Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In Brazil, the SMP buffer has been used since the 60's as the main method to estimate the potential acidity and/or the soil lime requirement. However, SMP contains pnitrophenol and potassium chromate, substances with high potential for environmental contamination and able to promote the development of methemoglobin and carcinomas in lab handlers as a result of continued exposure. This work aimed to develop a buffer solution free of hazardous substances which can mimic the acid-base characteristics of the SMP buffer, with the composition used in the states of RS and SC (SMP-RS/SC), in response to the acidity of Brazilian soils. To develop the new buffer, imidazole and 2-(Nmorpholino) ethanessulfonic acid monohydrate (MES) were used as substitutes for pnitrophenol and potassium chromate, respectively. The titration of the buffer SMP-RS/SC with HCl was carried out and these data were used as the starting point for the new buffer reproduce the potentiometric behavior of SMP-RS/SC buffer. To achieve this, multiparametric regression analysis was used, taking as adjustable parameters the pKa values and the concentrations of the components of the new buffer. The final composition for the new buffer, called Santa Maria buffer (TSM) was obtained with: 37.5 mM of triethanolamine; 17.3 mM of imidazole; 30.7 mM of MES; 20.7 mM of calcium acetate and 721 mM of calcium chloride; with initial pH adjusted to 7.5. For comparison between TSM and SMP-RS/SC, we utilized 42 soil samples collected in different physiographic regions of Brazil. Linear regression was performed with pH-SMP and pHTSM values, and also, between the lime requirement by SMP and TSM, reaching determination coefficient (R2) greater than 0.99 in both cases. The TSM had equivalent sensitivity to the SMP-RS/SC in differentiating the acidity degree of soils, and can be used replacing this, without the need for change in routine laboratory and interpretations already developed to estimate the potential acidity or need limestone of soil. At temperature from 22 to 27 °C, the TSM has a long shelf life and can be stored in plasticpolypropylene or glass containers protected from light, for a period of 120 to 150 days. The replacement of SMP-RS/SC buffer by TSM is a viable alternative for soil testing laboratories to avoid the generation of hazardous wastes and to reducing the health risks for the lab handlers. / No Brasil, o tampão SMP vem sendo utilizado desde a década de 60 como o principal método para a estimativa da acidez potencial e/ou da necessidade de calcário do solo. No entanto, em sua composição, a solução SMP apresenta p-nitrofenol e cromato de potássio, substâncias essas com elevado potencial de contaminação ambiental e capazes de promover o desenvolvimento de metahemoglobina e carcinomas aos seus manipuladores, como conseqüência da exposição continuada. Este trabalho teve como objetivo principal desenvolver uma solução tampão livre de substâncias tóxicas, capaz de mimetizar as características ácido-base do tampão SMP, na composição utilizada nos estados do RS e SC (SMP-RS/SC), em resposta à acidez de solos brasileiros. Para o desenvolvimento do novo tampão, utilizaram-se como substitutos ao p-nitrofenol e ao cromato de potássio, o imidazol e o ácido 2-(N-morfolino) etanossulfônico monohidratado (MES), respectivamente. Realizou-se a titulação do tampão SMP-RS/SC com HCl e esses dados de titulação foram utilizados como ponto de partida para que o novo tampão reproduzisse o comportamento potenciométrico do tampão SMP-RS/SC. Para tanto, empregou-se análise de regressão multiparamétrica, considerando como variáveis os valores de pKa e as concentrações dos componentes do novo tampão. A composição final para o novo tampão, denominado Tampão Santa Maria (TSM), foi obtida com: 37,5 mM de trietanolamina; 17,3 mM de imidazol; 30,7 mM de MES; 20,7 mM de acetato de cálcio e 721 mM de cloreto de cálcio; com pH inicial ajustado a 7,5. Para comparação entre o TSM e o SMP-RS/SC, utilizaram-se 42 amostras de solo oriundas de diferentes regiões fisiográficas do Brasil. Ajustou-se regressão linear entre os valores de pH-TSM e pH-SMP, e também, entre a recomendação de calcário por TSM e por SMP, alcançando-se coeficiente de determinação (R2) superior a 0,99 em ambos os casos. O TSM apresentou sensibilidade equivalente ao SMP-RS/SC na diferenciação do grau de acidez dos solos estudados, podendo ser utilizado em substituição a esse, sem a necessidade de alteração da rotina e das interpretações laboratoriais já desenvolvidas para a estimativa da acidez potencial ou necessidade de calcário do solo. À temperatura de 22 a 27 ºC, o TSM apresenta uma longa vida útil, podendo ser armazenado em recipiente de plástico-polipropileno ou vidro protegido da luz, por um período de 120 a 150 dias. A substituição do tampão SMP-RS/SC pelo TSM é uma alternativa viável para os laboratórios de análise de solo evitarem a geração de resíduos perigosos e reduzirem os riscos à saúde dos técnicos manipuladores.

The bulk of Zimbabwe’s groundnut (Arachis hypogaea L.) crop is grown on sandy soils in the smallholder sector where sustainable production is hindered by acid soil infertility. The study goal was thus to examine the effects of soil acidity amelioration by four Ca-containing materials on nutrient composition, vegetative and reproductive growth, and quality of groundnut to formulate ameliorative strategies to improve productivity on acid soils. The effectiveness of calcitic lime (CL), dolomitic lime (DL), gypsum (G) and single superphosphate (SSP) in ameliorating soil acidity was determined in field experiments conducted for three seasons at two Research Stations in Zimbabwe, and in greenhouse experiments conducted for two seasons at Harare Research Station. In both experiments the lime application rates were from 0 to 4000 kg ha-1, while G application rates were from 0 to 3450 kg ha-1, and those of SSP were from 0 to 250 kg ha-1. Calcitic or dolomitic lime applied at 2000 or 4000 kg ha-1 increased soil pH and Ca and Mg contents in the pod and root zones, and in the plant material. Gypsum and SSP applications at 200 and 250 kg ha-1 respectively, had no significant effects on pH, Ca and Mg levels, but when applied in equivalent amounts of Ca as lime, gypsum improved soil Ca status. Effects of the four ameliorants on the N, P and K levels in the soils and in plant material were generally neither significant nor consistent. The direct and residual benefits of application of CL or DL were manifested in improved plant stands, better growth, nodulation, productivity and quality of groundnut. Gypsum applied at equal Ca rates as CL or DL was the superior Ca-source in improving pod and kernel quality. By the end of the third season, the increases in cumulative kernel yields due to application of 4000 kg ha-1 lime over non-application were up to 319%. The major growth-limiting factors on the studied acid soils were identified as deficiencies of Ca and Mg, and low pH per se. In a field experiment conducted to evaluate the tolerance of 15 groundnut genotypes to soil acidity, significant differences in yield and nutrient utilization efficiency of the genotypes were observed, implying that productivity on acid soils can be increased by growing genotypes efficient in uptake and utilization of nutrients. Results from greenhouse and growth chamber studies conducted to examine the effects of pH (3.0 - 7.0) and its interactions with Ca (0 - 2000 µM Ca) on early seedling growth and reproductive growth of groundnut indicated that low pH per se has a major detrimental impact on seedling survival, growth, pod formation, yield and quality of groundnut, but not on germination. The adverse effects of low pH were more pronounced in the absence of Ca, and became progressively less as the solution Ca concentrations increased. Further experiments showed that it is feasible to mitigate the adverse effects of soil acidity on groundnut germination and seedling survival by pelleting seeds with small amounts of CaCO3, or priming with CaSO4. / Dissertation (PhD (Plant Production: Agronomy))--University of Pretoria, 2003. / Plant Production and Soil Science / unrestricted

Breeding maize (Zea mays L.) for tolerance to acidic soils could improve maize yields. The current study aims to identify maize genotypes with tolerance to acidic soils, as well as identifying secondary traits associated with the tolerance to soil acidity. Ten maize varieties were screened for tolerance to aluminium (Al) toxicity under glasshouse, laboratory and field conditions. In the glasshouse, two soil acidity levels (limed and unlimed soil) were used and the experiment was set up in a complete randomised design (CRD) with three replications. The experiment lasted for 10 days and measurements were taken on plant height (PH), leaf area, stem diameter and dry matter. In the laboratory, a haematoxylin staining (HS) experiment was conducted to determine the response of 10 maize varieties to Al toxicity. Two Al concentrations (0 and 222 μM) were used and the experiment was set up in a completely randomized design with three replications. After 7 days, shoot length, was recorded. Five stress tolerance indices were estimated to determine the resilience of each genotype. A root growth stress tolerance index was also computed for both experimental procedures. In the field, two trials were established at two sites, namely Mbinja and Mpumaze. Limed and unlimed plots were used, and the trial was set up in a randomized complete block design with three replications. Maize kernel yield and other standard field parameters were recorded. Selection of tolerant genotypes from the field screening was also done using three indices, namely harmonic mean (HM), stress tolerance index (STI) and stress susceptibility index (SSI). Both the glasshouse and laboratory assays identified similar genotypes of maize as being tolerant. These tolerant genotypes were Ngoyi, PANBG3492 BT, PAN 6Q408 and PHB 3442 based on the root growth stress tolerance index (RGSTI). It was therefore demonstrated that these two assays produced the same level of efficiency in identifying tolerant genotypes using this index. Based on ranking of seedling vigour index under soil acidity stress, the top three genotypes at Mpumaze were PHB32W71, PAN6616 and Sahara while at Mbinja, the top three were PAN6616, PAN6Q408 CB and PAN6P110. The genotypes PANBG3492 BT, PAN6Q408 and PHB3442 were also found to be tolerant to acidic soils at seedling stage. These genotypes are recommended for further evaluation in more sites to confirm their tolerance and yield potential under acidic soils. The study also revealed that plant height, leaf area and stem diameter could be used for indirect selection for tolerance to Al toxicity under glasshouse conditions. The seedling vigour index was also effective in identifying tolerant genotypes under glasshouse conditions. On the other hand, shoot length stress tolerance index and the haematoxylin score were useful for indirect selection for tolerance to Al toxicity in the laboratory. In the field, it was observed that ear length, leaf area and ear diameter can be useful in identifying genotypes that are tolerant to soil acidity. They can therefore be useful as indirect selection criteria under field conditions. Additionally, the best selection indices for identifying soil acidity tolerant genotypes under field conditions were the HM and the STI. It is recommended that varieties that were identified as tolerant be further evaluated in several soil acidity hot spots to confirm their tolerance and stability of performance under field conditions. / Agriculture and  Animal Health / M. Sc. (Agriculture)

Zur Untersuchung des Einflusses der Bodenschutzkalkung gegen die flächendeckende Bodenversauerung im sächsischen Mittelgebirge wurde die Regenwurmfauna an acht Punkten der Bodenzustanderhebung (BZE-Punkte) im Erzgebirge und im Vogtland erfasst. Die Untersuchungspunkte sind durch Fichtenforste auf vier verschiedenen Lokalbodenformen charakterisiert, jeweils nicht gekalkt und gekalkt. Die verwendeten chemischen Daten stammen aus der Bodenzustandserhebung. Die Erfassung der Lumbriciden erfolgte mittels Elektroaustreibung und anschließender Handauslese, die Tiere wurden lebend und mit Darminhalt gewogen. Daraus wurden die Populationsparameter Individuendichte und Biomasse pro Quadratmeter ermittelt und mit dem U-Test nach Wilcoxon, Mann und Whitney auf signifikante Unterschiede geprüft. Bei Betrachtung der Daten der BZE fallen auf den gekalkten Flächen im Vergleich zu den nicht gekalkten Flächen der angehobene pH-Wert, die gesteigerte effektive Austauschkapazität (AKe) und die erhöhte Basensättigung (BS) im organischen Auflagehorizont sowohl in der Streu und in der fermentierten organischen Auflage (L + Of) als auch in der humifizierten organischen Auflage (Oh) auf. [...] Das C/N-Verhältnis weist in keinem der Horizonte einen offensichtlichen Zusammenhang zur Kalkung auf. Auf den gekalkten Flächen wurde sowohl eine höhere Individuendichte als auch eine höhere Biomasse der Lumbriciden festgestellt. Die Unterschiede sind zu verschiedenen Niveaus signifikant. Zwischen den Populationparametern und pH-Wert, AKe und Basensättigung besteht kein linearer Zusammenhang, bei erhöhten Werten dieser Bodenchemie-Komponenten wurden jedoch höhere Individuendichten und Biomassen festgestellt. Zum C/N-Verhältnis konnte keine Beziehung festgestellt werden. Auf den gekalkten Flächen wurden auch mehr Arten als auf den nicht gekalkten gezählt. [...] Es ist zu überlegen, inwieweit sich (Wieder-)Ansiedelungsmaßnahmen entsprechender Arten durchführen ließen.:1 Einleitung und Zielstellung ...........................................................................6 2 Grundlagen und Methodik ...........................................................................9 2.1 Naturraum ................................................................................................9 2.2 Regenwurmbiologie ................................................................................13 2.3 Methodik .................................................................................................18 2.4 Statistik ...................................................................................................21 3 Ergebnisse .................................................................................................23 3.1 Chemische Daten der Bodenzustandserhebung ....................................23 3.2 Individuendichte und Biomasse ..............................................................28 3.3 Zusammenhänge zur Bodenchemie .......................................................32 3.4 Artenfunde .............................................................................................42 4 Diskussion ..................................................................................................43 4.1 Kritik an der Methodik und der statistischen Auswertung .......................43 4.2 Ergebnisbewertung ................................................................................45 5 Zusammenfassung und Fazit ......................................................................49 6 Abstract .......................................................................................................51 7 Literaturverzeichnis .....................................................................................52 Anhang ...........................................................................................................62 / Since the end of the last century, liming is a common melioration measure in German forest and wood management against the acidity of soils, especially in the uplands like the Ore Mountains (Erzgebirge) in Saxony. To record changes in ecosystems, there are different monitoring programms, for example the 'Bodenzustandserhebung (BZE)'. But also a biological component for detecting effects of liming on flora and fauna is needed. Earthworms are a very important group of the soil fauna. Therefore, this study was aimed at this family to track their reaction to liming in spruce forests in the Saxon Ore Mountains. The expectation of a positive reaction could be significantly approved on the basis of four paired habitats, each couple with a not limed and a limed counter-part. Four species of earthworms were recorded. Three of them are epigeic forms, one is an endogeic type. Important factors for their abundance and biomass are pH, exchange capacity of cations and saturation of bases. A linear correlation was not detected. In this study, the ratio of carbon and nitrogen in soils showed a link neither to lime nor to earthworms abundance or biomass. As a result, liming is a reasonable measure to reactivate the biological components in acid affected soils, but it is also needed to cultivate a more various forest ecosystem.:1 Einleitung und Zielstellung ...........................................................................6 2 Grundlagen und Methodik ...........................................................................9 2.1 Naturraum ................................................................................................9 2.2 Regenwurmbiologie ................................................................................13 2.3 Methodik .................................................................................................18 2.4 Statistik ...................................................................................................21 3 Ergebnisse .................................................................................................23 3.1 Chemische Daten der Bodenzustandserhebung ....................................23 3.2 Individuendichte und Biomasse ..............................................................28 3.3 Zusammenhänge zur Bodenchemie .......................................................32 3.4 Artenfunde .............................................................................................42 4 Diskussion ..................................................................................................43 4.1 Kritik an der Methodik und der statistischen Auswertung .......................43 4.2 Ergebnisbewertung ................................................................................45 5 Zusammenfassung und Fazit ......................................................................49 6 Abstract .......................................................................................................51 7 Literaturverzeichnis .....................................................................................52 Anhang ...........................................................................................................62

This thesis compares the in situ water balance of common annual production systems (wheat, lupin, subclover and serradella) with a grazed perennial system (lucerne) at a site in the Avon Catchment, Western Australia. Using a physically-based water balance approach the value of a plant based solution in redressing the hydrological imbalance that has become a feature of much of the dryland agricultural region of Western Australia is investigated. The effectiveness of lucerne in providing greater available storage for buffering large rainfall events, as compared to the annual systems, is illustrated. Continued transpiration following out-of-season rainfall events maintains a larger available storage capacity. In contrast, the annual systems that are fallow over summer only withdrew a small fraction of water by soil evaporation between rainfall events. Under annual systems, the profile moisture store was sequentially increased to the extent that additional increments of rainfall could potentially contribute to deep drainage. A particular focus of this study has been to investigate the presence of soil constraints to root growth, and to assess how these constraints affect the water balance. A site survey indicated the soil penetration resistance was sufficient to impose a physical constraint to root growth. Published literature on the site shows soil acidity is also at a level imposing chemical constraints to root growth. A root growth model “Rootmodel”, for predicting root growth with and without soil constraints is examined in detail as a method for providing root growth parameters for inclusion into the numerical water balance model, SWIM based on Richard’s equation. Functions developed from “Rootmodel” adequately describe the effect of profile limitations to root growth, such as soil strength, moisture availability and temperature. Recommendations are made for inclusion of a growth suppressing function in “rootmodel” based on the chemical limitation of low pH. The effects of soil acidity on the root growth of several species is investigated experimentally and the resultant root data provided a reference point by which the simplified prediction of root growth built into SWIM could be adjusted using a linear reduction function. A similar linear reduction function is also employed to impose a physical constraint in the form of high penetration resistance.

Made available in DSpace on 2017-07-25T19:29:58Z (GMT). No. of bitstreams: 1 Maik Rodrighero.pdf: 828244 bytes, checksum: b17d81b60eaad6eff20ad64666064e48 (MD5) Previous issue date: 2012-12-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / To control soil acidity in no-till systems, lime is broadcast on the surface without incorporation. In order to test the hypothesis that the source and particle size of the corrective influence the soil reaction and crop response to lime on the surface in no-till system, two experiments were conducted in Tibagi (PR), one in clayey Oxisol and another in sandy Litholic Neosol. A randomized complete block design was used in a factorial 2 × 2 × 4 with three replications, in each experiment. The treatments consisted of four rates of lime on the surface, estimated to raise the base saturation of the topsoil (0-20 cm), at 50, 70 and 90%; two sources of lime were used, calcitic and dolomitic,and two ranges of lime material effective calcium carbonate equivalent (ECCE), range B (ECCE 60-75%) and range D (ECCE > 90%). In both experiments, the lime was applied on the soil surface in August 2010. During the spring-summer season in 2010- 11 and 2011-12, corn and soybean were grown on the clayey soil, and soybean and corn on the sandy soil, respectively. After 12 months of liming, soil chemical analyses were performed in samples taken at the 0-5, 5-10, 10-20, 20-40, and 40-60 cm depths. Leaf samples of corn and soybean were taken during crop flowering, in the second year of cultivation, for foliar diagnosis. Grain yields of corn and soybean, in both experiments,were evaluated in two years, after the physiological maturity, and grain moisture was corrected to 130 g kg-1. Surface application of lime in both soils, after 12 months, promoted amelioration of soil acidity mainly in the 0-5 cm layer and, to a lesser extent in the 5-10 cm, regardless of the source and range of lime ECCE. Calcitic lime showed a stronger reaction than dolomitic lime in the soil surface layers. The extraction with cation exchange resin overestimated the exchangeable Ca and Mg content in relation to the 0.1 mol L-1 KCl solution when coarser grain size lime was applied on the surface. Surface liming increased the Ca-leaf content, especially with the use of calcitic lime, and Mg-leaf content mainly with the use of dolomitic limestone, and reduced Mn and Zn contents in the leaves, regardless of the source of lime, in the corn and soybean crops. Grain yields of corn and soybean in clayey Oxisol and corn in sandy Litholic Neosol were increased with the lime rates, but were not affected by sources and ECCE ranges of material lime. Surface application of lime in soils under no-till was proved of fundamental importance to maximize crop grain yield, regardless of the lime source being calcitic or dolomitic, or the ECCE range, B or D of the material lime. / No sistema plantio direto, a correção da acidez é feita por meio da aplicação de calcário na superfície sem incorporação. Com a hipótese de que a fonte e a granulometria dos corretivos interferem na reação do solo e na resposta das culturas à calagem superficial em plantio direto, foram realizados dois experimentos em Tibagi (PR), sendo um em Latossolo Vermelho argiloso e outro em Neossolo Litólico arenoso, no período de 2010 a 2012. O delineamento empregado, em cada experimento, foi o de blocos completos ao acaso, em esquema fatorial 2 × 2 × 4, com três repetições. Os tratamentos foram constituídos de quatro doses de calcário na superfície, estimadas para elevar a saturação por bases do solo (0–20 cm), a 50, 70 e 90%; duas fontes de calcário, calcítico e dolomítico; e duas faixas de poder relativo de neutralização total (PRNT), faixa B (PRNT de 60 a 75%) e faixa D (PRNT > 90%). Nos dois experimentos, o calcário foi aplicado a lanço sobre a superfície do solo em agosto de 2010. Realizaram-se dois cultivos em 2010–11 e 2011–12, com milho e soja no solo argiloso, e soja e milho no solo arenoso. Após 12 meses da aplicação, análises químicas de solo foram realizadas em amostras coletadas nas camadas de 0–5, 5–10, 10–20, 20–40 e 40–60 cm de profundidade. Amostras de folhas de milho e soja foram coletadas por ocasião do florescimento das culturas, no segundo ano de cultivo, para fins de diagnose foliar. A produtividade de grãos de milho e soja, nos dois experimentos, foi avaliada, nos dois anos, após a maturação fisiológica, corrigindo-se a umidade dos grãos para 130 g kg-1 de água. A aplicação superficial de calcário nos dois solos, após 12 meses, promoveu correção da acidez principalmente na camada de 0-5 cm e, em menor grau, na de 5-10 cm, independentemente da fonte e da faixa de PRNT dos corretivos. O calcário calcítico apresentou maior reação do que o calcário dolomítico nas camadas superficiais do solo. A extração com a resina de troca catiônica superestimou os teores de Ca e Mg trocáveis em relação à solução de KCl 1 mol L-1 quando houve aplicação superficial de calcário com granulometria mais grossa. A calagem superficial aumentou as concentrações de Ca-foliar, principalmente com a utilização de calcário calcítico, e de Mg-foliar,especialmente com o uso de calcário dolomítico, e reduziu os teores foliares de Mn e Zn, independentemente da fonte de calcário, nas culturas de milho e soja. As produtividades de milho e soja, no Latossolo argiloso, e de milho, no Neossolo arenoso,foram aumentadas com as doses de calcário, mas não foram influenciadas pelas fontes e faixas de PRNT dos corretivos. A calagem superficial em solos sob plantio direto se mostrou de fundamental importância para maximizar a produtividade de grãos das culturas, independentemente da fonte de calcário, calcítico ou dolomítico, e da faixa, B ou D, de PRNT dos corretivos.

Made available in DSpace on 2017-07-25T19:30:47Z (GMT). No. of bitstreams: 1 Adriano Haliski.pdf: 1087998 bytes, checksum: 06568ec8622f2204e3d6d86c65fa29a8 (MD5) Previous issue date: 2015-02-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nitrogen fertilization can increase the efficiency of surface liming on soil acidity correction and benefit crop production in long term no-till systems. Because the soil organic matter content under no-till is high, especially in the soil surface layers, the aluminum (Al) toxicity may be low, even in high acidity conditions. This study was carried out with the purpose of evaluate the soil chemical attributes, grain yield, and critical levels for the development of soybean after surface application of lime and ammoniacal nitrogen (N-NH4NO3) in crops of autumn-winter predecessors. The experiment was conducted in Ponta Grossa, Parana State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox (Oxisol) under long term continuous no-till (26 years). The experimental design used was a randomized block, in a split plot arrangement, with three replications. In the plots, were applied, in May 2004, four rates of lime on the soil surface (0, 4, 8, and 12 t ha-1) and, in the subplots, were applied annually, since 2004, four rates of N-NH4NO3 (0, 60, 120 and 180 kg ha-1) in top dressing in the black oat or wheat crops. In crop rotation was used corn, soybeans or beans in the spring-summer season and black oat or wheat in the autumn-winter season. Soybean was sown in November 2007 (cv. CD 214 RR), 2009 (cv. CD 206 RR), 2010 (cv. BMX Apolo RR), 2012 (cv. NA 5909 RG), and 2013 (cv. BMX Ativa RR). Soil samples were collected annually before soybean sowing at the 0–0.05, 0.05–0.10, and 0.10–0.20 m depths. Surface liming increased pH and the contents of exchangeable Ca2+ and Mg2+, and reduced the content of exchangeable Al3+ to a depth of 0.20 m. Nitrogen fertilization reduced pH and the contents of exchangeable Ca2+ and Mg2+, especially to a depth of 0.10 m, and increased the content of exchangeable Al3+ to a depth of 0.20 m. Surface application of lime increased the soybean grain yields for all N-NH4NO3 rates used in black oat or wheat crops. In unlimed plots, acidification caused by nitrogen fertilization severely limited the soybean grain yield. The critical levels of pH in CaCl2, base saturation, exchangeable Al3+, and Al3+ saturation in the 0–0.20 m layer for soybean production were 4.9, 33%, 8.0 mmolc dm-3, and 30%, respectively. Surface application of lime proved to be a key practice to ensure high soybean yields when high ammoniacal fertilizer rates are applied frequently in no-till systems. / A adubação nitrogenada pode aumentar a eficiência da calagem superficial na correção da acidez do solo e beneficiar a produção das culturas em longo prazo no sistema plantio direto. Como no sistema plantio direto os teores de matéria orgânica são elevados, especialmente nas camadas superficiais do solo, a toxicidade de alumínio (Al) pode ser baixa, mesmo em condições de alta acidez. Este trabalho foi realizado com o objetivo de avaliar as alterações químicas do solo, a produtividade, e os níveis críticos para o desenvolvimento da cultura da soja após aplicação superficial de calcário e de nitrogênio amoniacal (N–NH4NO3) nas culturas antecessoras de outono–inverno. O experimento foi realizado em Ponta Grossa (PR), em um Latossolo Vermelho distrófico textura média manejado há 26 anos sob plantio direto no momento da instalação. O delineamento experimental foi o de blocos ao acaso, em parcelas subdivididas, com três repetições. Nas parcelas, foram aplicadas, em maio de 2004, quatro doses de calcário dolomítico na superfície (0, 4, 8 e 12 t ha-1) e, nas subparcelas, foram aplicadas, anualmente, desde 2004, quatro doses de N–NH4NO3 (0, 60, 120 e 180 kg ha-1) em cobertura nas culturas de aveia preta ou trigo. Na rotação de culturas foram utilizados milho, soja ou feijão na estação de primavera–verão e aveia preta ou trigo na estação de outono–inverno. A soja foi cultivada em novembro de 2007 (cv. CD 214 RR), 2009 (cv. CD 206 RR), 2010 (cv. BMX Apolo RR), 2012 (cv. NA 5909 RG) e 2013 (cv. BMX Ativa RR). Amostras de solo foram coletadas anualmente, antes da semeadura de soja, nas camadas de 0–0,05, 0,05–0,10 e 0,10– 0,20 m. A aplicação superficial de calcário elevou o pH e os teores de Ca2+ e Mg2+ trocáveis, e reduziu o teor de Al3+ trocável até a profundidade de 0,20 m. A adubação nitrogenada diminuiu o pH e os teores de Ca2+ e Mg2+ trocáveis, principalmente até a profundidade de 0,10 m, e elevou o teor de Al3+ trocável até a profundidade de 0,20 m. A aplicação superficial de calcário aumentou a produtividade de grãos de soja para todas as doses de N–NH4NO3 empregadas nas culturas de aveia preta ou trigo. Nas parcelas sem calagem, a acidificação provocada pela adubação nitrogenada limitou severamente a produtividade de grãos de soja. Os níveis críticos de pH em CaCl2, saturação por bases, Al3+ trocável e saturação por Al 3+, na camada de 0–0,20 m, para a produção de soja foram 4,9, 33%, 8,0 mmolc dm-3 e 30%, respectivamente. A calagem na superfície mostrou ser uma prática fundamental para garantir altos tetos de produtividade de soja quando altas doses de nitrogênio amoniacal são aplicadas com frequência no sistema plantio direto.

Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2018-06-13T14:19:35Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Andre Carlos Auler.pdf: 3700376 bytes, checksum: c1ec033a97820b9055b6c86fad79d308 (MD5) / Made available in DSpace on 2018-06-13T14:19:35Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Andre Carlos Auler.pdf: 3700376 bytes, checksum: c1ec033a97820b9055b6c86fad79d308 (MD5) Previous issue date: 2018-04-25 / A acidez do solo é um importante fator que restringe a produção agrícola no mundo. Solos ácidos apresentam baixos valores de pH, elevados teores de alumínio trocável (Al3+) e baixa disponibilidade de cálcio (Ca2+), magnésio (Mg2+) e potássio (K+) trocáveis. Para corrigir os problemas causados pela acidez do solo, diversos materiais podem ser utilizados, com destaque para os carbonatos e os silicatos de Ca e Mg. Tais produtos apresentam distinções quanto a sua composição química e características físicas, o que repercute sobre sua reatividade no solo. Contudo, com o advento do plantio direto (SPD), os corretivos da acidez são aplicados sobre a superfície do solo, o que restringe a correção da acidez em subsuperfície. Neste contexto, o gesso agrícola é aplicado em associação aos corretivos da acidez. Embora o gesso agrícola não atue sobre a acidez ativa do solo, em subsuperfície ele atua reduzindo os teores de Al3+ e elevando os teores de Ca2+, o que melhora o ambiente radicular. O manejo químico do solo, por meio da aplicação de corretivos da acidez e de gesso agrícola pode alterar a estrutura do solo e os processos termodinâmicos que nela ocorrem. Neste contexto, o objetivo geral deste estudo foi avaliar os efeitos de corretivos de acidez do solo [calcário de rocha moída (CRM), escória de siderurgia (ES) e calcário calcinado (CC)], associados ou não ao gesso agrícola, sobre os atributos físicos e químicos do solo e a produtividade de culturas no SPD. Para isso, instalou-se um experimento em um LATOSSOLO VERMELHO-AMARELO Distrófico de textura argilo-arenosa, em Ponta Grossa-PR. Os tratamentos foram os três corretivos da acidez do solo CRM (3,8 Mg ha-1), ES (4,2 Mg ha-1) e CC (2,7 Mg ha-1) mais um tratamento controle (sem correção da acidez), associados ou não ao gesso agrícola (2,4 Mg ha-1). As doses dos corretivos foram calculadas para elevar a saturação por bases da camada 0-0,20 m a 70 %, com base em seus equivalentes carbonatos. A dose de gesso agrícola foi calculada com base no teor de argila do solo. Os corretivos e o gesso agrícola foram aplicados sobre a superfície do solo, em agosto de 2015. A rotação de culturas utilizada foi milho (2015/16) – trigo (2016) – soja (2016/17) - aveia preta (2017) – feijão (2017/18). Após a colheita do milho e do trigo, respectivamente aos 7 e aos 15 meses após a aplicação dos tratamentos, foram coletadas amostras indeformadas e deformadas de solo. Foram coletadas amostras indeformadas de solo em (i) monólitos, nas camadas 0-0,05; 0,05-0,10 e 0,10-0,20 m, para avaliação da agregação e da estabilidade de agregados; e em (ii) anéis volumétricos, nas camadas 0-0,05; 0,05-0,10; 0,10-0,20; 0,20-0,40 e 0,40-0,60 m, para avaliação da densidade do solo (Ds), porosidade total (Pt), macroporosidade (Ma), microporosidade (Mi) e retenção de água no solo. As amostras deformadas foram coletadas nas mesmas camadas de coleta dos anéis volumétricos, para determinação dos componentes da acidez do solo (pH, H+Al e Al3+), cátions básicos trocáveis (Ca2+, Mg2+ e K+) e teores de carbono lábil (COXP) e total (CO). A produtividade das culturas foi avaliada e utilizada para se determinar a eficiência agronômica dos corretivos e do gesso agrícola. Tanto aos 7 quanto aos 15 meses após aplicação dos tratamentos, os teores dos cátions básicos foram mais afetados que os componentes da acidez. Via de regra, a aplicação de gesso agrícola promoveu intensa lixiviação de Mg2+ e K+ nas camadas mais superficiais do solo, o que resultou no aumento da concentração dos nutrientes em profundidade. Referindo-se aos componentes da acidez, o Al3+ foi o componente mais alterado pela aplicação dos tratamentos, principalmente aos 15 meses após aplicação. Um resultado a ser destacado é que a ES com gesso aumentou os 9 teores de Al3+ em profundidade. Os teores de COXP e CO não foram afetados pelos tratamentos. As alterações nos atributos químicos do solo repercutiram sobre os atributos físicos. O diâmetro médio ponderado dos agregados e as proporções de macroagregados grandes foram mais influenciadas aos 15 meses após aplicação, em relação aos 7 meses, demonstrando a importância do tempo de reação dos materiais no solo sobre sua agregação. A Ds, a Pt e a Ma foram alteradas pelos tratamentos na camada de 0,40–0,60 m, diferentemente da Mi, que foi afetada nas camadas mais superficiais do solo (0–0,20 m). A retenção de água no solo foi sensível as alterações na estrutura do solo, principalmente quando os corretivos foram aplicados associados ao gesso agrícola. Deste modo, pode-se concluir que a dinâmica dos íons no solo pela correção da acidez e aplicação e gesso agrícola influencia os atributos físicos do solo, tanto em superfície como em profundidade. O aumento nos teores de Ca2+ e Mg2+ e a redução do Al3+ melhora a estrutura do solo, reduzindo sua Ds e aumentando sua Pt; e, a substituição de Al3+ por Mg2+ no complexo de troca do solo, decorrentes da aplicação da ES e do gesso agrícola influencia a retenção de água no solo. Sendo que a maior concentração do Mg2+ favorece a retenção. Os efeitos da correção da acidez do solo, independentemente do corretivo, e do gesso agrícola sobre a produtividade das culturas ocorre de maneira independente. Também, as culturas respondem de maneira distinta a correção da acidez e a gessagem. Todavia, o calcário calcinado foi o corretivo com maior eficiência agronômica, tanto quando aplicado isoladamente como quando associado ao gesso agrícola. / Soil acidity is an important factor that restricts agricultural production in the world. Acid soils have low pH values, high exchangeable aluminum (Al3 +) content and low availability of exchangeable calcium (Ca2+), magnesium (Mg2+) and potassium (K+). To correct the problems caused by the soil acidity, several materials can be used, with emphasis on carbonates and silicates of Ca and Mg. These products present distinctions as to their chemical composition and physical characteristics, which has repercussions on their reactivity on the soil. However, with the advent of no-till (NT), acidity correctives are applied to the soil surface, which restricts the correction of acidity in subsurface. In this context, the phosphogypsum is applied in association with acidity correctives. Although the phosphogypsum does not act on the active acidity of the soil, in subsurface it acts reducing the Al3+ contents and increasing the Ca2+ contents, which improves the root environment. The chemical management of the soil, through the application of correctives of acidity and of agricultural gypsum can alter the soil structure and the thermodynamic processes that occur in it. In this context, the general aim of this study was to evaluate the effects of soil acidity correctives [ground rock limestone (GRL), steel slag (SS) and calcined limestone (CL)], associated or not with soil physical and chemical attributes and crop productivity in NT. For this purpose, an experiment was carried out on a sandy-clay Typic Hapludox, at Ponta Grossa-PR. The treatments were the three soil acid correctives: GRL (3.8 Mg ha-1), SS (4.2 Mg ha-1) and CL (2.7 Mg ha-1), plus one control treatments (without acidity correction), associated or not with phosphogypsum (2.4 Mg ha-1). The corrective doses were calculated to raise the base saturation of the 0-0.20 m layer to 70%, based on their carbonate equivalents. The dose of phosphogypsum was calculated based on the soil clay content. Correctives and phosphogypsum were applied to the soil surface in August 2015. The crop rotation was corn (2015/16) – wheat (2016) – soybean (2016/17) – black oat (2017) – beans (2017/18). After the corn and wheat were harvested, at 7 and 15 months after the treatments, undisturbed and disturbed soil samples were collected. Undisturbed soil samples were collected in (i) monoliths, in the 0–0.05; 0.05–0.10 and 0.10–0.20 m layers, for evaluation of aggregation and aggregates stability; and in (ii) volumetric rings, in the 0–0.05; 0.05–0.10; 0.10–0.20; 0.20–0.40 and 0.40–0.60 m layers, to evaluate the soil bulk density (BD), total porosity (TP), macroporosity (Ma), microporosity (Mi) and soil water retention. The deformed samples were collected in the same collection layers of the volumetric rings to determine the soil acidity components (pH, H+Al and Al3+), exchangeable basic cations (Ca2+, Mg2+ and K+) and labile (POxOC) and total (OC) carbon contents. The yield crops was evaluated and used to determine the agronomic efficiency of the correctives and the phosphogypsum. Both at 7 and 15 months after application of treatments, the basic cations contents were more affected than the acidity components. As a rule, the application of phosphogypsum promoted intense Mg2+ and K+ leaching in the more superficial layers of the soil, which resulted in increased concentration of nutrients in depth. Referring to the components of acidity, Al3+ was the most altered component by the application of treatments, especially at 15 months after application. One result to be highlighted is that SS with phosphogypsum increased Al3+ contents in depth. The POcOC and OC contents were not affected by the treatments. The changes in the soil chemical attributes had repercussions on the physical attributes. The weight mean diameter of the aggregates and the proportions of large macroaggregates were more influenced at 15 months 11 after application, in relation to the 7 months, demonstrating the importance of the reaction time of the materials in the soil on their aggregation. BD, TP and Ma were altered by treatments in the layer of 0.40–0.60 m, while Mi was affected in the most superficial layers of the soil (0–0.20 m). The soil water retention was sensitive to changes in soil structure, especially when the correctives were applied associated with the phosphogypsum. In this way, it can be concluded that soil ion dynamics by the acidity correction and phosphogypsum application influences the physical attributes of the soil, both in surface and in depth. The increase in the Ca2+ and Mg2+ contents and the Al3+ reduction improve the soil structure, reducing its BD and increasing its TP; and, the substitution of Al3+ for Mg2+ in the soil exchange complex, due to the application of SS and phosphogypsum influences soil water retention. The higher concentration of Mg2+ favors retention. The effects of correcting soil acidity, regardless of the corrective, and the phosphogypsum on crop yield, occur independently. Also, crops respond differently to acidity correction and phosphogypsum application. However, the calcined limestone was the corrective with higher agronomic efficiency, both when applied alone and when associated with agricultural gypsum.

A acidez do solo é um sério problema que limita o crescimento radicular das culturas. A aplicação de calcário na superfície do solo visando à correção da acidez é utilizada em áreas cultivadas no sistema de plantio direto (SPD) já instalado. A amenização da acidez no subsolo devido à aplicação do calcário na superfície é influenciada pelo manejo da cobertura vegetal e pela adubação nitrogenada. Além disso, a calagem e a cobertura vegetal afetam os ciclos de C e de N devido à influência em atributos biológicos do solo, como estrutura e atividade microbiana, qualidade e quantidade de substrato disponível aos microorganismos decompositores. Os objetivos desse estudo foram avaliar o efeito da calagem e da cobertura de resíduos de aveia preta, com e sem adubação nitrogenada (i) nos atributos químicos e na especiação iônica da solução de um Latossolo Vermelho Distrófico, textura média, na nutrição e na produção de grãos de soja em experimento conduzido em Ponta Grossa-PR (25º10S, 50º05W) sob SPD; (ii) nos compartimentos de C e de N, no potencial de mineralização de N e na taxa de decomposição de aminoácidos; e (iii) estudar o efeito do pH inicial do solo e local de adição de resíduos de aveia preta na composição da solução do solo e no comportamento da comunidade microbiana. A calagem aumentou o pH do solo e os teores de Ca e Mg trocáveis e reduziu os teores de Al e Mn até 60 cm de profundidade, independentemente dos tratamentos de cobertura vegetal. A adição de N promoveu acidificação do solo. A maior parte do Al estava complexada com carbono orgânico dissolvido na solução do solo, ao contrário de Ca e de Mg, que estavam predominantemente na forma livre. A produção de grãos de soja aumentou de forma linear com a aplicação de calcário. A atividade microbiana, o potencial de mineralização de N e taxa de decomposição de aminoácidos foi estimulada devido ao aumento do pH do solo proporcionado pela calagem, principalmente na camada superficial. Aminoácidos liberados da decomposição inicial dos resíduos de aveia preta foram rapidamente consumidos pelos microorganismos do solo principalmente em valores altos de pH do solo. Portanto, a calagem superficial, o manejo da cobertura vegetal e a adubação nitrogenada interferiram na disponibilidade de nutrientes e na composição e atividade da biomassa microbiana em SPD. / Soil acidity is a serious problem in tropical and subtropical regions of the world reducing root growth and crop yield. Surface liming is a common practice to ameliorate soil acidity in areas under no-till system (NTS). The subsoil acidity amelioration, as a result of surface liming, is affected by cover crop residues as well as N fertilization. Liming and crop residues play important roles on C and N cycles due to changes in soil biological attributes, such as microbial community and activity, quantity and quality of substrate to microorganisms. The aims of this study were to evaluate the effects of surface liming and black oat residues, with or without N addition, on (i) soil chemical attributes, ionic speciation, soybean nutrition and yield of a loamy, kaolinitic, thermic Rhodic Hapludox in an experiment carried out in Ponta Grossa, state of Paraná, Brazil (25º10S, 50º05W) under NTS; (ii) C and N pools, potentially mineralizable N and decomposition rate of amino acids; and (iii) to evaluate the initial soil pH and black oat residues placement on soil solution composition and microbial behaviour. Surface liming increased soil pH and contents of Ca and Mg throughout soil profile, and also it reduced Al content to a 60 cm soil depth, regardless of cover crop treatments. The addition of N caused soil acidification. The Al content in soil solution was found mainly complexed to dissolved organic compounds, in contrast to Ca and Mg, which were found in a free form. Soybean yield was increased by lime rates. Due to soil pH increase, surface liming stimulated soil microbial biomass, potentially mineralizable N and amino acids decomposition rate, mainly at soil surface layer. Amino acids released from the initial decomposition of black oat residues were immediately used by soil microorganisms. Surface liming, cover crop residues and N fertilization affected nutrients availability and microbial biomass composition and activity under NTS.

A acidez do solo é um sério problema que limita o crescimento radicular das culturas. A aplicação de calcário na superfície do solo visando à correção da acidez é utilizada em áreas cultivadas no sistema de plantio direto (SPD) já instalado. A amenização da acidez no subsolo devido à aplicação do calcário na superfície é influenciada pelo manejo da cobertura vegetal e pela adubação nitrogenada. Além disso, a calagem e a cobertura vegetal afetam os ciclos de C e de N devido à influência em atributos biológicos do solo, como estrutura e atividade microbiana, qualidade e quantidade de substrato disponível aos microorganismos decompositores. Os objetivos desse estudo foram avaliar o efeito da calagem e da cobertura de resíduos de aveia preta, com e sem adubação nitrogenada (i) nos atributos químicos e na especiação iônica da solução de um Latossolo Vermelho Distrófico, textura média, na nutrição e na produção de grãos de soja em experimento conduzido em Ponta Grossa-PR (25º10S, 50º05W) sob SPD; (ii) nos compartimentos de C e de N, no potencial de mineralização de N e na taxa de decomposição de aminoácidos; e (iii) estudar o efeito do pH inicial do solo e local de adição de resíduos de aveia preta na composição da solução do solo e no comportamento da comunidade microbiana. A calagem aumentou o pH do solo e os teores de Ca e Mg trocáveis e reduziu os teores de Al e Mn até 60 cm de profundidade, independentemente dos tratamentos de cobertura vegetal. A adição de N promoveu acidificação do solo. A maior parte do Al estava complexada com carbono orgânico dissolvido na solução do solo, ao contrário de Ca e de Mg, que estavam predominantemente na forma livre. A produção de grãos de soja aumentou de forma linear com a aplicação de calcário. A atividade microbiana, o potencial de mineralização de N e taxa de decomposição de aminoácidos foi estimulada devido ao aumento do pH do solo proporcionado pela calagem, principalmente na camada superficial. Aminoácidos liberados da decomposição inicial dos resíduos de aveia preta foram rapidamente consumidos pelos microorganismos do solo principalmente em valores altos de pH do solo. Portanto, a calagem superficial, o manejo da cobertura vegetal e a adubação nitrogenada interferiram na disponibilidade de nutrientes e na composição e atividade da biomassa microbiana em SPD. / Soil acidity is a serious problem in tropical and subtropical regions of the world reducing root growth and crop yield. Surface liming is a common practice to ameliorate soil acidity in areas under no-till system (NTS). The subsoil acidity amelioration, as a result of surface liming, is affected by cover crop residues as well as N fertilization. Liming and crop residues play important roles on C and N cycles due to changes in soil biological attributes, such as microbial community and activity, quantity and quality of substrate to microorganisms. The aims of this study were to evaluate the effects of surface liming and black oat residues, with or without N addition, on (i) soil chemical attributes, ionic speciation, soybean nutrition and yield of a loamy, kaolinitic, thermic Rhodic Hapludox in an experiment carried out in Ponta Grossa, state of Paraná, Brazil (25º10S, 50º05W) under NTS; (ii) C and N pools, potentially mineralizable N and decomposition rate of amino acids; and (iii) to evaluate the initial soil pH and black oat residues placement on soil solution composition and microbial behaviour. Surface liming increased soil pH and contents of Ca and Mg throughout soil profile, and also it reduced Al content to a 60 cm soil depth, regardless of cover crop treatments. The addition of N caused soil acidification. The Al content in soil solution was found mainly complexed to dissolved organic compounds, in contrast to Ca and Mg, which were found in a free form. Soybean yield was increased by lime rates. Due to soil pH increase, surface liming stimulated soil microbial biomass, potentially mineralizable N and amino acids decomposition rate, mainly at soil surface layer. Amino acids released from the initial decomposition of black oat residues were immediately used by soil microorganisms. Surface liming, cover crop residues and N fertilization affected nutrients availability and microbial biomass composition and activity under NTS.