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Leaf and associated soil samples from 15 locations in Quebec showed that grey tobacco contained less N, P, K, Ca, B, nicotine, total alkaloids, organic acids, fatty acids, but more Fe and Al than non-grey (normal) tobacco. Soils producing grey tobacco had less N, Ca, organic matter, a lower cation exchange capacity but more Cl. / Fe('55) fed to tobacco plants grown in soil known to produce grey tobacco was translocated to vascular and associated tissue in leaves. The grey disorder symptoms were duplicated in hydroponically grown plants. / In a two-year field study, grey tobacco had 20% less dry weight and 30% less leaf area. Relative growth rate and net assimilation rate decreased less rapidly during growth in grey than in non-grey tobacco. N and K content in leaves was lower in grey tobacco but higher in Fe and Mn. / The grey effect was decreased or eliminated in tobacco plants grown in pots with manure and lime. The leaf contents of Fe, Mn and Mg were associated with grade index ((CENTS)/kg) and dollar value/ha of tobacco. Fertilizer and manure reduced leaf Ca. Fertilizer alone increased the leaf content of N, P and K while manure increased leaf dry weight. The ratio of K/Ca and K/(Ca + Mg) increased with increasing levels of manure relative to each level of lime while the percent grey tobacco decreased dramatically.

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Made available in DSpace on 2014-06-11T19:22:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-07-30Bitstream added on 2014-06-13T20:28:26Z : No. of bitstreams: 1 mancuso_mac_me_botfca.pdf: 468949 bytes, checksum: da5909b1b01d8fee70d243a15e351d58 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O Brasil é o maior produtor mundial de café, sendo esse um dos mais importantes produtos agrícolas de exportação, gerando riquezas e divisas ao País. Com isso, a produção de plantas bem nutridas, através da utilização de fertilizantes, tornase cada vez mais importante. O Brasil é um dos maiores importadores mundiais de fertilizantes e o 4o maior consumidor dos mesmos. Só de KCl, em 2009, o Brasil consumiu cerca de 3,2 milhões de toneladas. Isso se deve a fatores como a extensa área cultivada, refletindo na dimensão da produção agrícola brasileira, as características dos seus solos muito pobres quanto aos macronutrientes K e P e a insuficiente produção doméstica de fertilizantes. Para diminuir a dependência nacional do K utilizado na agricultura, a pesquisa vem buscando opções para obtenção desse nutriente com base em minerais contidos em rochas brasileiras, especialmente mediante a moagem de rochas potássicas. Com isso, o presente trabalho teve como objetivo avaliar a eficácia de uma rocha fonolito moída em fornecer K para a cultura do café. Para tanto, o experimento foi desenvolvido em uma propriedade no município de Pirajú-SP, sendo conduzido nos anos agrícolas de 2008/09 e 2009/10. Os tratamentos foram duas fontes de K (KCl e rocha fonolito moída F2) e três doses (75, 150 e 300 kg ha-1 de K2O), correspondente à ½, 1 e 2 vezes a dose de K2O recomendada para a cultura, aplicadas em um cafezal cultivar... / Brazil is the largest coffee producer in the world, which it is one of the most important agricultural export products, generating wealth and currency to this country. Therefore, a well-nourished plants production by fertilizers use becomes more and more important. Brazil is one of the largest importers and the 4th consumer of fertilizers in the world. In 2009, Brazil consumed about 3.2 million tons of KCl only. This is due to factors such as the huge planted area, what it is reflected in the size of Brazilian agricultural production, the characteristics of their soils, which are very poor in relation of the macronutrients K and P, and the insufficient fertilizer domestic production. To reduce the national dependency of K used in agriculture, research has sought options to obtain this element based on Brazilian minerals contained in rocks, especially through the grinding of potassic rocks. Thus, this study aimed to evaluate the effectiveness of a crushed rock to provide potassium to coffee crop. The experiment was carried out in the crop seasons 2008/09 and 2009/10, in a farm placed in Piraju-SP. The experimental treatments consisted in two K sources (KCl and ground phonolite rock F2) and three doses (75, 150 and 300 kg ha-1 of K2O), corresponding to ½, 1 and 2 times the recommended dose of K2O for coffee, applied to the cultivar Mundo Novo plants and these were already productive, besides a control (without K application). The experiment was in a randomized block design, in a factorial scheme (2 x 3 + 1), with four replications. The most important evaluations were leaf contents of N, P, K, Ca, Mg, S and Si, grain contents of the... (Complete abstract click electronic access below)

Orientador: Rogério Peres Soratto / Banca: Dirceu Maximino Fernandes / Banca: Enês Furlani Junior / Resumo: O Brasil é o maior produtor mundial de café, sendo esse um dos mais importantes produtos agrícolas de exportação, gerando riquezas e divisas ao País. Com isso, a produção de plantas bem nutridas, através da utilização de fertilizantes, tornase cada vez mais importante. O Brasil é um dos maiores importadores mundiais de fertilizantes e o 4o maior consumidor dos mesmos. Só de KCl, em 2009, o Brasil consumiu cerca de 3,2 milhões de toneladas. Isso se deve a fatores como a extensa área cultivada, refletindo na dimensão da produção agrícola brasileira, as características dos seus solos muito pobres quanto aos macronutrientes K e P e a insuficiente produção doméstica de fertilizantes. Para diminuir a dependência nacional do K utilizado na agricultura, a pesquisa vem buscando opções para obtenção desse nutriente com base em minerais contidos em rochas brasileiras, especialmente mediante a moagem de rochas potássicas. Com isso, o presente trabalho teve como objetivo avaliar a eficácia de uma rocha fonolito moída em fornecer K para a cultura do café. Para tanto, o experimento foi desenvolvido em uma propriedade no município de Pirajú-SP, sendo conduzido nos anos agrícolas de 2008/09 e 2009/10. Os tratamentos foram duas fontes de K (KCl e rocha fonolito moída F2) e três doses (75, 150 e 300 kg ha-1 de K2O), correspondente à ½, 1 e 2 vezes a dose de K2O recomendada para a cultura, aplicadas em um cafezal cultivar... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract : Brazil is the largest coffee producer in the world, which it is one of the most important agricultural export products, generating wealth and currency to this country. Therefore, a well-nourished plants production by fertilizers use becomes more and more important. Brazil is one of the largest importers and the 4th consumer of fertilizers in the world. In 2009, Brazil consumed about 3.2 million tons of KCl only. This is due to factors such as the huge planted area, what it is reflected in the size of Brazilian agricultural production, the characteristics of their soils, which are very poor in relation of the macronutrients K and P, and the insufficient fertilizer domestic production. To reduce the national dependency of K used in agriculture, research has sought options to obtain this element based on Brazilian minerals contained in rocks, especially through the grinding of potassic rocks. Thus, this study aimed to evaluate the effectiveness of a crushed rock to provide potassium to coffee crop. The experiment was carried out in the crop seasons 2008/09 and 2009/10, in a farm placed in Piraju-SP. The experimental treatments consisted in two K sources (KCl and ground phonolite rock F2) and three doses (75, 150 and 300 kg ha-1 of K2O), corresponding to ½, 1 and 2 times the recommended dose of K2O for coffee, applied to the cultivar Mundo Novo plants and these were already productive, besides a control (without K application). The experiment was in a randomized block design, in a factorial scheme (2 x 3 + 1), with four replications. The most important evaluations were leaf contents of N, P, K, Ca, Mg, S and Si, grain contents of the... (Complete abstract click electronic access below) / Mestre

Thesis (MScFor)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Increases in woody plant density ('bush encroachment') reduce livestock production and biodiversity. By convention, soil moisture, soil nutrients, fire and herbivory are regarded as the principal factors governing the tree-grass ratio of savannas. An experiment with a completely-crossed design was employed to investigate woody seedling (Acacia me/lifera) recruitment near Kimberley, Northern Cape, South Africa, after fire and under conditions of maximum-recorded rainfall, nitrogen addition and grazing. The field experiment was repeated as a garden experiment to determine if the two experiments yield comparable results. Tree germination in the field was extremely low, probably due to below-average natural rainfall in plots that only received natural rain, and insufficient watering frequency in irrigated plots. As a result of low germination, none of the treatments (rain/nitrogen/fire/grazing) had a significant effect on tree recruitment in the field experiment. The duration of the experiment (2000/2001 growing season) was insufficient for the treatments to affect grass composition, although the high rainfall treatment and grazing exclusion significantly improved grass cover and height. The garden experiment showed that frequent watering, no nitrogen addition and grass clipping significantly enhanced tree germination and survival (termed 'recruitment'). There were also significant interactions among rain, nitrogen and grazing in their effects on tree recruitment. The effects of rain on tree recruitment were more pronounced under nitrogen supplementation and vice versa. Similarly, high rain and high nitrogen enhanced the effect of grazing on tree recruitment. It is inferred that above-average rainfall years with frequent rainfall events are required for mass tree recruitment. Tree seedlings can further benefit from space and resources which are made available through grass defoliation. Conversely, nitrogen enrichment improves the competitive ability of the fast-growing grasses relatively more than that of the N2-fixing tree component, thereby suppressing tree recruitment. In contrast to conventional wisdom that grazing alone causes encroachment, it is suggested that there are complex interactions between the abovementioned factors and 'triggering' events such as unusually high rainfall. Contrary to many claims that equilibrium models are inappropriate for explaining savanna dynamics, it was shown that consumer-resource theory has explanatory power for bush-grass dynamics of the savanna studied. The state-space approach that was used facilitated the understanding of savanna dynamics and enabled predictions about the system's response to perturbations. The applicability of consumer-resource theory to semi-arid nutrient-poor savannas confirmed the importance of resource competition in structuring natural systems. / AFRIKAANSE OPSOMMING: Toenames in die digtheid van houtagtige plante ('bosverdigting') verlaag veeproduksie en biodiversiteit. Volgens konvensie word grondvog, grondvoedingstowwe, vuur en beweiding beskou as die belangrikste faktore wat die boom-gras verhouding van savannas bepaal. 'n Volledig-gekruisde ("completely crossed") eksperiment is ontwerp om boomsaad-ontkieming (Acacia mellifera) naby Kimberley, Noord-Kaap, Suid- Afrika, te bestudeer na 'n brand en onder toestande van maksimum-aangetekende reënval, stikstof toevoeging en beweiding. Die veldeskperiment is herhaal as 'n tuineksperiment om vas te stel hoe resultate van die twee eksperimente vergelyk. Boomsaad-ontkieming was uiters laag in die veld, waarskynlik weens ondergemiddelde reënval in persele wat slegs natuurlike reënvalontvang het, en 'n te lae benattingsfrekwensie in die besproeide persele. As gevolg van lae ontkieming in die veldeksperiment, het geen behandeling (reënval/stikstof/brand/beweiding) boomsaad-ontkieming beduidend geaffekteer nie. Die duur van die eksperiment (2000/2001-groeiseisoen) was te kort vir die behandelings om grassamestelling te beïnvloed, alhoewel besproeiing en geen beweiding die grasbedekking en -hoogte betekenisvol verhoog het. Die tuineksperiment het getoon dat boomsaadontkieming en vroeë oorlewing (genoem 'vestiging') betekenisvol verhoog is deur gereëlde benatting, geen stikstof toevoeging en die sny van gras. Daar was ook beduidende interaksies tussen reën, stikstof en beweiding in hul invloed op boomvestiging. Die reënbehandeling het 'n groter uitwerking op boomvestiging gehad onder stikstoftoevoeging en vice versa. Hoë reënval en stikstoftoevoeging het ook die invloed van beweiding op boomvestiging versterk. Die afleiding is dat bogemiddelde reënvaljare met gereëlde reënbuie 'n vereiste is vir grootskaalse boomvestiging. Boomsaailinge kan verder voordeel trek uit die spasie en hulpbronne wat beskikbaar raak wanneer gras ontblaar word. Daarteenoor verhoog stikstofverryking die mededingendheid van die vinniggroeiende grasse meer as dié van die N2-bindende boomkomponent, met die gevolg dat boomvestiging onderdruk word. In kontras met die konvensionele veronderstelling dat beweiding opsigself bosverdigting veroorsaak, word voorgestel dat ingewikkelde interaksies plaasvind tussen die bogenoemde faktore en ander 'sneller-gebeurtenisse', soos buitengewoon hoë reënval. In teenstelling met baie aansprake dat ekwilibrium modelle ontoepaslik is om savanna-dinamika te verklaar, is getoon dat die verbruikers-hulpbron teorie ("consumer-resource theory") oor verklaringsvermoë beskik vir boom-gras dinamika van die savanna wat bestudeer is. Die staat-spasie ("state-space") benadering gebruik, het begrip van savanna-dinamika bevorder en voorspellings moontlik gemaak aangaande die sisteem se reaksie op versteurings. Die toepaslikheid van verbruikers-hulpbron teorie vir semi-ariede, nutriënt-arm savannas bevestig dat kompetisie vir hulpbronne 'n sentrale rol speel in die strukturering van ekologiese sisteme.