Application of phosphorus fertilizer can lead to changes in soil test P and increase both labile and non-labile phosphorus pools. Sequential fractionation showed that the labile (H2O-P and NaHCO3-P) fractions significantly (P < 0.05) increased with the addition of phosphorus fertilizer across all sites. Significant increase was observed in the non-labile (NaOH-P, HCl-P and Residual-P) fractions during the accumulation phase. During the depletion phase, when no further P was added, the accumulated P in the labile P fractions declined but not to the original level. The rates of P application, soil properties, soil test P methods used and time effect all had significant effects on soil test P changes in the extraction experiment. Mehlich-3 extracted the greatest amount of P from the two depths and Olsen-P was intermediate while the smallest amount was extracted with water. The pattern of the rate of change in extractable P with P addition for the 0 – 7.5 cm depth was not site dependent as the results obtained at the different sites were similar. / October 2016

Made available in DSpace on 2015-04-11T13:55:48Z (GMT). No. of bitstreams: 1 Tainah Manuela Benlolo Barbosa.pdf: 537553 bytes, checksum: d58899718ec99b7434ac14e56255c928 (MD5) Previous issue date: 2012-07-04 / Fundação de Amparo à Pesquisa do Estado do Amazonas / The Phosphate fertilizers efficiency in tropical soils is mainly influenced by its solubility, particle size and chemical composition. This work aimed to evaluate the effect of different phosphorus (P) sources on the initial development and distribution of P-fractions in curauá seedlings. The experimental design was completely randomized with six treatments and twelve replications. The treatments evaluated the response of curaua supplying 250 mg dm-3 of P, using five P sources (triple superphosphate - TS, magnesium termophosphate - MT, Arad reactive rock phosphate - RP, Araxá rock phosphate - AP and phosphoric acid), plus treatment control (without P supply). The initial development of curauá is affected by different phosphorus sources, with greater magnitude for the triple superphosphate. The organic-P was the main fraction accumulated on curauá, regardless of P source used. The accumulation of this fraction is more expressive using low solubility P-sources / Este trabalho objetivou avaliar o efeito de diferentes fontes de fósforo (P) no desenvolvimento inicial e na distribuição das frações fosfatadas na parte aérea do curauá. O delineamento experimental foi inteiramente casualizado, com seis tratamentos e doze repetições. Os tratamentos constituíram da avaliação da resposta do curauá ao fornecimento de 250 mg dm-3 de P, testando-se cinco fontes de P (superfosfato triplo, termofosfato magnesiano, fosfato reativo de Arad, fosfato de Araxá e ácido fosfórico), mais o tratamento controle (sem fornecimento de P). O desenvolvimento inicial do curauá é afetado pelas diferentes fontes de P, com maior magnitude para o superfosfato triplo. A espécie acumulou P preferencialmente na fração orgânica, independente da fonte utilizada, porém, o acúmulo nessa fração é mais expressivo com fontes de baixa solubilidade.

The issue of phosphorus in sediments of small watercourses and phosphorus forms are often out of interest, unlike phosphorus and its forms in sediments of water reservoirs. The thesis is focused on the development and evaluation of methods for the determination of total phosphorus by modifying commonly used methods and evaluation of methods for the determination of selected forms of phosphorus in small watercourses sediments. Over 1,152 analyses of sediment samples collected in four seasons and four locations and in three paralell determinations were done. The total phosphorus in the sediments was assessed by four methods, further 7 other forms of phosphorus were evaluated by one to three methods, according to different forms of phosphorus. The data file was subjected to statistical analysis. The aim of statistical analysis was to evaluate phosphorus concentrations, depending on the used method. Additional aim of statistical analysis was to observe dependencies of phosphorus concentrations on metals and identify the impact of periods and locations on the concentration of phosphorus.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The knowledge of P dynamics in grassland ecosystems may be important to prescription of changes caused by the addition of different sources of phosphate fertilizers in the P forms of soil, dry matter production and botanical composition of natural grasslands. The objective of this work was to evaluate the dynamics of P (a) the availability and forms of P; (b) total dry matter and contributions in dry matter and (c) dilution curves of P content from tissue of main species of natural grasslands after the application of different phosphate sources in three soil types under natural grasslands with or without historical of P applications. Treatments were P applications as Gafsa rock phosphate, simple superphosphate, triple superphosphate and control, arranged in randomized blocks with three replicates. In two experiments located in the city of Candiota - RS (Ultisol and Entisol), 100 kg ha-1 P2O5 were applied in September 2010. In the experiment of Santa Maria - RS (Alfisol), 180, 90, 100 e 100 kg ha-1 P2O5 were applied in 1997, 1998, 2002 and 2010, respectively, which represent 470 kg ha-1 P2O5. The soil samples (0-10 cm) and herbage mass were evaluated in the spring and summer after applied the last treatment in each experiment. The Gafsa rock phosphate showed a potential to increase P availability in soils with low calcium content in natural grasslands, but increases were higher when superphosphate was used. The application of phosphate fertilizers in soils under grasslands increases the importance of inorganic fractions of labile P to the available P to plants, making them less dependent on the mineralization of organic fractions. The P fertilization response was higher where annual species occurrence prevailed. In pastures with historical of fertilization, contribution of main species to the total dry mass of pasture had changed. In Candiota city, species did not grow by a severe drought. In Santa Maria, species as Paspalum notatum, Aristida laevis and other plants aggregated as Other Species had increased biomass and P tissue content was diluted over the periods. The specie Eustachys ulignosa had responded in biomass to soluble phosphate additions. The evaluated phosphates sources did not alter the N content in the tissue of grassland species. / O conhecimento da dinâmica do fósforo nos ecossistemas campestres pode ser importante para a prescrição das alterações provocadas pela adição de diferentes fontes de fertilizantes fosfatados sobre as formas de P no solo, na produção de matéria seca e na composição botânica das pastagens naturais. O objetivo do presente trabalho foi avaliar a influência da dinâmica do P (a) na disponibilidade e formas de P no solo; (b) na massa total de forragem e as contribuições de massa seca e (c) curvas de diluição de P no tecido das principais espécies componentes das pastagens naturais submetidas à aplicação de diferentes fontes de fosfato em três solos com e sem histórico de fertilização fosfatada. Os tratamentos consistiram na aplicação de P nas formas de hiperfostado de Gafsa, superfosfato simples, superfosfato triplo e testemunha, arranjados em blocos casualizados com três repetições. Nos dois experimentos instalados em Candiota (Luvissolo Úmbrico e Neossolo Litólico), foram aplicados 100 kg ha-1 P2O5 em setembro de 2010. No experimento de Santa Maria (Argissolo Vermelho) foram aplicados 180, 90, 100 e 100 kg ha-1 P2O5 nos anos de 1997, 1998, 2002 e 2010, respectivamente, totalizando 470 kg ha-1 de P2O5. As coletas de solo (camada 0-10 cm) e as massas de forragem foram avaliadas no período primavera-verão, após a última aplicação dos tratamentos em cada experimento. O hiperfosfato de Gafsa demonstrou ter potencial de disponibilização de P em solos ácidos com baixo teor de cálcio sob pastagens naturais, mas a disponibilização de P obtida com os superfosfatos foi maior. A aplicação de fertilizantes fosfatados em solos pobres sob pastagens naturais aumenta a importância das frações inorgânicas lábeis de P na disponibilização de P para as plantas, tornando-as menos dependentes da mineralização das frações orgânicas. A resposta da pastagem natural à fertilização fosfatada foi maior onde havia significativa contribuição de espécies anuais. O histórico de adição de fertilizantes fosfatados solúveis alterou a contribuição das principais espécies na massa seca total das pastagens naturais. Em Candiota, as espécies não apresentaram crescimento em função de forte estiagem. Em Santa Maria, as espécies Paspalum notatum, Aristida laevis e o componente Outras Espécies aumentaram a biomassa aérea e diluíram P do tecido ao longo dos períodos avaliados. A espécie Eustachys ulignosa respondeu a adição de fosfato solúvel. As fontes de fosfatos avaliados não alteraram o teor de N no tecido das plantas.

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