Ph. D.

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No description available.

No description available.

The purpose of the study was to determine the effect of four salt concentrations and four acid levels of soil solution on the germination of Quercus emoryi and Robinia neo-mexicana seeds, and to study the effects of the cation concentration changes in solution (Na, Ca, Mg, K) and exchangeable cation concentration. The solution extracts and exchange phases of both soils, salt accumulation in the soil increased by increasing the salinity and acidity of the water applied. Exchangeable sodium was related directly to the SAR of the applied solutions. The soil responded differently to the salty water and acid water. Both soil treatments released Ca, Mg and K to the soil solution from the dissolution of the primary minerals and cation exchange reaction.

Soil acidity is a major land degradation problem that limits crop production globally. The high cost of traditional liming materials (calcitic limestone, dolomite etc.) and the vast areas of land that require liming have led to the exploratory utilisation of alkaline industrial by- products such as fly ash and stainless steel slag. The liming potential and effects of liming with fly ash (from the Duvha power station) and processed stainless steel slag (Calmasil) on two acid soils were investigated in this study. The quality of fly ash and Calmasil as liming materials and their potential impacts on the soil quality and plant growth were investigated. The effects of liming with these materials on soil pH, EC, extractable Al, Mn, base cations and trace elements were investigated in an incubation experiment. A glasshouse trial was conducted to assess the effects of these materials on the growth of an acid intolerant crop, perennial rye grass. The incubation and glasshouse study were of a factorial design with two acid soils (the Avalon and Inanda soils), three materials (fly ash, Calmasil and lime); and five application rates of 0, 50, 100, 200 and 400% of the recommended optimum liming rate (OLR) for the growth of perennial rye grass. Characterization of fly ash showed that the major elements (>5%) present (Si > Al > Fe) are not comparable to lime (Ca > Si > Mg) and that it has a low liming potential (calcium carbonate equivalence (CCE) of 9.6%) in comparison to lime. The chemical composition of Calmasil is comparable to lime with Ca > Si > Mg as the major elements and it has a very high liming potential (CCE = 97%). The incubation experiment showed that adding fly ash and Calmasil increased the pH of both soils. However, at the optimum liming rate (100% OLR), only the treatment with Calmasil in the Avalon soil attained pH levels within the desired pH range. Extractable Al and Mn decreased with addition of fly ash and Calmasil to levels comparable to lime in the incubated soils. Addition of fly ash and Calmasil also increased the extractable base cations of both soils. The yield-response of perennial rye grass to treatments in both soils was in the following order: fly ash > Calmasil > lime. Application of fly ash at > 200% OLR in the Avalon soil caused injury of ryegrass. Application of fly ash and Calmasil at lower rates has great agronomic potential in ameliorating soil acidity. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Made available in DSpace on 2014-06-11T19:22:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-22Bitstream added on 2014-06-13T20:28:26Z : No. of bitstreams: 1 costa_chmc_me_botfca.pdf: 444896 bytes, checksum: 79a884c18686d0a77b3357b8cbc1bcfb (MD5) Bitstreams deleted on 2015-08-07T12:19:54Z: costa_chmc_me_botfca.pdf,. Added 1 bitstream(s) on 2015-08-07T12:20:56Z : No. of bitstreams: 1 000678831.pdf: 1444305 bytes, checksum: d3e614871d6cd55de66eda01f9f2bdd0 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / No sistema plantio direto praticamente não há revolvimento do solo e o consequente acúmulo de fertilizantes na superfície acelera o processo de acidificação, contínuo e acentuado que ocorre naturalmente em solos de regiões úmidas, onde, geralmente, é observada baixa disponibilidade de nutrientes e elevados teores de alumínio. Assim, da mesma forma que no sistema de cultivo convencional, no sistema plantio direto também existe a necessidade de aplicação de insumos em superfície, especialmente, materiais corretivos de acidez. Dentro deste enfoque, o trabalho foi desenvolvido na Fazenda Experimental Lageado, pertencente à Faculdade de Ciências Agronômicas – UNESP, Campus de Botucatu (SP), dando continuidade a um projeto de pesquisa que vem sendo conduzido desde 2002, com o objetivo de avaliar o efeito residual da aplicação superficial de corretivos na correção da acidez do solo, bem como na nutrição, na produtividade das culturas da soja e do sorgo e na produção de matéria seca e acúmulo de nutrientes da aveia-preta em região de inverno seco. O delineamento experimental utilizado foi em blocos casualizados em parcelas subdivididas, com 4 repetições. As parcelas foram constituídas por quatro doses de calcário (0, 1000, 2000 e 4000 kg ha-1) e as subparcelas por duas doses de gesso agrícola (0 e 2100 kg ha-1), aplicado em novembro 2004. Como cultura de verão foi utilizada a cultura da soja e na entressafra as culturas da aveia-preta e sorgo granífero. A aplicação de calcário em superfície promoveu diminuição da acidez e elevação nos teores de fósforo, cálcio, magnésio e matéria orgânica, em praticamente todo perfil do solo. A aplicação de gesso agrícola promoveu aumentos nos 2 teores de Ca trocável e S-SO42-, e diminuição no teor de Al trocável no solo... / In no tillage system the absence of soil mobilization consequently decreases places fertilizers on surface, affecting the acidification process. Like in conventional system, in no tillage it is also necessary input application, especially materials for acidity correction. The experiment was carried out in an experimental area, in the city of Botucatu (SP, Brazil), continuing a research project that has been conducted since 2002, to evaluate the long-term effects of surface application of lime and gypsum on acidity correction, nutrition, yield of soybean and sorghum, and dry matter production and nutrients accumulation on black oat in a dry winter region. The experimental design was the completely randomized with subdivided plots and four replications. The mains plots consisted of four dolomite limestone levels (0, 1000, 2000 e 4000 kg ha-1) and the subplots consisted areas with and without gypsum (0 and 2100 kg ha-1), applied in November 2004. Soybean was the summer crops and the off-season crops are black oat and grain sorghum Lime surface application reduced soil acidity and increased phosphorus, calcium, magnesium and organic matter, practically all the soil profile. Phosphogypsum application promoted increasing exchangeable Ca and S-SO42- contents, and decreased exchangeable Al in the soil, favoring the effects of surface liming on soil properties, mainly the surface layer (0-0.20 m). Base saturation values obtained at a depth of 0-0.20 m with liming were lower than those estimated by BS method, even with phosphogypsum application. Liming increased, on soybeans, foliar contents of N, P, Ca, Mg and S in 2008/09, and N, Ca and Mg, in 2009/10. In the presence of phosphogypsum increased the levels of N In no tillage system the absence of soil mobilization consequently... (Complete abstract click electronic access below)

The effects of surface applications of poultry manure on pH, exchangeable AI, exchangeable Al saturation and levels of available macronutrients in the surface and subsurface layers were investigated in some acid soils from the KwaZulu-Natal Midlands. Three field sites with a history of long-term applications of poultry manure were compared with adjacent fields where no manure had been applied. Results generally showed an increase in pHwater, pHKCI, exchangeable Ca, Mg, and K and extractable P and a decrease in exchangeable Al and exchangeable Al saturation in the surface soil to the depth to which the manure had been incorporated. Results also provided evidence for substantial downward movement of Ca and Mg into the subsoil layers (i.e. 30-60 cm) and their accumulation in exchangeable forms. There was a concomitant general increase in pHKcl and pHwater and decrease in exchangeable Al and exchangeable AI saturation in the subsoil layers. These results demonstrate that, under field conditions, surface applications of poultry manure can cause the amelioration of subsoil acidity. This is an extremely important finding since subsoil acidity is characteristically extremely difficult and costly to ameliorate. A leaching column study was subsequently conducted to investigate the mechanisms by which surface applications of poultry manure ameliorate both top- and subsoil acidity. The soil used, originating from one of the field sites, had not previously been treated with poultry manure and had a subsoil pHKCI of 4.25 and an exchangeable acidity concentration of 1.79 cmolJkg. Three forms of poultry manure (layer, broiler and free range) were incorporated into the surface 5 cm of soil columns at rates equivalent to 5, 10 and 30 Mg/ha. Columns were maintained in glasshouse conditions for a period of 108 days and over that period they were leached on four separate occasions (receiving a total of 825 mm of simulated rainfall). At the conclusion of the experiment, the soil columns were cut into sections for chemical analysis. Applications of poultry manure to the surface soil markedly increased pHwater, pHKcl, exchangeable Ca, Mg, K and Na concentrations and decreased exchangeable Al levels in the surface 5 cm layer. They also increased the concentrations of soluble C, soluble salts, total Al and organically-complexed Al in soil solution. These effects were most pronounced with layer manure and greater at the higher rate of application. The manure-induced decrease in exchangeable AI, but increase in total AI, in soil solution was attributed to soluble salts, originating from the manure, displacing exchangeable Al into solution where it was subsequently complexed by soluble organic matter. Analysis of subsoil layers (5-15, 15-25, 25-35 and 35-45 cm) at the conclusion of the experiment showed that surface applications of poultry manure decreased concentrations of exchangeable Al in the subsoil but had no effect on pHKCl and depressed values for pHwater. It was suggested that manure-derived urea leached into the subsoil and was then hydrolysed causing an increase in pH and precipitation of exchangeable Al as insoluble hydroxy-AI oxides. Towards the conclusion of the experiment nitrification began to proceed, causing subsoil pHKCl values to decrease back to their original values. Analysis of the inorganic-N content of leachates and soil layers provided circumstantial evidence for this mechanism. High concentrations of soluble salts in the subsoil layers (caused by leaching from the manure) resulted in displacement of exchangeable A13+ and W into soil solution so that the electrical conductivity and concentrations of total and monomeric Al were elevated and pHwater was depressed in the subsoil (15-45 cm) of poultry manure-treated columns. It was concluded that the results underline the opposing effects that poultry manure applications have on (i) raising soil pH and lowering exchangeable Al but at the same time (ii) greatly increasing soluble salt concentrations and thus displacing At3+ and H+ back into soil solution. They also have suggested the importance of the release of N during manure decomposition in influencing soil pH (through the processes of ammonification, urea hydrolysis and nitrification) and therefore other soil chemical properties. It is, however, clear that the long-term effect of surface applications of poultry manure is generally to ameliorate subsoil acidity by raising subsoil pH and lowering exchangeable Al concentrations. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

Magistro darbe tiriamas skirtingų kalkinių medžiagų poveikis dirvožemio potencialiajam rūgštingumui ir judriajam aliuminiui. Darbo objektas – keturios kalkinės medžiagos: malta kreida, „Agrokalkės” (klinčių ir nedegtų kalkių miltelių mišinys), dolomitmičiai (dolomito atsijos), ir granuliuota kalkinė medžiaga „Kalktrąšė”. Darbo metodai – kalkinėmis medžiagomis buvo pakalkintos dvi, pasotinto balkšvažemio Dystric Albeluvisol ir nepasotinto balkšvažemio Eutric Albeluvisol, lauko bandymų aikštelės; dirvožemio potencialusis rūgštingumas nustatytas laboratorijoje elektroniniu pH-metru, judriojo aliuminio kiekis Sokolovo metodu; gauti duomenys palyginti tarpusavyje matematiniais-statistiniais metodais. Darbo rezultatai. Atlikus tyrimus nustatyta, kad efektyviausiai, bei statistiškai patikimai (p<0,05) dirvožemio rūgštingumą sumažino dulkios kalkinės medžiagos – kreida ir „Agrokalkės”. Stambesnės frakcijos, trupintos kalkinės medžiagos – dolomitmičių statistiškai patikimas poveikis nustatytas tik antrojoje bandymų aikštelėje nepasotintame balkšvažemyje Eutric Albeluvisol praėjus aštuoniolikai mėnesių po kalkinimo. Granuliuota kalkinė medžiaga „Kalktrąšė“ statistiškai nepatikimai veikė dirvožemio rūgštingumą. Efektyviausiai (99%) statistiškai patikimai (p<0,05), judriojo Al kiekį sumažino „Agrokalkės“. Taip pat efektyviai, kreida 97% ir dolomitmilčiai 79%, statistiškai patikimai (p<0,05) sumažino judriojo Al kiekį dirvožemyje. „Kalktrąšė“ iš visų tirtų kalkinių medžiagų prasčiausiai... [toliau žr. visą tekstą] / The Master Thesis analyses the impact of different liming materials on potential soil acidity and mobile aluminium. Object – four liming materials: powder chalk, agrolime (mixture of limestone and uncalcined lime powder), dolomite powder (dolomite siftings), and pelletized lime fertilizer “Kalktrąšė”. Methods – two experimental field plots, Dystric Albeluvisol and Eutric Albeluvisol, had been limed using four different liming materials; potential soil acidity had been determined in the laboratory by the electronic pH-metre, the amount of mobile aluminium was estimated by Sokolov method; the obtained data were inter-compared by the mathematical-statistical methods. Results. The research demonstrated that the use of powdered lime materials, i.e. chalk and agrolime, resulted in the most effective and statistically reliable (p<0.05) reduction of soil acidity. A statistically reliable impact of dolomite powder, a crushed lime material of larger fractions, was recorded only in the second testing ground, Eutric Albeluvisol, eighteen months after liming. Moreover, the effect of pelletized lime fertilizer “Kalktrąšė” on soil acidity was not statistically reliable. In contrast, agrolime was the most effective (99%) and statistically reliable (p<0.05) in reducing the amount of mobile aluminium. A similar, statistically reliable (p<0.05) impact was caused by chalk 97% and dolomite 79% powder (p<0.05), what reduce mobile Al in soil. Among all liming materials “Kalktrąšė” resulted in the... [to full text]

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