Made available in DSpace on 2014-08-13T14:51:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-02-27Bitstream added on 2014-08-13T17:59:36Z : No. of bitstreams: 1 000776536.pdf: 4004778 bytes, checksum: 130c761378a2ecf404216b1a93c35cce (MD5) / Os atributos físicos e químicos do solo caminham lado a lado, e a ciência busca aprimorar o entendimento a respeito da interação dos mesmos, visando contemplar a sustentabilidade pela conservação do solo e de seus recursos naturais, utilizando o próprio sistema solo como uma ferramenta para redução das práticas antrópicas. O objetivo desse estudo foi avaliar os atributos físicos e químicos do solo submetido a diferentes cultivos de outono-inverno estabelecidos há cinco anos em sistema de semeadura direta e esclarecer qual a influência desses atributos na produtividade de grãos da soja. O experimento foi conduzido em Latossolo Vermelho distroférrico de textura argilosa. Foram estabelecidos quatro tratamentos de outono-inverno, Brachiaria ruziziensis (B), milho (M), milho consorciado com Brachiaria ruziziensis (M+B) e feijão caupi (C) e no verão foi cultivado soja. Foram realizadas coletas de solo, durante o período de florescimento da soja, para as análises física e química, foram retiradas também amostras de raízes da soja. Ao final do experimento foi realizada a colheita da soja para determinar a produtividade de grãos. Houve redução da macroporosidade e aumento da densidade do solo em B, comparado aos demais tratamentos, decorrente do pisoteio dos animais. O feijão caupi proporcionou maior retenção de água nas camadas abaixo de 0,10 m. Os maiores DMP e DMG foram encontratados em B, M, e M+B e os menores em C. O cultivo B apresentou maior percentagem da massa do solo distribuída em agregados >2,0 mm, em todas as camadas, enquanto que em C houve a menor proporção dos agregados maiores que 2,0 mm nas camadas abaixo de 0,10 m. M e M+B tiveram estabilidade de agregados intermediária entre B e C. Não houve diferença na resistência a penetração (RP) entre os tratamentos estudados, esta apenas variou com a profundidade e foi maior na segunda e terceira camadas ... / The physical and chemical soil attributes go hand in hand, and science seeks to improve the understanding about the interaction of these, aiming to include sustainability through conservation of soil and its natural resources, using the own soil system as a tool to reduce anthropogenic practices. The aim of this study was to evaluate the physical and chemical soil properties under different crops in autumn-winter established five years ago in no-tillage system and clarify the influence of these attributes on the grain yield of soybean crop and its root growth. The experiment was conducted on an Oxisol clay texture. Four treatments autumn-winter, were established, Brachiaria ruziziensis (B), maize (M), maize intercropped with B. ruziziensis (M+B) and cowpea (C) and in summer was grown soybeans. Samplings were carried out during soybean flowering, for the analysis of physics and chemistry, were also taken samples of soybean roots. At the end of the experiment proceeded soybean harvest to determine grain yield. There was a decrease in the macroporosity and an increase in bulk density of the soil in the B treatment compared to the other treatments, due to the animal trampling. The cowpea provided greater water retention in the layers below 0,10 m, due to the smaller influence of roots of this crop and higher microporosity in the soil. The largest Mean Geometric Diameter (MGD) and Mean Weight Diameter (MWD) were observed in treatments B, M, and M+B and the lowest values in C. Treatment B had higher percentage of soil mass distributed in aggregates > 2,0 mm in all layers, while in treatment C there was the lowest aggregate stability (> 2,0 mm) in the layers below 0.10 m. M and M + B had intermediate stability of aggregates between treatments B and C. There was no difference in resistence to penetration (RP) between the treatments, this only varied with depth and was higher in the second and third layer ...

Made available in DSpace on 2014-12-02T11:16:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-17Bitstream added on 2014-12-02T11:21:37Z : No. of bitstreams: 1 000791351.pdf: 7024955 bytes, checksum: b3dcc258f3f7c9123e489ba9e8e28b6d (MD5) / Neste trabalho pretende-se diagnosticar e analisar o manejo dos recursos vegetais hortícolas alimentares da agricultura tradicional da comunidade caiçara residente no interior e entorno do Parque Estadual da Serra do Mar (PESM)- Núcleo Picinguaba- situado no estado de São Paulo relacionando-os com a orientação e interferência na paisagem. Para tanto, busca-se, à luz da Etnoecologia Abrangente, por meio de ferramentas da Etnobotânica e da Antropologia, subsídio para a análise do modo de vida das populações considerando o uso e ocupação do solo assim como a inserção e importância de espécies alimentares, cultivadas e não-cultivadas, no dia-a-dia das pessoas. Foram obtidos dados em campo por meio da observação participante e com o uso de questionários e entrevistas estruturadas e semi-estruturadas. Utilizou-se o geopreocessamento a fim de se obter um mapa a partir de unidades de paisagem reconhecidas pelos agricultores correlacionando critérios êmicos de distinção da paisagem com aspectos fitossociológicos e de diversidade. Concluiu-se que o sistema de conhecimentos, crenças e sentimentos influenciam o manejo das espécies alimentares e das paisagens afetando diretamente a conservação e variabilidade de espécies de plantas e paisagens, ainda que haja pressão para substituições e impedimentos legais. A partir da argumentação de que é possível co-existir conservação de recursos naturais em locais onde habitam comunidades tradicionais tendo em vista seu modo de vida conservacionista, espera-se que este trabalho possa trazer contribuições para programas e políticas públicas de proteção às populações que têm sua cultura comprometida por restrições da legislação de uma UC e para conservação das espécies alimentares alvo do estudo / This paper aims to diagnose and analyze the management of food plants resources of traditional agriculture of caiçara community resident in and around the Serra do Mar State Park (PESM) - Picinguaba situated in the state of São Paulo relating them to management and interference in the landscape . To do that, we seek the light of Comprehensive Ethnoecology, through tools of ethnobotany and anthropology, allowing the analysis of the way of life of the people considering the use and occupation as well as the inclusion and importance of food species, cultivated and non-cultivated, day-to-day lives. Field data were obtained through participant observation and the use of questionnaires and structured and semi-structured interviews. We used the geoprocessing in order to obtain a map from landscape units recognized by farmers correlating emic criterion for distinguishing the landscape with phytosociological and diversity aspects. We can conclude that the system of knowledge, beliefs and feelings influence the management of food plants species and landscapes directly affecting the conservation and variability of plant species and landscapes, although there is pressure to substitutions and legal impediments. From the argument that it is possible to co -exist conservation of natural resources in places with traditional communities considering their conservationist way of life, it is expected that this work will bring contributions to public programs and policies to protect the people who have their culture compromised by restrictions in the laws of a Conservation Unit (UC) and to the conservation of targeted food plants of this study

Made available in DSpace on 2015-03-03T11:52:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-07-29Bitstream added on 2015-03-03T12:06:23Z : No. of bitstreams: 1 000811948_20160218.pdf: 119492 bytes, checksum: 1b8e70af25175908045fe43566b8c61d (MD5) Bitstreams deleted on 2016-02-18T10:00:24Z: 000811948_20160218.pdf,. Added 1 bitstream(s) on 2016-02-18T10:01:05Z : No. of bitstreams: 1 000811948.pdf: 619713 bytes, checksum: dc914320e284f5690f063a320e6781cd (MD5) / A soja é a oleaginosa mais importante cultivada no planeta. Dela são retirados inúmeros derivados, que compõem a alimentação humana e animal. Dentre os principais estão o farelo e o óleo que têm sua cotação influenciada pela razão demanda/produção no cenário mundial. Desde sua introdução no Brasil em 1882, a soja vem passando por um processo constante de melhoramento genético, o que permitiu que a cultura expandisse a área de cultivo que era basicamente a região Sul até a década de 70 para a região dos cerrados que corresponde ao Triângulo Mineiro, Mato Grosso do Sul, Mato Grosso, Goiás, Tocantins, sul do Maranhão, sul do Piauí e oeste da Bahia. Para um programa de melhoramento genético, a obtenção de estimativas de parâmetros genéticos é de grande importância, pois possibilita conhecer a magnitude dos efeitos que controlam o carácter além da possibilidade de predizer qual será o ganho com a seleção. O ganho genético para o melhorista tem grande importância, pois com os valores deste parâmetro pode-se efetuar alterações no critério seletivo adotado, visando adequar a população selecionada aos objetivos do programa de melhoramento. Avaliar as características agronômicas da soja e analisar todos os parâmetros ao mesmo tempo em função das informações coletadas durante o ensaio, se torna interessante quando o objetivo é selecionar genótipos superiores, uma vez que muitos fatores estão relacionados de maneira que seus diferentes efeitos são melhor interpretados se estudados em conjunto. A estatística multivariada permite identificar quais caracteres estão diretamente correlacionados com a produtividade de grãos e discriminar os genótipos levando em consideração a similaridade dos múltiplos caracteres avaliados, ajudando no processo seletivo. A análise, a descrição e a inferência são realizadas com base nas respostas simultâneas, valendo-se da estrutura de correlação ... / Soybean is the most important cultivated oilseed crop on the planet, it is extracted numerous derivatives that make up the human and animal food. Among the main ones are the bran and oil that have influence your quote according to the reason of demand and production on the world stage. Since its introduction in Brazil in 1882, the soybean has been undergoing a constant process of genetic breeding, which allowed the culture expand the area of cultivation which was basically South in the 70 years for the Cerrado region that corresponds to Triangulo Mineiro, Mato Grosso do Sul, Mato Grosso, Goias, Tocantins, Maranhao south, south west of Piaui and Bahia. For a breeding program, obtain estimates of genetic parameters is of great importance, as they allow to know the magnitude of the effects that control the character and the ability to forecast the gain with selection. The genetic gain for the breeder is very important, because with the values of this parameter can make changes to the selection criteria adopted in order to adjust the improved population for the objectives of the breeding program. Evaluate the agronomic characteristics of soybean and analyze all parameters at the same time in function on the information collected during the test becomes interesting when the goal is to select superior genotypes, since many factors are correlated so that their different effects are best interpreted if studied together. The Multivariate statistics allows to identify which characters are directly correlated with grain yield and discriminate the genotypes taking into account the similarity of multiple traits evaluated, helping in the selective process. The Analysis, description and inference are performed based on the simultaneous responses, taking advantage of the correlation structure between the variables. The objective of this study was to estimate genetic parameters in advanced soybean lines, identify characters directly and ...

Orientador: Leila Trevisan Braz / Banca: José branco de Miranda Filho / Banca: Renata Castoldi / Banca: Rinaldo Cesar de paula / Banca: Priscila Lupino Gratão / Resumo: Em programas de melhoramento genético, é usual a mensuração de vários caracteres com o objetivo de se praticar a seleção simultânea para alguns deles. Neste aspecto, a linhagem selecionada deve reunir uma série de atributos favoráveis capazes de se diferenciar de cultivares elites já estabelecidas no mercado em potencial produtivo e, ao mesmo tempo, satisfazer as exigências do consumidor. As linhagens desenvolvidas, quando plantadas em diferentes ambientes de cultivo, sofrem influência de fatores ambientais, em maior intensidade, sobre características quantitativas. Isto sugere que, nos programas de melhoramento genético de plantas, sejam realizados testes de cultivares em múltiplos locais, épocas e anos, a fim de se avaliar o comportamento dessas linhagens/cultivares frente às diferenças entre e dentro de ambientes, que caracteriza o estudo acerca da interação de genótipos com ambientes. Diante desse contexto, objetivou-se com o presente trabalho: a) verificar a eficiência de índices de seleção não paramétricos em selecionar linhagens de alface-crespa promissoras para o registro no Ministério da Agricultura Pecuária e Abastecimento, com base em diferentes caracteres, e estimar os ganhos genéticos com base nos índices de seleção; b) estimar a estabilidade e adaptabilidade genotípica de linhagens/cultivares de alface-crespa resistentes a Bremia lactucae em diferentes sistemas de cultivo e épocas em Jaboticabal-SP. O trabalho se dividiu em duas etapas, sendo a primeira o estudo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: - Genetic breeding programs typically measure several traits in order to simultaneously select for some of them. In this respect, the breeding line selected should combine a series of favorable attributes that set it apart from elite cultivars already established in the market in terms of yield potential, while also meeting consumer demands. When planted in different environments, the quantitative traits of the lines developed were more intensely affected by environmental factors. This suggests that plant breeding programs would benefit from testing cultivars in different locations, seasons and years to evaluate their behavior in relation to differences between and within environments, charactering a study of the interaction between genotypes and environments. As such, the present study aimed to: a) assess the effectiveness of non-parametric selection indices in selecting promising breeding lines of crispy endive lettuce for registration with the Ministry of Agriculture, Livestock and Supply, based on different characteristics, and estimate the genetic gains achieved with these indices; b) estimate the stability and adaptability of crispy endive lettuce lines/cultivars resistant to Bremia lactucae in different cultivation systems and seasons in Jaboticabal, São Paulo state (SP). The study was divided into two stages; the first involved analyzing nonparametric selection indices and genetic gains in six locations in São Paulo state, and the second consisted of estimating the stability and adaptability of the breeding lines studied using mixed models. The first experiment used a randomized block design and was carried out in areas belonging to lettuce growers in the municipalities of Monte Alto, São Simão, Salesópolis, Biritiba Mirim, Mogi das Cruzes and Aramina (SP), during the 2014 fall-winter season. Eight breeding lines of crispy ... (Complete abstract click electronic access below) / Doutor

Orientador: Maria Helena Moraes / Coorientador: Gessí Ceccon / Banca: José Eduardo Corá / Banca: Sergio Lazaro de Lima / Resumo: Os atributos físicos e químicos do solo caminham lado a lado, e a ciência busca aprimorar o entendimento a respeito da interação dos mesmos, visando contemplar a sustentabilidade pela conservação do solo e de seus recursos naturais, utilizando o próprio sistema solo como uma ferramenta para redução das práticas antrópicas. O objetivo desse estudo foi avaliar os atributos físicos e químicos do solo submetido a diferentes cultivos de outono-inverno estabelecidos há cinco anos em sistema de semeadura direta e esclarecer qual a influência desses atributos na produtividade de grãos da soja. O experimento foi conduzido em Latossolo Vermelho distroférrico de textura argilosa. Foram estabelecidos quatro tratamentos de outono-inverno, Brachiaria ruziziensis (B), milho (M), milho consorciado com Brachiaria ruziziensis (M+B) e feijão caupi (C) e no verão foi cultivado soja. Foram realizadas coletas de solo, durante o período de florescimento da soja, para as análises física e química, foram retiradas também amostras de raízes da soja. Ao final do experimento foi realizada a colheita da soja para determinar a produtividade de grãos. Houve redução da macroporosidade e aumento da densidade do solo em B, comparado aos demais tratamentos, decorrente do pisoteio dos animais. O feijão caupi proporcionou maior retenção de água nas camadas abaixo de 0,10 m. Os maiores DMP e DMG foram encontratados em B, M, e M+B e os menores em C. O cultivo B apresentou maior percentagem da massa do solo distribuída em agregados >2,0 mm, em todas as camadas, enquanto que em C houve a menor proporção dos agregados maiores que 2,0 mm nas camadas abaixo de 0,10 m. M e M+B tiveram estabilidade de agregados intermediária entre B e C. Não houve diferença na resistência a penetração (RP) entre os tratamentos estudados, esta apenas variou com a profundidade e foi maior na segunda e terceira camadas ... / Abstract: The physical and chemical soil attributes go hand in hand, and science seeks to improve the understanding about the interaction of these, aiming to include sustainability through conservation of soil and its natural resources, using the own soil system as a tool to reduce anthropogenic practices. The aim of this study was to evaluate the physical and chemical soil properties under different crops in autumn-winter established five years ago in no-tillage system and clarify the influence of these attributes on the grain yield of soybean crop and its root growth. The experiment was conducted on an Oxisol clay texture. Four treatments autumn-winter, were established, Brachiaria ruziziensis (B), maize (M), maize intercropped with B. ruziziensis (M+B) and cowpea (C) and in summer was grown soybeans. Samplings were carried out during soybean flowering, for the analysis of physics and chemistry, were also taken samples of soybean roots. At the end of the experiment proceeded soybean harvest to determine grain yield. There was a decrease in the macroporosity and an increase in bulk density of the soil in the B treatment compared to the other treatments, due to the animal trampling. The cowpea provided greater water retention in the layers below 0,10 m, due to the smaller influence of roots of this crop and higher microporosity in the soil. The largest Mean Geometric Diameter (MGD) and Mean Weight Diameter (MWD) were observed in treatments B, M, and M+B and the lowest values in C. Treatment B had higher percentage of soil mass distributed in aggregates > 2,0 mm in all layers, while in treatment C there was the lowest aggregate stability (> 2,0 mm) in the layers below 0.10 m. M and M + B had intermediate stability of aggregates between treatments B and C. There was no difference in resistence to penetration (RP) between the treatments, this only varied with depth and was higher in the second and third layer ... / Mestre

Trials were done on four Lachenalia cultivars (Romaud, Robyn, Rolina and Romelia) to improve flower quality and inflorescence stem length and to evaluate vase life, as these criteria are important for the cut flower grower. Flowering size bulbs were grown under five different shade nets (white 18%, green 40%, black 40%, black 55%, black 7O%) and in the open as a control. Under each shade net, bulbs were planted at a low planting density of two bulb diameters apart (56 bulbs/m2), as well as a high planting density of one bulb diameter apart (111 bulbs/m2). The effect (If the growth hormone gibberellic acid (GA3) on plant growth was investigated to determine if longer stems could be obtained. The plants were treated with gibberellic acid at 10 ppm and 0 ppm, which was applied as a foliar spray and as El bulb dip treatment. It is necessary to identify and describe specific flowering stages to be able to establish a standard rating system for Lachenalia vase life. The morphology of Lachenalia cultivar Romaud was described to determine the real succession of opening flowers on the inflorescence. The stages of 'first flower', 'full flower' and '50% wilt' were described. A high photosynthetically active radiation (PAR) measurement of 1250 µ.mol.m-2.s-1 in the control, resulted in the shortest inflorescence stem length of 13 cm for all four cultivars compared to the rest of the shade nets. The longest inflorescence stem length of 24 cm was produced for cultivars Rolina and Romelia by a low PAR of 400 µ.mol.m-2.s-1 under the black 70% shade net. The inflorescence stem length of all four Lachenalia cultivars tend to decrease to a minimum of 13 cm when average temperatures are 30oC and higher and to a maximum of 24 cm when temperatures are in the range from 24 to 27oC. A long vase life of 12 to 14 days for cultivar Rolina was observed under the green 40% and black 40% shade nets, compared to 10 to 11 days in the control. The green 40% shade produced a long vase life of 14 to 16 days for cultivar Romelia, compared to the 12 to 14 days in the control. Planting density significantly increased inflorescence stem length by about 2.5 cm and vase life by 2 days at the high planting density compared to the low planting density for all four cultivars. Inflorescence stem length for cultivars Romaud and Romelia increased significantly by 3 cm for both the GA3 foliar spray and bulb dip treatments. The number of flowers per inflorescence decreased significantly by about 3 to 5 flowers for cultivar Romaud and Romelia when GA3 was applied as a foliar spray or bulb dip treatment. A significant increase in vase life (2 days) of GA3 treated plants was observed. All four Lachenalia c:ultivars are suitable for cut flower production, as inflorescence stem lengths were either just below or above the 20 cm mark and vase life was longer than the five to six days required by the cut flower industry. / Dissertation (MSc (Agric): Horticulture)--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted

Please read the abstract in the section 00front of this document / Dissertation (M Inst Agrar (Plant Production: Agronomy))--University of Pretoria, 2007. / Plant Production and Soil Science / M Inst Agrar / unrestricted

Made available in DSpace on 2014-08-13T14:51:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-04-24Bitstream added on 2014-08-13T17:59:36Z : No. of bitstreams: 1 000776569.pdf: 1805226 bytes, checksum: 94588b2444e12e74c27a7e8e9682b188 (MD5) / A matéria orgânica do solo (MOS) apresenta um amplo conjunto de funções e tem sua quantidade e sua qualidade alteradas pelas diferentes possibilidades de rotações de culturas e manejo do solo. O objetivo deste trabalho foi avaliar os teores e a qualidade da matéria orgânica do solo em função de culturas em rotação sob Sistema Semeadura Direta (SSD). A pesquisa foi realizada em duas áreas conduzidas em SSD por no mínimo oito anos, com diferentes rotações de culturas, na Fazenda Experimental Lageado, Botucatu, SP. No experimento I, em um Latossolo Vermelho distroférrico de textura argilosa, as culturas em rotação foram sorgo granífero (Sorghum bicolor (L.) Moench), braquiária ruziziensis (Urochloa ruziziensis (R. Germ. & C. M. Evrard) Crins), e o consórcio de ambas no outono/inverno; milheto (Pennisetum glaucum L.), sorgo forrageiro (Sorghum bicolor (L.) Moench) e crotalária júncea (Crotalaria juncea L.), na primavera, como subparcelas, antecedendo a cultura da soja no verão. O segundo experimento foi conduzido em Nitossolo Vermelho distroférrico de textura muito argilosa. As parcelas foram constituídas pelas culturas de outono/inverno triticale (X Triticosecale Wittmack) e girassol (Helianthus annuus L.); e as subparcelas ... / Soil organic matter (SOM) plays major functions in agricultural soils, and its contents and quality can be altered by crop rotations and soil management. The aim of this study was to evaluate changes in soil organic matter as affected by crop rotations under no-tillage system. The study was carried out at two no-till managed field sites for at least eight years, in Botucatu, SP, Brazil. In the first experiment, the soil was a Rhodic Ferralsol, in which grain-sorghum (Sorghum bicolor (L.) Moench) and ruzigrass (Urochloa ruziziensis (R. Germ. and C. M. Evrard) Crins), single or intercropped in the fall/winter period, were the plots. Pearl millet (Pennisetum glaucum L.), forage sorghum (Sorghum bicolor (L.) Moench) and sunn hemp (Crotalaria juncea L.) were cropped in the spring, as subplots, before the summer crop (soybean). In the second experiment, the soil 4 was a Typic Rhodudalf under no-till since 2003 and the crop rotations studied were: triticale (X Triticosecale Wittmack) and sunflower (Helianthus annuus L.) as autumn-winter crops (plots); pearl millet, forage sorghum, sunn hemp and chiseling (performed in 2003 and 2009) in spring as subplots, before the summer crop (soybean). Organic matter humification degree (HLIF) was determined by laser-induced fluorescence spectroscopy (LIF) in soil samples collected from 0-0,10; 0,10-0,20; 0,20-0,40 and 0,40-0,60 m depths in April 2012. Soil aggregates stability was assessed from soil samples collected from 0-0,10 and 0,10-0,20 m depths in November 2012. The remaining soil organic matter assessments were carried out from samples collected in April 2013. Total organic carbon (TOC), total nitrogen (TN), particulate organic carbon (POC), and mineral associated organic carbon (MOC) contents were determined from soil samples collected from 0-0,10; 0,10-0,20; 0,20-0,40 and 0,40-0,60 m depths; soil microbial biomass C and N were determined from soil samples coll ...

Orientador: Juliano Carlos Calonego / Banca: Ciro Antonio Rosolem / Banca: Rodrigo Arroyo Garcia / Resumo: A matéria orgânica do solo (MOS) apresenta um amplo conjunto de funções e tem sua quantidade e sua qualidade alteradas pelas diferentes possibilidades de rotações de culturas e manejo do solo. O objetivo deste trabalho foi avaliar os teores e a qualidade da matéria orgânica do solo em função de culturas em rotação sob Sistema Semeadura Direta (SSD). A pesquisa foi realizada em duas áreas conduzidas em SSD por no mínimo oito anos, com diferentes rotações de culturas, na Fazenda Experimental Lageado, Botucatu, SP. No experimento I, em um Latossolo Vermelho distroférrico de textura argilosa, as culturas em rotação foram sorgo granífero (Sorghum bicolor (L.) Moench), braquiária ruziziensis (Urochloa ruziziensis (R. Germ. & C. M. Evrard) Crins), e o consórcio de ambas no outono/inverno; milheto (Pennisetum glaucum L.), sorgo forrageiro (Sorghum bicolor (L.) Moench) e crotalária júncea (Crotalaria juncea L.), na primavera, como subparcelas, antecedendo a cultura da soja no verão. O segundo experimento foi conduzido em Nitossolo Vermelho distroférrico de textura muito argilosa. As parcelas foram constituídas pelas culturas de outono/inverno triticale (X Triticosecale Wittmack) e girassol (Helianthus annuus L.); e as subparcelas ... / Abstract: Soil organic matter (SOM) plays major functions in agricultural soils, and its contents and quality can be altered by crop rotations and soil management. The aim of this study was to evaluate changes in soil organic matter as affected by crop rotations under no-tillage system. The study was carried out at two no-till managed field sites for at least eight years, in Botucatu, SP, Brazil. In the first experiment, the soil was a Rhodic Ferralsol, in which grain-sorghum (Sorghum bicolor (L.) Moench) and ruzigrass (Urochloa ruziziensis (R. Germ. and C. M. Evrard) Crins), single or intercropped in the fall/winter period, were the plots. Pearl millet (Pennisetum glaucum L.), forage sorghum (Sorghum bicolor (L.) Moench) and sunn hemp (Crotalaria juncea L.) were cropped in the spring, as subplots, before the summer crop (soybean). In the second experiment, the soil 4 was a Typic Rhodudalf under no-till since 2003 and the crop rotations studied were: triticale (X Triticosecale Wittmack) and sunflower (Helianthus annuus L.) as autumn-winter crops (plots); pearl millet, forage sorghum, sunn hemp and chiseling (performed in 2003 and 2009) in spring as subplots, before the summer crop (soybean). Organic matter humification degree (HLIF) was determined by laser-induced fluorescence spectroscopy (LIF) in soil samples collected from 0-0,10; 0,10-0,20; 0,20-0,40 and 0,40-0,60 m depths in April 2012. Soil aggregates stability was assessed from soil samples collected from 0-0,10 and 0,10-0,20 m depths in November 2012. The remaining soil organic matter assessments were carried out from samples collected in April 2013. Total organic carbon (TOC), total nitrogen (TN), particulate organic carbon (POC), and mineral associated organic carbon (MOC) contents were determined from soil samples collected from 0-0,10; 0,10-0,20; 0,20-0,40 and 0,40-0,60 m depths; soil microbial biomass C and N were determined from soil samples coll ... / Mestre

The most critical hurdle on the path to sustainable development in Africa and the rest of the so-called Third World is poverty, commonly manifested as food security. A number of factors threaten food security in Zimbabwe, and these include climate change, an unstable socio-political environment and economic depression. The major debates and initiatives on sustainable development often fail to focus on the eradication of poverty in southern Africa. As a result, the trade liberalisation programmes signed by African countries in economic partnership agreements leave smallholder farmers vulnerable to the influx of hybrid seed and genetically modified organisms (GMOs), which threaten local agro-biodiversity. This case study has shown that farmers select seed to plant for food as a result of various learning interactions they engage in, which include inter-generational knowledge transfer, farmer to farmer extension and external training by extension organisations and NGOs. A communities of practice (COPs) (Wenger, 2007) framework was used to gain an understanding of the learning interactions among farmers and their stakeholders in Nyanga and Marange COPs of small grain farmers in Manicaland Province, Zimbabwe, who have been working with Environment Africa (A regional NGO). A critical realist causal analysis was conducted to unravel the various causal factors influencing choice. A number of underlying structures and causal mechanisms were found to influence learning interactions and choices in these communities of practice, and they include ambivalence, which influences the changing domain and practice. Climate change, drought and risk were found to affect farmer practice, while power relations affect the community, its practice, domain, sponsorship and the learning interactions in the COPs. The political economy was also found to have a profound effect on the domain and practice. A space was found for the influence of capacity and knowledge sharing in participatory frameworks of the communities, implying that extension quality can be enhanced to promote locally adapted and diverse seed varieties for food security improvement. The study shows that a deeper understanding of the mechanisms influencing the context of teaching and learning provides a more refined insight into the learning interactions and choices of farmers. This, coupled with the social processes descriptors provided by Wildemeersch (2007) has given me a more detailed understanding of the nature of learning interactions influencing farmer choices.