Submitted by Alyson Bueno Francisco null (33432427808) on 2017-08-11T12:14:51Z No. of bitstreams: 1 Tese de doutorado A B Francisco.pdf: 10647120 bytes, checksum: b285cedbc09019fbb08981d29c331f11 (MD5) / Rejected by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br), reason: Solicitado pelo autor. on 2017-08-16T17:08:43Z (GMT) / Submitted by Alyson Bueno Francisco null (33432427808) on 2017-08-16T17:31:14Z No. of bitstreams: 1 Tese A B Francisco.pdf: 10686416 bytes, checksum: c31c9ad77d0f43445d40956e5016092b (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-08-23T14:29:47Z (GMT) No. of bitstreams: 1 francisco_ab_dr_prud.pdf: 10686416 bytes, checksum: c31c9ad77d0f43445d40956e5016092b (MD5) / Made available in DSpace on 2017-08-23T14:29:47Z (GMT). No. of bitstreams: 1 francisco_ab_dr_prud.pdf: 10686416 bytes, checksum: c31c9ad77d0f43445d40956e5016092b (MD5) Previous issue date: 2017-07-31 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Esta tese apresenta como objetivo realizar uma análise espacial e temporal da boçoroca do Córrego do Grito, localizada na área do perímetro urbano da cidade de Rancharia-SP e apresentar as propostas de controle desta erosão periurbana. Esta boçoroca apresenta indícios de desenvolvimento que remontam a década de 1960, episódios recentes de danos gerados à infraestrutura urbana e presença de processos erosivos ativos nas margens. Para apresentar uma análise geográfica deste caso de processo erosivo são apresentados aspectos do histórico de uso da terra no município de Rancharia e aspectos físico-geográficos e as mudanças de uso da terra na microbacia do Córrego do Grito e em escala de detalhe as informações cartográficas sobre a boçoroca. Diante deste caso de processo erosivo que se perpetua por cinco décadas, nesta tese são apresentadas informações geográficas detalhadas da boçoroca a partir de dados coletados em levantamentos topográficos com equipamentos geodésicos. Durante vinte e quatro meses foi realizado um monitoramento topográfico de parcelas da boçoroca, onde foi constatada uma erosão de rebordo superior a 1,5 m em quatro pontos e uma média de 0,85 m, em toda a parcela monitorada ocorreu uma perda de 305,9 metros quadrados de área. Em relação às propostas de controle do processo erosivo, foram implantados barramentos com fibra vegetal (Bambusa bambos L.) numa parcela experimental com o monitoramento do nível de solo por meio de pinos de erosão, e a partir de uma análise comparativa sendo constatada uma média de movimentação de solo superior na parcela experimental sem o uso de barramentos. A partir das mensurações dos níveis de movimentação do solo e de dados de densidade do solo foram apresentadas estimativas de perda de solo nas parcelas experimentais. Na área da parcela experimental com barramentos foram plantadas espécies vegetais nativas com o intuito de contribuir na recuperação da área degradada. Neste sentido, a partir de informações geográficas detalhadas sobre a área degradada pela boçoroca do Córrego do Grito, a tese visa contribuir no planejamento de futuras medidas para uma recuperação efetiva desta área em Rancharia. A partir da proposta empírica apresentada nesta tese, são apresentadas formas de se repensar sobre a filosofia de Francis Bacon e suas contribuições na Geografia. / This thesis aims to perform a spatial and temporal analysis of the gully of Grito Stream, located in the urban perimeter of the city of Rancharia, and present the proposals to control this peri-urban erosion. This gully presents evidence of development dating back to the 1960s, recent episodes of damage to urban infrastructure and the presence of active erosive processes at the banks. To present a geographic analysis of this case of erosion process are presented aspects of land use history in the municipality of Rancharia and physical-geographic aspects and land use changes in the watershed of the Grito Stream and in detail scale the cartographical information on the gully. In view of this case of erosive process that is perpetuated for five decades, in this thesis detailed geographic information of the gully is presented from data collected in topographic surveys with geodesic equipment. For twenty-four months, a topographic monitoring of borehole plots was carried out, where a ridge erosion greater than 1.5 m was observed in four points and an average of 0.85 m, in all the monitored plot there was a loss of 305.9 square meters of area. In relation to the erosion process control proposals, buses with plant fiber (Bambusa bambos L.) were implanted in an experimental plot with soil level monitoring by means of erosion pins, and from a comparative analysis there is a greater upper soil movement in the experimental plot without the use of buses. Based on the measurements of soil movement levels and soil density data, estimates of soil loss were presented in the experimental plots. In the area of the experimental plot with barriers native plant species were planted with the intention of contributing to the recovery of the degraded area. In this sense, based on detailed geographic information on the area degraded by the gully of the Grito Stream, the thesis aims to contribute in the planning of future measures for an effective recovery of this area in Rancharia. From the empirical proposal presented in this thesis are presented ways to rethink the philosophy of Bacon and his contributions on Geography. / FAPESP: 2013/05664-4

Orientador: Morel de Passos e Carvalho / Resumo: Um índice de erosividade da chuva que se destaque e auxilie na estimativa da erosão do solo é altamente desejável. O parâmetro EI30 é o mais utilizado no mundo, no entanto, inúmeros trabalhos nacionais têm comprovado a eficácia de modelos que envolvem a enxurrada. O trabalho foi desenvolvido entre dezembro/2012 a agosto/2014, em um Argissolo Vermelho, da unidade experimental de Aquidauana (MS), pertencente à Universidade Estadual de Mato Grosso do Sul (UEMS). Foram selecionadas 92 chuvas individuais erosivas para o cálculo dos modelos de erosividade, e coletados os dados de perdas de solo e de enxurrada provenientes da parcela padrão. Parâmetros de erosividade da chuva, da enxurrada e da chuva-enxurrada foram analisados por meio de regressão linear simples, múltipla e não-linear, com a finalidade de: (a) definir o fator erosividade para chuvas individuais na tentativa de avaliar a eficiência entre si de parâmetros da chuva, da enxurrada e da chuva-enxurrada, visando aprimorar o uso da EUPS, EUPSM e da EUPSR local, e (b) determinar o fator erodibilidade para o solo pesquisado. Portanto, concluiu-se que: 1) No âmbito da EUPS, o índice EI30 de Wischmeier e Smith foi convenientemente adequado para predizer as perdas de solo das chuvas individuais erosivas locais. Assim, a erosão de Aquidauana pode ser calculada pela expressão: A*=3,7323+3,1171.10-2.EI30, e o fator erosividade da chuva em questão deve ser calculado pelo emprego do índice de erosividade da chuva EI30; 2) Já no âmbi... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: An index of erosivity rainfall that can stand out and assist in the estimation of soil erosion is highly desirable. The EI30 parameter is the most widely used in the world; however, many national papers have proved the effectiveness of models that involve the runoff. This study was carried out between December 2012 to August/2014, in the Experimental Unit of Aquidauana (MS), State University of Mato Grosso do Sul (UEMS), in a Dystrofic Tropustult. A set of 92 individual erosive rainfalls were selected for the calculation of the erosivity models and collected the data of soil losses and runoff from the unit plot. Erosivity parameters from rainfall, runoff and rainfall-runoff were analyzed through simple linear regression, multiple and non-linear, with the purpose of: (a) define the erosivity factor for individual rainfalls in an attempt to evaluate the efficiency between the parameters from rainfall, runoff and rainfall-runoff, aiming to improve the use of the USLE, MUSLE and RUSLE local, and (b) determine the factor erodibility for the soil of unit plot. Therefore, it was concluded that: 1) In the context of USLE, the Wischmeier and Smith EI30 was conveniently suited for predicting soil losses of individual erosive rainfalls local. Thus, Aquidauana erosion can be calculated using the expression: A*=3.7323+3.1171.10-2 .EI30, and erosivity rainfall factor shall be calculated using erosivity index rainfall EI30; 2) By the other hand, in the context of MUSLE and RUSLE, the local ... (Complete abstract click electronic access below) / Doutor

Thesis (DTech (Environmental-health))--Cape Peninsula University of Technology, 2018. / The management of agricultural soil and its sustainable use, namely productivity, is paramount to the agricultural industry worldwide. Large-scale agricultural product producers and scientists emphasise using environmentally benign methods to increase agricultural production such as taking a green chemistry approach to agricultural activities and/or using cultivation techniques for the bio-augmentation of agricultural soil. Some of these agricultural products, such as cassava (Manihot esculenta), produce cyanogens which promote the infestation of a cyanogen-resistant microbial species known to produce mycotoxins during decomposition. Although cyanogens and mycotoxins are important components in the functioning of the earth system and agricultural soil, their cumulative effects can result in reduced soil productivity, hence degradation. Furthermore, the presence of mycotoxins in the environment and agricultural produce is hazardous to the environment, including the biotic communities in soil and humans. Therefore, an environmentally benign (green chemistry approach) method for the reduction of cyanogens and mycotoxins was proposed for this research study. The method investigated had to be applicable in-situ for the biodegradation of cyanogens and mycotoxins. Their reduction from decomposing cassava in cultivated soil, which can be used on a small and large scale, would mitigate deleterious effects of a less reported, unknown mycotoxins producer (fungal species), Cunninghamella bertholletiae (KT275316), found to be a free cyanide- (CN-) resistant isolate. The C. bertholletiae was isolated from decomposing cassava tubers and silt, subsequent to culturing on potato dextrose agar (PDA) and in an equivalent volume of nutrient broth (NB) containing KCN (4mg/40mL) at 30 °C for 120 hrs. The isolate demonstrated an ability to biodegrade CN- into NH3 and NO3. NH3 and NO3 are nitrogenous by-products produced when young cassava plants are cultivated in a controlled environment, with 80% of the initial CN- concentration being efficiently degraded to NH3/NO3 at a conversion rate of 77.5% and 72.5% (fungus from silt and cassava), respectively, within 120 hrs. From this research, it was observed that Sub-Saharan Africa is the largest contributor to the CN- load into the environment; from cassava cultivation as per FAO data. The quantity of CN- released was estimated at 0.025x10-3 to 6.71 ppq, with further increases of 60.5% being projected to be released into the environment by 2024. As such, it was hypothetically assumed that numerous species in cassava-cultivated soil become CN- resistant as they are exposed to CN- from decomposing cassava, becoming pathogenic thus antigonistic towards other biota in cassava-cultivated soil. Consequently, the pathogenicity of the isolate was investigated against organisms (n = 12) from cassava-cultivated soil. The isolate demonstrated inhibitory pathogenic activity against some soil bacterial communities such as Oligella ureolytica, Acinetobacter sp., Pseudomonas luteola and Sphingomonas paucimobilis. The isolate also demonstrated minor antagonistic effects against Myroides sp., Stenotrophomonas maltophilia, Candida lipolytica, Cryptococcus albidus and Rhodotorula sp.. Further research to identify extracellular metabolites produced by this organism, using a fermentation method was also carried out using a liquid state fermentation technique. 30 mL Erlenmeyer flasks containing 25 mL of NB/KCN (source of CN-) at 37 °C for 168 hrs, with a volume of (5 mL), extracts from the fermentation being filtered, centrifuged, mixed with chloroform for a liquid-liquid extraction procedure subsequent to a nitrogen-facilitated blow-down technique and reconstitution with 100% analytical grade methanol, for LC/MS-TOF 6230 analysis. The analysis revealed that the isolate was able to produce the mycotoxins/secondary metabolites, Fumonisin B1 (FB1) and Deoxynivalenol (DON). Though the isolate (KT275316) demonstrated the ability to biodegrade cyanide as well as produce mycotoxin, an environmentally benign strategy (green chemistry method) with a potential to biodegrade CN-/NH3/NO3/NO2 for the biodegradation of mycotoxins was evaluated, including the identification of biodegradation by-products post-biodegradation treatment. Thus, plant extracts from Nepenthes mirabilis were found to contain enzymes such as carboxylesterase, β-glucosidase, β-glucoronidase and phosphatidyl inositol phospholipase C (identified using both quantitative and qualitative methods). The plant extracts were used with treated samples from the fermentation and were subjected to biodegradation. Thus, resulting in biodegradation by-products such as Heptadecanone Octadecanamide, Octadecenal for FB1 and Tolmetin for DON, respectively. For future research, it is therefore recommended that plant extracts with similar properties to those observed for N. mirabilis extracts (juice) be sought for application of the proposed method.

Orientador: Paulo Sergio Graziano Magalhães / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-09T21:21:28Z (GMT). No. of bitstreams: 1 Buscarato_EderAlexandre_M.pdf: 14445069 bytes, checksum: c3e2d83e7b2d506697ea88ad7cc248cf (MD5) Previous issue date: 2007 / Resumo: Nas áreas de reflorestamento de pinus e eucaliptos onde não é utilizada a eliminação da cepa através da queima e do preparo intensivo do solo, o plantio das novas mudas passou a ser feito na entrelinha de cepas. Acreditava-se que após 7 anos, quando a floresta alcança o seu ponto de corte, as cepas do plantio anterior teriam sido decompostas pela ação de microorganismos. Contudo observou-se que as cepas de plantios anteriores permanecem no campo e atualmente o problema com excesso de cepas em área de plantio florestal, acarreta atrasos nas operações, quebra e redução de vida útil de equipamentos, aumento do custo na produção de florestas. Esse processo de decomposição é muito variado, depende de uma serie de fatores como material genético, umidade, temperatura, etc. Os meios mecânicos de eliminação de cepas em larga escala disponíveis no mercado, são caros e lentos, além de provocar muita movimentação de material orgânico e solo. O presente trabalho teve por objetivo caracterizar a resistência mecânica das raízes de cepas de eucalipto, para obter dados para o projeto de equipamento de eliminação de cepas. A partir de cepas de 7 anos sem recondução, obtidas em campo, foi realizado levantamento da força específica necessária para o corte das raízes localizadas a 400 mm de profundidade (pivotantes) e a um raio de 500 mm do centro da cepa (laterais). Utilizou-se neste levantamento ferramentas de corte com 3 ângulos de posição e 3 ângulos de cunha distintos e cepas oriundas de árvores cultivadas em solos argilosos e arenosos. Realizou-se também avaliação da distribuição radicular em torno da cepa. Os resultados mostraram que não existe uma diferença significativa entre as raízes em função de sua localização em torno da cepa, e também em relação ao tipo de solo onde a árvore foi cultivada. Os ensaios de campo mostram também que a força específica de corte das raízes é muito pouco influenciada pelo ângulo de ataque da ferramenta ou o seu ângulo de corte, devido principalmente a disposição aleatória das raízes em relação à linha de avanço da ferramenta / Abstract: In the areas of pines and eucalyptus reforestation where the elimination of the stump is not endorse through burning or intensive soil preparation, planting of the new sprout was done in interline of stumps. It was understood that after 7 years, when the forest reaches its harvest age, the stumps of the previous plantation would have been decomposed by the action of microorganisms. However, it was observed that the stumps of previous crop remained in the field. Now the problem with excess of stumps in area of forest growing cause delay in filed operations, breakdown and reduction of equipments operational life and cost rising of forests production. The decomposition process varied, as function of a series of factors such as genetic material, humidity, temperature, etc. The mechanical methods for stumps elimination in wide scale available in the market are expensive and slow, besides provoking a lot of movement of organic material and soil. The present research project had as the main objective characterizing the mechanical resistance the eucalyptus stumps roots, to obtain data for the design of equipment for stumps elimination. From 7 year-old stumps obtained in the field, the specific forces necessary to cut roots located to 400 depth mm and the a radius of 500 mm from the center of the stump was determined. In the experimental work, cutting tools with 3 different rake angles and tools angles and stumps originating from of trees cultivated in clay and sandy soils were uded. An evaluation of the root distribution around the stump was also realized. The results showed that, does not exist a significant difference among the roots as function of its location around the stump, and in relation to the soil type where the tree was cultivated. The field-test also show that the specific force to cut of the roots is very a low influenced by the rake angle or the tool angle, due mainly to the aleatory position of the roots in relation to line of forward displacement of the tool / Mestrado / Agua e Solo / Mestre em Engenharia Agrícola

Submitted by (lucia.rodrigues@ufrpe.br) on 2016-08-18T12:55:56Z No. of bitstreams: 1 Victor Casimiro Piscoya.pdf: 3833796 bytes, checksum: 50d224f4ff552ddbddd540defbf11f6b (MD5) / Made available in DSpace on 2016-08-18T12:55:56Z (GMT). No. of bitstreams: 1 Victor Casimiro Piscoya.pdf: 3833796 bytes, checksum: 50d224f4ff552ddbddd540defbf11f6b (MD5) Previous issue date: 2012-01-09 / Sediment delivery ratio is the parameter which involves the sediment yield in watersheds and sums all sediment promptly detachment by several ways of erosion. Evaluating technologies of setting the riparian vegetation, based on yield sediment in watersheds are increasingly important to environmental preservation. Thus, the aim of this research was to set the width of riparian vegetation in Jacu semiarid stream (Pernambuco) in function of sediment delivery ratio and sediment yield. Therefore, it was calculated the rates of interrill and rill erosion by yield testing under shrub and bare Inceptisols conditions, and it was carried out direct measurement campaigns of suspended sediment and bedload, by means of US DH – 48 e US BLH – 84, respectively. The sediment yield obtained in Jacu stream was considered low. The soil loss due to interril erosion under bare conditions equal to 8.43 t ha-1 was considered high, as well as the same way for the values of rill erosion with erodibility equal to 0.0021142 kg N-1 s-1 and critical shear stress (τc) equal to 2.34 Pa. The mean value of sediment delivery ratio of Jacu watershed was equal to 0.165 and ranged from 0.29 (2008) to 0.026 (2010). This variation is associated with the natural variability of semiarid environment, indicating the necessity of assessment in a large period of years to improve the knowledge about the sediment delivery ratio of Jacu semiarid watershed. The determination of 15 m for the width of riparian vegetation from Jacu stream in function of sediment yield was considered promising for the small watershed conditions. / A taxa de entrega de sedimentos é um parâmetro de escala que envolve a produção de sedimentos da bacia hidrográfica e a soma de todo sedimento pontualmente desagregado pelas diversas formas de erosão. Avaliar as tecnologias de dimensionamento de faixa ripária, baseado na produção de sedimentos em bacias hidrográficas é cada vez mais importante para preservação ambiental. Dessa maneira, o objetivo desta pesquisa foi dimensionar a largura da faixa de vegetação ripária do riacho Jacu, semiárido de Pernambuco, em função da taxa de entrega e produção de sedimentos. Para tal, foram calculadas as taxas de erosão em entressulcos e sulcos por meio de ensaios de campo sob as condições de caatinga e Cambissolo descoberto. As campanhas de medição direta do sedimento em suspensão e de fundo foram realizadas utilizando os amostradores US DH – 48 e US BLH – 84, respectivamente. Os valores de produção de sedimentos obtidos da bacia do Jacu foram considerados baixos. As perdas de solo pela erosão em entressulcos para o Cambissolo descoberto, de 8,43 t ha-1, foram altas, bem como as de erosão em sulcos, com erodibilidade de 0,0021142 kg N-1s-1 e a tensão crítica de cisalhamento (τc) de 2,34 Pa. O valor médio da taxa de entrega de sedimentos da bacia do Jacu foi de 0,165, com variação de 0,29 no ano de 2008 a 0,026 para o ano de 2010. Essa variação está associada à variabilidade natural do ambiente semiárido, indicando a necessidade de avaliação em um período maior para um melhor conhecimento da taxa de entrega de sedimentos da bacia semiárida do riacho Jacu. A determinação da largura de 15 metros para as faixas de vegetação do riacho Jacu, em função da produção de sedimentos mostrou-se promissora para as condições de uma pequena bacia hidrográfica.

Made available in DSpace on 2014-10-09T12:35:00Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:18Z (GMT). No. of bitstreams: 0 / Elementos tóxicos podem provocar impacto na qualidade ambiental dos solos e representar risco à saúde humana. As cinzas leves de carvão são uma fonte de elementos tóxicos e são comumente dispostas de maneira inadequada sobre o solo nas proximidades das usinas termelétricas, onde esses elementos podem ser lixiviados pela chuva, transportados para as fontes de águas naturais e absorvidos pela fauna e flora do solo, podendo assim, entrar na cadeia alimentar humana. Neste estudo foi avaliada a mobilidade dos elementos As, Cd, Zn, Pb e Mo em colunas de solo franco arenoso com cinza de carvão da usina termelétrica de Figueira, Paraná. Para tanto, colunas de cinza de carvão, solo e solo coberto com cinza foram lixiviadas com uma solução ácida ao longo de 336 dias e as amostras de cinza, solo e percolado das colunas foram caracterizadas quanto à concentração dos elementos e propriedades físicas, químicas e mineralógicas. Os resultados obtidos mostraram que o Pb não foi lixiviado da cinza de carvão, indicando que a lixiviação de Pb da cinza de carvão não representa risco ambiental. O Cd foi o elemento mais retido pelo solo franco arenoso, seguido de As. O Mo foi lixiviado da cinza de carvão, mas não foi detectado no solo e nos percolados das colunas de solo+cinza. Nas condições de estudo, o Zn não representou risco ambiental. Observou-se também que a concentração de As no solo excedeu o valor de intervenção para área de proteção máxima estabelecido pela Companhia Ambiental do Estado de São Paulo (CETESB) e a concentração de Cd no solo excedeu o valor de qualidade de referência estabelecido pela mesma companhia ambiental. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

No Brasil, e especialmente no estado de São Paulo na região do Vale do Paraíba, a silvicultura com o cultivo do eucalipto está se expandindo para as áreas declivosas, ocupadas com pastagens degradadas, devido ao limitado valor agropecuário destas topografias e sua maior aptidão florestal. Tais áreas estão naturalmente mais sujeitas à erosão hídrica, a qual reduz a produtividade florestal e impacta os cursos da água. Desta forma, os métodos de preparo de solo devem ser criteriosamente definidos para possibilitar o adequado crescimento inicial das florestas concomitantemente à conservação do solo. Assim, o presente trabalho teve como objetivo avaliar o efeito de diferentes métodos de preparo de solo sobre as perdas de solo e água, por erosão, e sobre o desenvolvimento inicial de plantio clonal, de E. grandis, em áreas declivosas. O ensaio foi instalado num delineamento fatorial 3x2, com três intensidades de preparo (coveamento manual, coveamento mecânico e subsolagem a favor do declive) e dois sistemas de manejo de resíduos de colheita (com e sem resíduos), com 4 repetições, num Argissolo Vermelho - Amarelo Distrófico (textura média/argilosa), com declividade média de 21%, no município de Igaratá-SP. A perda de solo e o crescimento da floresta foram avaliados durante 1 ano, entre março de 2004 e fevereiro de 2005. Em dois tratamentos, o com coveamento manual e manutenção dos resíduos (MAC) e na subsolagem sem resíduos (SUS), a erosão foi medida diretamente através do método da parcela padrão, instaladas em todas as repetições, e com dimensões de 14x24 metros. Uma parcela padrão adicional, sem preparo e sem resíduos, foi também instalada. As erosões mensuradas foram agrupadas e analisadas em três períodos (0 a 2, 3 a 7, e 8 a 12 meses). Para os demais tratamentos, a erosão foi estimada por modelos (chamados de por período e global) gerados por regressões lineares múltiplas entre a erosão observada nas parcelas padrão dos tratamentos MAC e SUS, e variáveis independentes oriundas dos atributos locais de cada parcela e das medições de 15 pinos nelas instalados. O solo e a água erodidos e coletados nas parcelas padrão foram analisados quimicamente para quantificar os macronutrientes perdidos. O crescimento inicial do eucalipto foi determinado estimando-se a cobertura do solo e a biomassa da parte aérea aos 3, 6, 9 e 12 meses. Para as parcelas padrão, houve maior erosão no tratamento SUS do que no MAC (P=0.07), com valores médios de 12,9 e 2,4 Mg ha-1 ano-1, respectivamente, e para ambos houve significativa redução da erosão com o desenvolvimento da floresta, o que não ocorreu na parcela testemunha. Os modelos preditivos de erosão só retiveram a variável dos pinos para os 2 primeiros períodos, quando as erosões foram maiores. Para o terceiro período e para o modelo global, apenas variáveis locais foram retidas: volume de solo mobilizado, cobertura do solo e teor de argila. Ambos modelos apresentaram a mesma tendência de estimar maior erosão no tratamento com subsolagem, o qual também obteve, um pequeno ganho de crescimento ao final do primeiro ano (9%). Em termos de resíduos, sua presença reduziu levemente o crescimento (9%). A maior parte da perda de nutrientes, 60%, ocorreu no solo erodido, e suplantam a entrada de nutrientes via chuva, porém são muito inferiores à exportação pela remoção dos resíduos florestais. Assim, ponderando-se os ganhos de crescimento inicial e as perdas erosivas esperadas, identifica-se para o sítio como melhor opção a manutenção dos resíduos com o uso de coveamento mecânico. / In Brazil, and especially in the state of São Paulo in the “Vale do Paraíba” region, eucalypt plantation is expanding to high declivity areas occupied with degraded pastures due to the limited agricultural value of these topographies and its greatest forest aptitude. Such areas are naturally more susceptible to the hydric erosion, which reduces the forest productivity and causes impacts in creeks and lakes. Therefore, the methods of soil preparation should be carefully defined to improve the initial growth of the forests together with soil conservation. Thus, this study had the objective to evaluate the effect of different methods of soil preparation on the soil and water losses by erosion, and on the initial development of E.grandis, clone, in steep areas. The experiment was installed in a 3 x 2 factorial design, with three intensities of soil preparation (manual pitting, mechanical pitting and downhill subsoiling) and two systems of residues management (with and without harvesting residues), with 4 blocks, in a Red-Yellow Argisol dystrophic (medium/clayey texture), with an average declivity of 20,3%, in Igaratá-SP. The soil loss and the growth of the forest were followed during 1 year, between March of 2004 and February of 2005. In two treatments, manual pit and maintenance of the residues (MAC) and in the subsoiling without residues (SUS), the erosion was measured directly through the method of the standart plots, installed in all the repetitions, and with 14 x 24 meters dimensions. An additional standard plot without soil preparation and residues was also installed. The erosion data was grouped and analyzed in three periods (0 to 2, 3 to 7, and 8 to 12 months). For the other treatments, the erosion was estimated using models (named per period and global) from multiple linear regressions between the erosion observed in the treatments MAC and SUS, and independent variables originated from local attributes of each plot and from the measurement of 15 pins installed inside the plots. The soil and the water eroded, collected in the standard plots were chemically analyzed to quantify the lost of macronutrients. The initial growth of the eucalypt was determined estimating soil coverage and aboveground biomass at the 3, 6, 9 and 12 months. For the standard-plots, there was larger erosion in the treatment SUS than in MAC (P=0.07), with average values of 12.9 and 2.4 Mg ha-1 year-1, respectively. For both treatments, the erosion was reduced with the growth of the forest. The erosion models only retained the variable of the pins for the first 2 periods, when erosions were larger. For the third period and for the global model, just local variables were retained: volume of prepared soil, soil coverage and clay content. Both models presented the same trend of predicting larger erosion in the treatment with subsoiling, which also obtained a small growth gain at the end of the first year (9%). For the residues, its maintenance in the area reduced the growth slightly (9%), similar to the mechanical pitty. Most of the loss of nutrients, 60%, were in the eroded soil, and this amount was larger than the rainfall inputs, but much smaller than the exportation by removing the forest residues. Thus, pondering the gains of initial growth and the expected erosion losses, the maintenance of the residues in the site together with the use of mechanical pitting can be identified as the best soil preparation option for these areas.

M.Ing. (Civil Engineering) / The purpose of this study was to determine the effectiveness of a sisal fibre natural geotextile in controlling the rate and extent of soil erosion. The effectiveness of this locally produced material was compared to other natural fibre geotextiles and other methods commonly used for the control of soil erosion. The different materials and methods were tested under the same conditions to compare the relative effectiveness of these products. The various erosion control products were subjected to laboratory tests. A rainfall simulator and an adjustable slope simulator were used to simulate the process of soil erosion. During these tests the effectiveness of the different products in controlling soil erosion was measured and conclusions were made about the effectiveness of the products. Mechanical sieve analysis tests were used to determine the erodibility of the different soil particles. Field trials that made use of the sisal fibre geotextile are also discussed.

Geotextiles have been used for many years in different parts of the world to promote soil conservation and to combat erosion. Such geotextiles may be synthetic (usually some form of plastic, sometimes with wire), or natural (usually some form of fibrous material). Work carried out at the University of Wolverhampton (UK) on the effectiveness of mats made from palm tree leaves sourced from the Gambia, West Africa led to a research project funded by the EU, which ran from October 2005 to February 2009, comprising the participation of four EU countries (UK, Belgium, Hungary and Lithuania) and six developing” countries (Brazil, Gambia, South Africa, Thailand, China and Vietnam). Research carried out in South Africa used mats made from the leaves of the Lala palm (Hyperhene coriacea). These mats are easy to make, flexible, durable and completely biodegradable. They cover approximately 40% of the soil surface, allowing space for vegetation to emerge, and add 1.3 kg of dry organic matter to each m2 of soil. Furthermore, they have a water retention capacity of 1.8 l kg-1 m-2, their N, K, S and P percentages are high, they have low sodium and aluminium values and a favourable C/N ratio. Firstly, trials were done on 20 South African soils and 10 mine tailings materials using a rainfall simulator. The soils varied considerably with respect to their textural, chemical and mineralogical properties as well as annual precipitation and geological origin. Erosion parameters varied greatly within, and to a much lesser extent between, the two different materials. Several significant correlations were obtained. Sediment load (SL) had the best correlation with kaolinite content and with fine sand content, while for runoff, the best correlation was with organic carbon content. When the samples were covered with palm mats values for final infiltration rate (FI) percentage stable aggregates (SA) and inter-rill erodibility (Ki) values were similar to those of bare materials and the amount of runoff was slightly higher. SL, however, was reduced by +65%. The next stage was to carry out a range of field trials, using runoff plots. Plots at four localities (Bergville, Ladybrand, Roodeplaat and Mabula) were used. Results showed that average runoff under the palm mats decreased by between 38% and 70%, compared to bare soil. Sediment concentration under the mats decreased by between 38% and 89%, using three combinations of slope, mat density and mesh size. Splash erosion at Roodeplaat decreased by between 62% and 68%, while re-vegetation at Ladybrand and Mabula increased by between 38% and 58%, with organic carbon content and topsoil accumulation also increasing under the mats. Various trials (using both the rainfall simulator and runoff plots) were carried out to evaluate the effects of reduced mat density and increased mesh size. Results from the other participating countries (25% to 95% reduction in runoff) confirm that there is much potential to use organic, bio-degradable, easy to manufacture geotextiles such as palm leaf mats, especially to combine employment opportunities with enhanced environmental protection in many susceptible areas of South Africa. / Thesis (PhD)--University of Pretoria, 2014. / gm2014 / Plant Production and Soil Science / unrestricted

This thesis aimed at measuring the economic costs of soil degradation and to determine factors that influence the incidence and extent of adoption of soil conservation technologies by smallholder farmers in Malawi. A dynamic optimisation model was used to derive and analyse the optimal conditions for soil resource extraction and use in Malawi, while a selective tobit model was used to simulate the two-step decision-making process of farmers with respect to adoption of soil conservation technologies. Soil degradation has long-term consequences and static models, which form the bulk of studies that have so far been carried out in Africa on this topic, do not account for the inter-temporal dimension of optimal resource management. To deal with this shortcoming, this thesis used an inter-temporal optimisation framework, which considers soil in a time-dependent resource extraction perspective. This thesis has demonstrated that soil degradation is causing an enormous reduction in the productive value of smallholder land in Malawi. Current user cost of soil quality based on current practices of smallholder farmers, which represents annual loss in productive value of land, was estimated to be US$21 per hectare. Based on this value and land area under smallholder agriculture in Malawi, economic costs of soil degradation among smallholder farmers were estimated to amount to 14 per cent of the agricultural GDP. If left unabated, soil degradation threatens not only the future of smallholder agriculture but also, economic growth prospects of the nation. Although not operating on the SS optimal path in terms of soil resource management, current practices show that smallholder farmers in Malawi still consider, to certain degree, the dynamic costs in soil resource use. Hence, there is no strong evidence to suggest that current trends in land degradation are due to an institution failure (i.e., smallholder farmers have private incentives to conserve their soil resource). A result that suggests presence of other factors, most likely market distortions, behind existing deviations of farmers' practices from dynamic optimum. Government's serious support of the input and output market reforms is important not only to make the markets work but also, to make smallholder agriculture a profitable enterprise. It is only when smallholder agriculture becomes profitable that farmers can seriously invest in the soil resource. Agricultural support programs such as "food for work" if extended to include soil conservation, could lead to substantial curtailment of soil erosion since farmers can invest their labour in their own gardens during the critical times of land preparation. The sensitivity analysis indicated that increasing the discount rate to' 5%, SS solutions were close to current practice solutions. This suggests that one reason smallholder farmers are exploiting the soil resource is because they have a higher time preference. The high levels of poverty, especially among the smallholder subsistence farmers in Malawi, entail that farming households are more concerned with their survival now than their future well being. The study estimated an optimal output of 1.5tonlha and nitrogen fertiliser rate of 49 kg/ha at SS. The fertiliser estimates are based on smallholder farming system that incorporates soil conservation. In one of the most detailed studies on nitrogen use efficiency in Malawi, Itimu (1997) indicated that with the incorporation of manure, nitrogen fertiliser use dropped from 60 to 30 kg/ha to produce about 2.5 tons of maize. Malawi uses area specific recommendations for fertiliser application. However, using "best bet" technologies, at least 35kgN/ha is recommended for smallholder farmers on average. The SS optimum fertiliser estimated in the current study was somehow higher due to the fact that an inter-temporal framework, which considered the dynamic costs of soil nutrient extraction, was used. Results from fertiliser recommendation trials may be reinforced if researchers consider the inter-temporal nature and dynamic costs associated with the use of soil. The selective tobit model results indicate that factors that influence smallholder farmers' decisions to adopt soil conservation technologies may not necessarily be the same factors that influence subsequent decision on levels of adoption. The implication of this finding is that different policy prescriptions on soil conservation should strictly be guided by the goals the government wants to achieve. With fertiliser prices being out of the reach of most smallholder farmers in Malawi, soil conservation is one of the reliable options available to reduce soil degradation. However, any policy aimed at improving adoption of soil conservation technologies among smallholder farmers would succeed only if the various needs of smallholder farmers at the two decision stages are properly identified and addressed. / Thesis (PhD (Agricultural Economics))--University of Pretoria, 2006. / Agricultural Economics, Extension and Rural Development / unrestricted