Cabbage is one of the most important and widely grown crops in KwaZulu-Natal (KZN). In cabbage production, no clear cropping methods exist (other than succession cropping) to allow the soil to recover its fertility status naturally after the harvested has crop absorbed nutrients from the soil. Succession cropping system is extensively practiced by cabbage farmers. Succession cropping is when a succeeding vegetable crop is planted immediately after harvesting the preceding crop. This does not allow soil fertility status to be balanced by soil microbes in an environmentally friendly approach. Instead, synthetic fertilizers are heavily used to rectify soil fertility status and these have negative impacts on the soil in the long term, followed by yield decline. However, the economic downturns and green environment awareness have caused researchers and some farmers to focus more on developing environmentally healthy crop production technologies. A priority in this study was to elucidate effects of cover crops-green manure as rotational crops in cabbage production. The experimental site is located at Cedara Research Station. In 2009, soil samples were taken from the top 30 cm of the soil profile, in a zigzag pattern in 5 m x 5 m grids for fertility analysis. Results were used to determine nutrient deficiencies, and blanket application of phosphorus and potassium followed according to each grid’s deficiency. The study was divided into two cycles, with each cycle consisting of season one and season two. The study was conducted over a two year period. Cycle one, season one, 2009/2010 (Dec-Mar): four treatments (sunn hemp: planted at 50 kg/ha seeding rate; forage sorghum: planted at 50 kg/ha seeding rate; mixture of sunn hemp-forage sorghum: each planted at 25 kg/ha seeding rate and control: cabbage planted at 30 cm within rows x 60 cm between rows) were used. The statistical design of the study was a 4x4 Latin Square experiment repeated twice in adjacent fields (347 m2 each) 6 m apart, with a total of 32 plots. Each experimental plot was 8.5 m x 9 m. Genstat Package, 9th Edition was used for data analysis. Standard cabbage production recommendations were followed in control treatments. Cabbage yield was determined in all control plots. Weed coverage percentages were determined in all four treatments. Cycle one, season two, 2010, (Apr-Aug): all 32 plots from season one were each split into four, in a Split Plot design, resulting in a total of 128 plots in both fields. Nitrogen was applied at four different levels: 0, 80, 160 and 240 kg N/ha. Standard cabbage production methods were followed again as in the control treatment in season one. Cover crops were replaced by planting cabbage. Cabbage was repeated in the control plots. Cabbage yield, cabbage leaf nutrients, soil nitrate and ammonium nitrate and soil carbon to nitrogen (C:N) ratio were measured. Cycle two, season one, 2010 (Sep-Dec): The same method in cycle one, season one was repeated. Cycle two, season two, 2010/2011, (Dec-Apr): The same method in cycle one, season two was repeated. Although in this study there was visibly a large amount of residues left over after the trial was harvested, the use of a tractor-drawn slasher was not very effective. The slashed material was not chopped into smaller pieces, as it would if a roll-chopper had been used. A tractor-drawn slasher was used because it is a tool available to many farmers. As a result, it was not a simple process to transplant seedlings mechanically, due to the amount of organic matter that was in the soil after it had been incorporated. The mechanical planter pulled off, removed and became blocked by the residues, and as a result it was not able to operate as it would in normal soils. The residues removed soil from the furrows and that caused seedlings to fall over as all the soil for the root system support had been moved by the planter and stuck residues. The planter had to be assisted by hand planting seedlings that were not properly planted mechanically. Hence, from the operational perspective, the choice of tools for chopping were not effective in this study and this is something to be considered in future studies, where it will be necessary to compare different tools for planting and cover crop incorporation into the soil. During the present study, soil N content in different plots had significant differences (P=0.05). The control showed high levels of total N content, but this was not related to the low yields exhibited by cabbage after cabbage at all levels of N. Since, where there were cover crops, the N content was low, this could mean that N was immobilized, compared to the cabbage treatments where plenty of N was available. Immobilized N is thus not available for leaching, polluting the environment. The yield of cabbage was significantly lowest in controls. The study showed that cover crop-green manure use has a positive effect in terms of yield improvement. The cabbage yields from the sunn hemp plots at a 0 kgN/ha were significantly different from the yield of cabbage planted following cabbage at 240 kgN/ha N. The study also showed that N is not the only yield determinant in cabbage production. Too much N has a tendency to suppress cabbage yields. The cover crop-green manures selected for this study were shown to be ineffective in suppressing weeds. This was true even though the weed coverage percentage in each of the cover crop-green manure plots was above 65%, except for the cabbage crop. This study did not separate different weeds, but the most dominant weeds were Amaranthus hybridus (pigweed), Galinsoga parviflora (gallant soldier), Bidens pilosa (common blackjack) and Cyperus esculentus (yellow nutsedge). These weeds were effectively controlled in the cabbage sole crop by the use of herbicides and mechanical weeding. The result of cover crop-green manures not suppressing weeds was significantly associated with the cover crop-green manure seeding rate. This study has been a starting point in the development of cover crops-green manure as rotational crops in cabbage production. It is concluded that cover crop-green manure (sunn hemp and forage sorghum) used in this study for vegetable (cabbage) production has proven to be successful in improving yields. Yields obtained from cover crop-green manure treatments were better than yields obtained from - conventional tillage methods for cabbage production (control). However, in cabbage, weed suppression and soil N content, failed to improve significantly in response to the cover crop green manures used. The high plant population density under a cover crop, combined with weed population, may lead to high uptake of soil N for plant growth, leaving less N in the soil and in the plant. In the sole cabbage crop, because of low competition, there was adequate uptake of N for plant growth and yet the crop was not exhaustive of soil N. Further research is required in the following areas: comparison of cabbage with other vegetable crops in response to the effect of the selected cover crops; comparison of mechanical weeding and herbicide use as means of controlling weeds during cover crop-green manure growth; identification of dominant weeds in the presence and absence of cover crops, and monitoring of soil water relations and other fertiliser effects. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Unintentional nitrogen (N) loss from agroecosystems produces greenhouse gases, induces eutrophication, and is costly for farmers; therefore, adoption of conservation agricultural management practices, such as no-till and cover cropping, has increased. This study assessed N loss via leaching, NH3 volatilization, N2O emissions, and N retention in plant and soil pools of corn conservation agroecosystems across a year. Three systems were evaluated: 1) an unfertilized organic system with cover crops Vicia villosa, Triticum aestivum, or a mix of the two; 2) an organic system with a Vicia cover crop employing three fertilization schemes (0 N, organic N, or a cover crop N-credit approach); 3) a conventional system with a Triticum cover crop and three fertilization techniques (0 N, urea N, or organic N). During cover crop growth, species affected N leaching but gaseous emissions were low across all treatments. During corn growth, cover crop and fertilizer approach affected N loss. Fertilized treatments had greater N loss than unfertilized treatments, and fertilizer type affected gaseous fluxes temporally and in magnitude. Overall, increased N availability did not always indicate greater N loss or yield, suggesting that N conserving management techniques can be employed in conservation agriculture systems without sacrificing yield.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The southwest region of Rio Grande do Sul (RS) state has widespread areas with sandy soils in the process of sandification. In the present study, we report the effect of different intercropping in blackberry plants on the soil recuperation and crop productivity. The experiment was conducted in São Francisco de Assis located in southwest region of the RS. The soil was a typical Psament with 60 g kg-1 clay and 0.5 g kg-1 organic matter in the top 0- 10 cm layer. The crops that were intercropped with blackberry were jack bean (Canavalia ensiformis) / oat (Avena strigosa) (JB-O); Brachiaria (Brachiaria decumbens) (BRA) and native grass (NG). The soil recuperation was measured by assessing the C and N stocks in the soil and biological indicators such as the enzymatic activity and soil fauna in relation to traditional grazing native grass (GNP). Results showed that intercropping of crops with blackberry improved soil biological conditions in relation to the GNP. Intercropping of JB-O with blackberry resulted in high dry matter production and C and N accumulation in shoots. Similarly, among the crops BRA appeared to be the crop that has potential to increase C and N stocks in the soils. This effect could be explained the rooting system of this grass. The presence of NG under blackberry helped to achieve average fruit yield and could be used as a strategy to establish the cultivation of blackberry in this region. Moreover, blackberry showed adaptation to the ecological conditions of the sandy soils and can be considered as an alternative crop for 1) recovering and reducing the outspread of sandification 2) as a possible source of income for the farmers of this region. / Na região sudoeste do Rio Grande do Sul (RS) existem extensas áreas com solos arenosos em processo de arenização. O objetivo deste estudo foi de avaliar o efeito de diferentes culturas intercalares a amoreira-preta sobre a recuperação de solo em processo de arenização e produtividade da cultura na região Sudoeste do RS, no município de São Francisco de Assis. O solo do experimento foi um Neossolo Quartzarênico típico com 60 g kg-1 de argila e 0,5 g kg-1 de matéria orgânica na camada de 0-10 cm. Os tratamentos avaliados nas entrelinhas da amoreira-preta foram os seguintes: feijão-de-porco (Canavalia ensiformis)/aveia preta (Avena strigosa) (FP-AP); Brachiaria (Brachiaria decumbens) (BRA); e campo nativo (CN). A recuperação do solo no pomar foi medida através da avaliação da recuperação dos estoques de C e N no solo e de indicadores biológicos como, a atividade enzimática e a fauna do solo em relação ao campo nativo sob pastejo tradicional (CN-T). Os tratamentos FP-AP, BRA e CN nas entrelinhas da amoreira-preta resultaram em melhora das condições biológicas do solo em relação ao CN-T. A combinação de feijão-de-porco e aveia-preta nas entrelinhas da amoreirapreta apresentou maior produção de matéria seca da parte aérea e acúmulo de C e N. A BRA foi a espécie que se destacou quanto a capacidade de promover o aumento do estoque de C e N no solo na entrelinha da amoreira-preta. Efeito esse devido possivelmente ao sistema radicular agressivo desta gramínea. A permanência do CN nas entrelinhas da amoreira-preta, além de permitir a obtenção de média produtividade de frutos, se apresenta como uma alternativa para a redução no custo de implantação e condução do pomar com essa espécie frutífera na região dos solos arenosos do sudoeste do RS. A amoreira-preta apresentou adaptação às condições edafoclimáticas dos solos arenosos do sudoeste do RS, podendo ser considerada como alternativa para a recuperação e redução do avanço das áreas arenizadas e também como uma possibilidade de fonte de renda para o produtor rural desta região do estado.

Made available in DSpace on 2014-06-11T19:30:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-06-05Bitstream added on 2014-06-13T20:40:23Z : No. of bitstreams: 1 arroyogarcia_r_dr_botfca.pdf: 1117377 bytes, checksum: 640c0531b51ae26f4c6122ba741bb333 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O manejo inadequado do solo ocasiona a formação de camadas compactadas que prejudicam o desenvolvimento radicular das plantas, diminuindo a disponibilidade de água e nutrientes, enquanto que o acúmulo de carbono pode melhorar a qualidade do solo. Em sistemas com semeadura direta (SSD), com a menor mobilização do solo, pode-se usar, em rotação, plantas com sistema radicular vigoroso, capaz de crescer em condições adversas. Este trabalho teve como objetivo avaliar a ação de espécies de cobertura, gramíneas e uma leguminosa, em rotação com a cultura da soja, nos atributos físicos de um Latossolo, no acúmulo de carbono, nas diferentes frações da matéria orgânica e na produção da soja, em semeadura direta, ao longo de três anos. O experimento foi conduzido em um Latossolo Vermelho distroférrico de textura argilosa, na Fazenda Experimental Lageado, Unesp/Botucatu, nos anos agrícolas de 2006/2007, 2007/2008 e 2008/2009. No outonoinverno foram estabelecidas parcelas com braquiária (Brachiaria ruziziensis), sorgo granífero (Sorghum bicolor) e sorgo consorciado com braquiária. Na primavera, foram cultivados, em subparcelas, milheto (Pennisetum glaucum), cober crop [Sorghum bicolor (L.) Moench x Sorghum sudanense Piper Stapf], crotalária (Crotalaria juncea) ou pousio. A soja foi cultivada como safra de verão. Em março do primeiro ano foram retiradas amostras para caracterização da área experimental. Após o manejo das espécies cultivadas na primavera, no primeiro e terceiro ano, foram retiradas amostras indeformadas nas camadas de 0-5; 7,5-12,5; 15-20; 27,5-32,5 e 47,5-52,5 cm para determinação da densidade do solo, porosidade e curva de retenção de água no solo. Nas mesmas épocas, a estabilidade de agregados foi avaliada em amostras coletadas nas camadas de 0-5 e 5-10 cm. No terceiro ano do experimento, o intervalo hídrico ótimo (IHO) foi determinado... / Compacted layers resulting from inappropriate soil management may impair root growth, thus decreasing water and nutrient acquisition by crops. Conversely, soil quality is improved with soil carbon accumulation. In areas under no-till, crop rotation with plants with vigorous root systems may alleviate soil compaction, as well as increase soil carbon. In this experiment the effects of cover crops on soil physical properties, carbon accumulation, organic matter quality and soybean production under no-till in a compacted soil were studied for three years. The experiment was conducted on a clayey Rhodic Ferralsol, Lageado Experimental Farm, Unesp/Botucatu, in 2006/2007, 2007/2008 and 2008/2009. Congo grass (Brachiaria ruziziensis), grain sorghum (Sorghum bicolor) and a mix of both were cropped during fall-winter. Then, in the spring, pear millet (Pennisetum glaucum), cober crop [Sorghum bicolor (L.) Moench x Sorghum sudanense Piper Stapf] and indian hemp (Crotalaria juncea) were cropped and a treatment under fallow was set on sub-plots. Soybean was cropped as a summer crop. In March of the first year, samples were taken for characterization of the area. Right after spring crops were chemically desiccated in 2006 and 2008, undisturbed soil samples were taken from the layers 0-5; 7.5-12.5; 15-20; 27.5-32.5 and 47.5-52.5 cm to determine bulk density, porosity and water retention curve. At the same time, samples taken from the depths 0-5 and 5-10 cm were used to determine aggregate stability. In the third year, least limiting water range (LLWR) was evaluated in the 7.5-12.5 and 27.5-32.5 cm soil layers. Organic matter characterization was done in the third year, in the depths of 0-5 and 5-10 cm. Roots of spring crops were sampled in the layers 0-5; 5-10; 10-20; 20-40 and 40- 60 cm, one day before chemical desiccation in all growing seasons. Soybean roots were sampled in the same depths at R2 each... (Complete abstract click electronic access below)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The inclusion of cover crops in agricultural production systems has received attention for the ability to improve the multifunctionality of the soil. In order to improve soil structure and soil physical-hydric properties, especially soil water infiltration, the objective of this study was: (a) to evaluate the effect of different species of winter cover crops on soil physical properties and (b) to verify the relationship between punctual methods for the evaluation of water infiltration in the soil and the infiltration of water with natural rainfall on plot scale. For the first study the systems studied were: oat and vetch (AE) consortium, oat and turnip (AN), spontaneous vegetation (VE) and bare soil (SD). Soil samples with undisturbed structure were collected in the layers of 0 - 0,05; 0,05 - 0,1; 0,1 - 0,2 and 0,2 - 0,3 m to measure bulk density (DS), total porosity (Pt), macroporosity (Mac), microporosity (Mic), saturated soil hydraulic conductivity (Ksat) and permeability to air (Ka). Soil aggregation was also evaluated in the layers of 0 - 0.05 and 0.5 - 0.1 m. Soil water infiltration was determined by the concentric double ring method. For the second study, three treatments were used in the first study to determine the rate of stable infiltration of soil water (TIE) by the Cornell infiltrometer, double ring infiltrometer and infiltration in natural rainfall events. The results indicate that after the cultivation of winter cover crops, there are no changes in the physical properties evaluated, but there is evidence of improved water infiltration in the soil and the continuity and pore diameter in the treatments with cover crops. The TIE determined by the Cornell infiltrometer and double ring infiltrometer method is overestimated from 1.8 to 2.2 times that of natural rainfall. / A inclusão de plantas de cobertura em sistemas de produção agrícola tem recebido atenção pela habilidade de melhorar a multifuncionalidade do solo. Com vistas a melhoria da estrutura do solo e de propriedades físico-hídricas do solo, principalmente da infiltração de água no solo, objetivou-se com este trabalho: (a) avaliar o efeito de diferentes espécies de plantas de cobertura de inverno em propriedades físico-hídricas do solo e (b) verificar a relação entre métodos pontuais de avaliação da infiltração de água no solo com a infiltração de água com chuva natural em escala de parcela. Para o primeiro estudo os sistemas estudados foram: consorciação de aveia e ervilhaca (AE), consorciação de aveia e nabo (AN), vegetação espontânea (VE) e solo desnudo (SD). Amostras de solo com estrutura preservada foram coletadas nas camadas de 0 - 0,05; 0,05 - 0,1; 0,1 - 0,2; 0,2 - 0,3 m para avaliações da densidade do solo (Ds), porosidade total (Pt), macroporosidade (Mac), microporosidade (Mic), condutividade hidráulica do solo saturado (Ksat) e permeabilidade ao ar (Ka). Avaliou-se também a agregação do solo nas camadas de 0 - 0,05 e 0,5 - 0,1 m. A infiltração de água no solo foi determinada pelo método de duplo anel concêntrico. Para o segundo estudo foram utilizados três tratamentos do primeiro estudo para determinação da taxa de infiltração estável de água no solo (TIE) pelos métodos do infiltrômetro de Cornell, duplo anel concêntrico e a infiltração em eventos de chuva natural. Os resultados indicam que após um cultivo de plantas de cobertura de inverno ainda não são observadas alterações nas propriedades físicas avaliadas, porém há indícios de melhoria da infiltração de água no solo e na continuidade e diâmetro de poros nos tratamentos com plantas de cobertura. A TIE determinada pelo método de duplo anel concêntrico e infiltrômetro de Cornell é superestimada de 1,8 a 2,2 vezes em relação a determinada com chuva natural.

Made available in DSpace on 2014-06-11T19:33:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-06-27Bitstream added on 2014-06-13T20:05:52Z : No. of bitstreams: 1 marcelo_av_dr_jabo.pdf: 1194015 bytes, checksum: 68c9171ad52d863ef75fe8bb9b03c925 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Em sistema de semeadura direta, os resíduos das culturas de entressafra são utilizados para protegerem a superfície do solo dos agentes erosivos e promoverem a ciclagem de nutrientes. O objetivo desse trabalho foi avaliar o efeito de sequências de culturas na quantidade, qualidade, decomposição e liberação de nutrientes dos resíduos vegetais de culturas de entressafra, bem como a cobertura do solo proporcionada pelos resíduos, na fertilidade do solo, nas frações particulada e associada aos minerais de C, nas substâncias húmicas do solo e na produtividade de milho e soja cultivados no verão, em região de clima tropical. O experimento foi conduzido em Jaboticabal, SP (48°15’22’’ W e 21°18’58’’ S), em um Latossolo Vermelho eutrófico. O delineamento experimental foi em faixas, com três repetições. Os tratamentos foram constituídos pela combinação de três sequências de culturas de verão (rotação soja-milho, monocultura de milho e monocultura de soja) com sete culturas de entressafra (milho, sorgo, girassol, crotalária, guandu, nabo forrageiro e milheto). O experimento foi iniciado em 2002 e o presente estudo se refere aos anos agrícolas 2008/2009 e 2009/2010. Avaliaram-se as quantidades de matéria seca e acúmulo de N, P, K, Ca, Mg e S pelas culturas de entressafra, bem como a dinâmica de decomposição e liberação dos nutrientes, por meio da utilização de sacolas de decomposição, com os seguintes períodos de avaliação: 15, 30, 60, 120 e 180 dias. A cobertura do solo foi avaliada após o manejo e ao final de cada ano agrícola. Amostras de solo foram coletadas nas camadas 0-10, 10-20 e 20-30 cm de profundidade em duas ocasiões, antes da semeadura das culturas de entressafra, em março, e de verão, em outubro, nos anos de 2008 e 2009. As amostras de solo foram submetidas às análises químicas para determinação dos teores... / In no-tillage system, the offseason crops residues are expected to maintain the soil covered in order to control soil erosion and to promote the nutrients cycling. The objective of this study was to evaluate the offseason crops dry matter quality and production, soil cover, residues decomposition and nutrient release and their effects on soil fertility, C content of humic substances, particulate and mineral associated organic matter fractions and summer maize and soybean yield. A field experiment has been carried out on a Rhodic Eutrudox at Jaboticabal, SP, Brazil (48°15’22’’ W and 21°18’58’’ S). A randomized split-block design with three replications was used. The treatments were the combination of three summer crops sequences (soybean-corn rotation, monoculture of corn and monoculture of soybean) with seven offseason crops (maize, grain sorghum, sunflower, sunn hemp, pigeon pea, oilseed radish and pearl millet). The cultivations started in 2002 and this study is related to 2008/2009 and 2009/2010 growing seasons. The offseason crops dry matter production and N, P, K, Ca, Mg and S accumulations were evaluated at management moment. The period of time to measure the residue decomposition and the nutrient release was 15, 30, 60, 120 and 180 days, using litter bags. The soil cover was evaluated after the offseason crops management and at the end of each growing season. The soil was sampled at 0-10, 10-20 and 20-30 cm soil depths in two occasions, before the offseason crops sowing, at March, and before the summer crops sowing, at October, in 2008 and 2009. Total organic C, pH, P, K, Ca, Mg and H+Al were determined in each soil samples. The soil samples obtained on October at 0-10 cm were submitted for physical and chemical organic matter fractionation, for particulate, mineral-associated, humic acid, fulvic acid and humin C content determination. The summer monoculture... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:33:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-20Bitstream added on 2014-06-13T21:06:47Z : No. of bitstreams: 1 beraldo_jmg_dr_jabo.pdf: 1719744 bytes, checksum: a27050b0770082469a896d7df06651eb (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O sistema de semeadura direta (SSD) proporciona melhores condições físicas do solo favorecendo o armazenamento de água no solo (ARM). A hipótese do trabalho foi que o Latossolo Vermelho argiloso, em sequências de culturas de verão e inverno sob SSD afeta o ARM em decorrência da modificação nos atributos físicos do solo e que o tensiômetro de punção digital (TDig) pode ser usado para medir o potencial mátrico da água no solo. Os objetivos foram avaliar o ARM e os atributos físicos do solo em sequências de culturas de verão e de inverno sob SSD e medir o potencial mátrico da água no solo por meio do tensiômetro de mercúrio e do TDig. O delineamento foi em blocos, com três repetições, no esquema em faixas. Os tratamentos foram constituídos por três sequências de culturas de verão (rotação soja/milho e monocultura de milho e soja) e sete culturas de inverno (milho, girassol, nabo forrageiro, milheto, guandu, sorgo e crotalária). Foram instalados tensiômetros nas camadas de 0,2; 0,4 e 0,6 m. Foi determinada a densidade do solo, a distribuição de poros por tamanho nas camadas de 0-0,1 e 0,1-0,2 m e a infiltração de água na superfície do solo. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey. O TDig pode ser usado para avaliar o potencial mátrico da água no solo. O ARM não diferiu entre as sequências de culturas de verão e nas culturas de inverno houve diferença, principalmente após período de menor disponibilidade hídrica. A densidade e a porosidade do solo não foram influenciadas pelas culturas de verão e inverno. O diâmetro de poros entre 0,075 - 0,05 e 0,03 - 0,0375 mm na camada de 0,0-0,1 m diferiu entre as sequências de verão. A distribuição de poros por tamanho não foi influenciada pelas sequências de culturas de inverno. A maior infiltração de água no solo ocorreu na parcela sob monocultura de soja / No tillage system provides soil physical properties improvements, and soil water storage. The hypothesis of this study was that a Red Latosol (Oxisol), in summer and winter crops sequences under no-tillage system, can have its soil water storage influenced by changes in soil physical properties and digital tensiometer can be used to measure soil water matric potential. This study aimed to measure the soil matric potential using both mercury and digital tensiometers and to evaluate the soil water storage and physical properties on summer and winter crops sequences under no-tillage system. A completely randomized block was designed with three replications on a strips plan. The treatments were the combination of three summer crops sequences (soybean/maize rotation, corn and soybean monocultures) and seven winter crops (maize, sunflower, oilseed radish, millet, pigeon pea, sorghum and sunn hemp). Tensiometers were installed at a depth of 0.20; 0.40; 0.60 meters. Bulk density and pores distribution curves were determined from layers 0-0.1 and 0.1-0.2 depth and water infiltration at the soil surface. The data were submitted to variance analysis and means were compared by the Tukey test. The hypothesis was confirmed, therefore digital tensiometer can be used to measure soil water matric potential. The results showed no difference regarding soil water storage in summer crops sequences, especially after a period associated with lower water availability. Soil porosity and bulk density were not influenced by summer and winter crops sequences. The results indicated that the pores with diameter between 0,075 - 0,05 e 0,03 - 0,0375 mm from layer 0-0.1 m differed on summer crops sequences. No difference was observed by pores distribution curves between summer and winter crops sequences. The largest water infiltration occurred under the soybean monocultures plot

Made available in DSpace on 2014-06-11T19:23:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-07-31Bitstream added on 2014-06-13T20:10:45Z : No. of bitstreams: 1 marcelo_av_me_jabo.pdf: 629434 bytes, checksum: c8c52d678b56187ddb8c2e98eeffc55d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A rotação de culturas em sistema de semeadura direta (SSD) promove vários benefícios ao sistema, pois os resíduos das culturas, ao se decomporem, podem alterar os atributos químicos do solo e, como conseqüência, influenciarem a cultura em sucessão. O presente trabalho teve como objetivo avaliar os efeitos de culturas de inverno nos atributos químicos do solo, no estado nutricional e na produtividade das culturas de soja, milho e arroz, cultivadas no verão em SSD. O experimento foi realizado no município de Jaboticabal, SP, em Latossolo Vermelho eutrófico. O delineamento experimental utilizado foi de blocos casualizados com três repetições no esquema em faixas. Os tratamentos foram constituídos pela combinação de quatro seqüências de culturas de verão (monoculturas de milho e de soja e as rotações soja/milho e arroz/feijão/algodão) com sete culturas de inverno (milho, girassol, nabo forrageiro, milheto, guandu, sorgo e crotalária). Após o manejo das culturas de inverno e antes da semeadura das culturas de verão do ano agrícola 2006/2007, foram coletadas amostras de solo nas camadas de 0-2,5; 2,5-5,0; 5-10; 10-20 e 20-30 cm. Nas amostras de solo, foram determinados: matéria orgânica (MO), pH, P (resina), K, Ca, Mg, H+Al e calculados CTC e V. Nas culturas de verão, coletaram-se amostras foliares para a determinação das concentrações foliares de N, P, K, Ca, Mg, S, B, Cu, Fe, Mn e Zn. A produtividade das culturas de verão foi avaliada. Foram observados no solo, maiores teores de P após nabo forrageiro e crotalária e menores teores de MO após milho, girassol e guandu no inverno. O SSD apresentou gradientes de fertilidade ao longo do perfil para todos os atributos químicos avaliados... / The crop rotation practice in no-tillage system promotes lots of benefits to the system. The crop residues can change the soil chemical attributes, consequentially influencing the performance of following crops. The objective of this work was to evaluate the effects of winter crops on the soil chemical attributes, nutritional state and yield summer crops (soybean, corn and rice) in no-tillage system. A field experiment has been carried out on a eutrophic Red Oxisol at Jaboticabal, SP, Brazil. A completely randomized block design with three replications was used, in strips. The treatments were the combination of four summer crops sequences (corn and soybean monocultures, rotation soybean/corn and rotation rice/bean/cotton) with seven winter crops (corn, sunflower, oilseed radish, millet, pigeon pea, sorghum and sunn hemp). After the winter crops management and before the summer crops sowing at the crop season 2006/2007, the soil was sampled at 0-2.5, 2.5-5.0, 5-10, 10-20 and 20-30 cm soil depths. Organic matter, pH, P, K+, Ca+2, Mg+2, H+Al were determined, and cation capacity exchange and bases saturation values were calculated in each soil samples. The N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn uptake were determined in summer crops. Also, the summer crops yield was obtained. In the soil, the oilseed radish and sunn hemp provide the highest P contents and corn, sunflower and pigeon pea provide the lowest organic matter contents. The no-tillage system showed gradient of fertility in the soil profile. The soybean (rotation soybean/corn) showed lower S uptake after corn and sorghum. The soybean (monoculture) showed higher N, P and S uptake after oilseed radish and sunn hemp. In the corn, Zn uptake were lower after oilseed radish. The oilseed radish and sunn hemp provides the highest soybean yield. In the corn, the highest yields were observed after oilseed radish, millet and pigeon pea. The sorghum provides suppressor effect on the rice yield.

Orientador: Ciro Antonio Rosolem / Banca: Dirceu Maximono Fernandes / Banca: Salatier Buzetti / Banca: Julinano Carlos Calonego / Banca: Gedi Jorge Sfredo / Resumo: As espécies utilizadas em sistemas de rotação de culturas comportamse de maneira diferente quanto à absorção e ciclagem de nutrientes. Além disso, a absorção de nutrientes é influenciada pelas propriedades físicas do solo, capazes de modificar o crescimento e desenvolvimento radicular. O presente trabalho teve como objetivo estudar a ciclagem de nutrientes em três sistemas de rotação de culturas, relacionando-a à atividade radicular da braquiária e sorgo, em sistema de semeadura direta, escarificado (SDCE) e sem escarificação (SDSE), em Nitossolo Vermelho de textura argilosa na cidade de Botucatu-SP. Além das plantas de cobertura também se avaliou a atividade radicular das culturas do milho e da soja. O sistema de rotação foi implantado na safra de 2005/2006 como segue: (1) milheto / soja / sorgo / milho / sorgo/ soja; (2) milheto / soja / braquiária / milho / braquiária / soja e (3) milheto / soja / mamona + braquiária / milho / mamona + braquiária / soja. O delineamento experimental foi o de blocos ao acaso com quatro repetições em parcelas subdivididas. A condução do experimento deu-se por dois anos agrícolas (2006/2007; 2007/2008) para possível observação de algum efeito acumulativo dos tratamentos. A atividade radicular das plantas de cobertura (novembro 2006), do milho (fevereiro 2007) e da soja (dezembro 2007) foi avaliada indiretamente, usando-se rubídio como marcador. Aplicou-se 3 mL da solução de nitrato de rubídio no solo com cateter, a 0,05; 0,10; 0,20, 0,40 e 0,60 m de profundidade e a 0,11 e 0,22 m de distância da planta de referência. Decorrido 4 dias da aplicação, coletou-se as respectivas partes aéreas das plantas, as quais foram secas, moídas e digeridas por via úmida para determinação do teor de rubídio em absorção atômica. Também foram analisadas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract : The species used in crop rotation systems differ in nutrient absorption and cycling. Moreover, nutrient absorption is influenced by soil physical properties, which may affect root growth and its development. The present research had as objective to investigate nutrient cycling in three crop rotation systems and its relation to root activity of Brachiaria and sorghum in no tillage system, with and without chiselling. The experiment was carried out in Botucatu, SP, Brazil, in a Red Nitosol, with clay texture. The rotation system was implemented in 2005/2006 and carried out for two growing seasons (November of 2006 and 2007). Crop rotation systems were: (1) Pearl millet / soybean / sorghum / maize / sorghum / soybean; (2) Pearl millet / soybean / Brachiaria / maize / Brachiaria / soybean and (3) Pearl millet / soybean / Brachiaria + castor bean / maize / Brachiaria + castor bean / soybean. The experimental design was the completely randomized block with split-plots and four replications. Root activity was evaluated for either cover crops or maize and soybean. Root activity of cover crops (November of 2006 and 2007), maize (February of 2007) and soybean (December of 2007) was indirectly evaluated, using Rubidium as marker. The solution of 3 mL of rubidium nitrate was applied in soil with a catheter, at 0.05, 0.10, 0.20, 0.40 and 0.60 m depths and at 0.11 and 0.22 m away from the plant in question. The respective shoots were collected, dried, grounded and submitted to humid digestion 4 days after the application to evaluate rubidium level through atomic absorption. Chemical characteristics and soil penetration resistance were also evaluated at 0.00-0.05, 0.05-0.10, 0.10-0.20, 0.20-0.40 and 0.40-0.60 m depths in the respective growing seasons. According to Rb levels observed in dry matter, the highest... (Complete abstract click electronic access below) / Doutor

Made available in DSpace on 2014-08-20T13:25:38Z (GMT). No. of bitstreams: 1 dissertacao_rafaela_castro.pdf: 3855009 bytes, checksum: 0202984a6e8b9497e74ec1015cf46aef (MD5) Previous issue date: 2012-06-26 / The Candiota region has the largest coal reserve in Brazil, known as the Big Candiota deposit. In this locality the coal lies near the surface, being open-pit mining. This method of extraction involves removing the horizons A and / or B of the original soil, followed by removal of rocks with subsequent replacement of sterile armholes open. The sterile are leveled by bulldozer and is the replacement of topsoil original, finalizing the construction process from the ground. This process entails a large compression generated by intense and repeated traffic of heavy equipment over the area, restricting the establishment of vegetation for long periods. The impacts caused by the topographic reconstruction of the area are reflected in soil physical built, being directly related to the structure, being the density values and high disproportionality between micro and macropores the first negative effects to be observed. The use of plants that act as soil decompressor is an important strategy in recovering the structural quality of soil. The aim of the study was to analyze the potential of differentcover crops on reclamation by coal mining, through the determination of physical parameters of soil built over time. Treatments were analyzed with perennial grasses of summer, implanted in November / December 2003: T1 - Hemártria (Hemarthria altíssima), T4 - Pensacola (Paspalum notatum), T5 - Grama Tifton (Cynodon dactilon), T7- Braquiária brizanta (Brachiaria brizantha). As a control the ground built without cover crops was used SCSP, in order to observe the action of the plants in the recovery of built soil attributes. As general conclusions, after six years of experiment, the initial recovery of physical indicators of built soil was observed, proving the efficiency of perennial grasses to rehabilitate structure of soil built along the time. / A Região de Candiota concentra a maior reserva carbonífera brasileira, conhecida como a jazida Grande Candiota. Nesta localidade o carvão encontra-se próximo à superfície, sendo minerado a céu aberto. Este método de lavra envolve a retirada dos horizontes A e/ou B do solo original, seguida de remoção das rochas, com posterior reposição dos estéreis nas cavas abertas. Os estéreis são nivelados por trator de esteira e há a reposição da camada superficial do solo original, finalizando o processo de construção do solo. Este processo acarreta em uma grande compactação, gerada pelo tráfego intenso e repetido de equipamentos pesados sobre a área, podendo restringir o estabelecimento da vegetação por longos períodos. Os impactos causados pela recomposição topográfica da área refletem-se nos atributos físicos do solo construído, estando diretamente relacionados à estrutura, sendo os primeiros efeitos negativos a serem observados os valores de densidade elevados e a desproporcionalidade entre micro e macroporos. O uso de plantas que atuam como descompactadoras do solo constitui-se importante estratégia na recuperação da qualidade estrutural de solo. Tendo em vista o exposto, o objetivo geral do trabalho foi analisar o potencial de diferentes plantas de cobertura na recuperação de áreas degradadas pela mineração de carvão, através da determinação de parâmetros físicos do solo construído, ao longo do tempo. Foram analisados os tratamentos com gramíneas perenes de verão, implantadas em novembro/dezembro de 2003: T1 - Hemártria (Hemarthria altíssima), T4 - Pensacola (Paspalum notatum), T5 - Grama Tifton (Cynodon dactilon), T7- Braquiária brizanta (Brachiaria brizantha). Como testemunha usou-se o solo construído sem plantas de cobertura SCSP, no intuito de observar a ação das plantas na recuperação dos atributos do solo construído. Como conclusões gerais pode-se dizer que após seis anos de execução do experimento observa-se a recuperação inicial dos indicadores físicos do solo construído, se comprovando a eficiência das gramíneas perenes em recuperar a estrutura dos solos construídos ao longo do tempo. Palavras