and 0.0932 and 0.1298 Mg ha Mg-1 ha-1 under simulated rainfall. In both studies, the C factor showed higher values in the beginning of the study period, decreasing with the evolution of culture. The higher C factor values obtained in the study with simulated rainfall are associated with higher erosivity index resulting from the characteristics adopted in the use of simulator rainfall. / O objetivo desse trabalho foi determinar a erodibilidade do solo (K) e o fator manejo e cobertura do solo (C), sob chuva natural e simulada, em um ARGISSOLO VERMELHO-AMARELO em Serop?dica (RJ), informa??es necess?rias para o planejamento do uso da terra e conserva??o do solo e da ?gua. No estudo com chuva natural foram avaliadas as perdas de solo (PS) ocorridas em parcelas padr?o de Wischmeier, no per?odo de 2006 a 2011, com seus respectivos ?ndices de erosividades (EI30). As erodibilidades do solo foram calculadas pelo quociente entre a perda de solo e a erosividade das chuvas anuais (Ka) e total no per?odo (Kt), considerando o coeficiente angular gerado na an?lise de regress?o linear entre esses mesmos par?metros (Kci e Kct). Para a determina??o do fator C, sob chuva natural foram avaliados os tratamentos de milho em n?vel (MN) e de milho morro a baixo (MMA) em tr?s anos de cultivo. No estudo com chuva simulada, as perdas de solo foram avaliadas no per?odo de setembro a dezembro de 2011, sob os mesmos tratamentos (MN e MMA). A erodibilidade do solo estudado sob chuva natural, para 5 anos de estudo ? de 0,0090 Mg ha h ha-1 MJ-1 mm-1. Para a chuva simulada, esse valor ? de 0,00021 Mg ha h ha-1 MJ-1 mm-1; sob chuva natural, os valores m?dios do fator C calculados s?o de 0,0070 e 0,0132 Mg ha Mg-1 ha-1, respectivamente, para a cultura do milho cultivado em n?vel e morro abaixo, e de 0,0932 e 0,1298 Mg ha Mg-1 ha-1 sob chuva simulada. Em ambos os estudos, o fator C apresentou maiores valores no in?cio do per?odo avaliado, decrescendo com a evolu??o da cultura. Os elevados valores do fator C obtidos no estudo com chuva simulada est?o associados ao elevado ?ndice de erosividade resultante das caracter?sticas adotadas no uso do simulador de chuva.

The overall purpose of this study was to define the water balance of feedlot pens in a Saskatchewan cattle feeding operation for a one year period. Although the initial intention of the study was focused upon an active feedlot, cattle were removed from the pens in July 2003. Therefore, the year of analysis was conducted on the manured surface of an inactive feedlot. The water balance was also performed on a scraped soil surface, since manure is removed from the pens and spread on agricultural land, leaving the pen surfaces bare for a short period of time each year. <p>During the monitoring period (Sept. 2003 to Aug. 2004), 313 mm of precipitation was received at the feedlot, but only 84 mm of that total was received before June 2004. Winter precipitation was very low (33 mm) and there was no observed runoff from it. Runoff collection weirs in operation for only part of the summer recorded no runoff. The Green-Ampt and USDA SCS runoff models, as well as a snowmelt runoff equation, were used to predict runoff from both the manure pack, as well as the scraped soil surface. Using manure and soil hydraulic parameters determined in the laboratory (from falling head permeameter measurements) and the field (from rainfall simulations), as well as incorporating the greatest 24 hour rainfall amounts and 30 minute intensities experienced at the feedlot, the USDA model found that 29 mm of runoff would occur from the scraped soil surface. Additionally, snowmelt runoff was estimated to be 19 mm for the winter precipitation received. Drainage beneath the 0.6 m soil depth was negligible and the top 0.6 m of soil experienced an increase in moisture of 54 mm. Finally, 211 mm was lost as evaporation. For the manure pack, no runoff was predicted using the Green-Ampt and USDA SCS models and snowmelt runoff equation, which corresponded well to the lack of runoff measured both from the weir and rainfall simulations. Drainage beneath 0.6 m soil depth was negligible. Of the 313 mm of precipitation that fell during the study year, 42 mm was stored within the manure pack and the rest was lost as evaporation (271 mm).

The overall purpose of this study was to define the water balance of feedlot pens in a Saskatchewan cattle feeding operation for a one year period. Although the initial intention of the study was focused upon an active feedlot, cattle were removed from the pens in July 2003. Therefore, the year of analysis was conducted on the manured surface of an inactive feedlot. The water balance was also performed on a scraped soil surface, since manure is removed from the pens and spread on agricultural land, leaving the pen surfaces bare for a short period of time each year. <p>During the monitoring period (Sept. 2003 to Aug. 2004), 313 mm of precipitation was received at the feedlot, but only 84 mm of that total was received before June 2004. Winter precipitation was very low (33 mm) and there was no observed runoff from it. Runoff collection weirs in operation for only part of the summer recorded no runoff. The Green-Ampt and USDA SCS runoff models, as well as a snowmelt runoff equation, were used to predict runoff from both the manure pack, as well as the scraped soil surface. Using manure and soil hydraulic parameters determined in the laboratory (from falling head permeameter measurements) and the field (from rainfall simulations), as well as incorporating the greatest 24 hour rainfall amounts and 30 minute intensities experienced at the feedlot, the USDA model found that 29 mm of runoff would occur from the scraped soil surface. Additionally, snowmelt runoff was estimated to be 19 mm for the winter precipitation received. Drainage beneath the 0.6 m soil depth was negligible and the top 0.6 m of soil experienced an increase in moisture of 54 mm. Finally, 211 mm was lost as evaporation. For the manure pack, no runoff was predicted using the Green-Ampt and USDA SCS models and snowmelt runoff equation, which corresponded well to the lack of runoff measured both from the weir and rainfall simulations. Drainage beneath 0.6 m soil depth was negligible. Of the 313 mm of precipitation that fell during the study year, 42 mm was stored within the manure pack and the rest was lost as evaporation (271 mm).