RESUMO: A acidez potencial do solo pode ser medida por dois métodos nos estados do Rio Grande do Sul (RS) e Santa Catarina (SC): índice SMP ou solução TSM (Tampão Santa Maria). A calibração destes métodos é feita pela incubação de solos por longos períodos (180 dias) com quantidades crescentes de CaCO3. A hipótese deste estudo é que é possível reduzir o período de incubação em solos usando uma base solúvel como o hidróxido de cálcio. O trabalho objetivou estimar a acidez potencial em um grupo de solos por meio de incubação úmida com Ca(OH)2 (curta) como alternativa ao método típico com CaCO3 (longa) e relacionar com os valores estimados pela equação utilizada pela CQFS-RS/SC (2016). Dez solos com textura arenosa e baixo conteúdo de matéria orgânica foram coletados a 0-20cm na região da Campanha Gaúcha e incubados por 180 dias com doses de CaCO3 equivalentes a 0, 25, 50, 75, 100, 125 e 150% da exigência de calcário estimada pela solução TSM para elevar o pH a 6,0 (longa). Os solos foram também incubados por 4 dias em estufa a 35ºC com 0,22mol L-1 de Ca(OH)2 em doses equivalentes ao CaCO3 (curta). A incubação curta do solo com Ca(OH)2 pode substituir a incubação longa com CaCO3. Além disso, a estimativa da acidez potencial utilizando a equação do CQFS-RS/SC (2016) superestimou a acidez potencial de solos com valores de pH em solução TSM inferiores a 6,0 neste estudo.

ABSTRACT: Potential soil acidity can be measured by two methods in the states of Rio Grande do Sul (RS) and Santa Catarina (SC): solution SMP or solution TSM (Buffer Santa Maria). Calibration of these methods is done by incubating soils for long periods (180 days) of CaCO3. The hypothesis of this study is that it is possible to reduce the incubation period in soils by using a soluble base such as calcium hydroxide. The study aimed to estimate potential acidity in a group of soils by moist incubation with Ca(OH)2 (short) as an alternative to the typical method with CaCO3 (long) and relate to the values estimated by the equation used by the Soil Chemistry and Fertility Commission of Rio Grande do Sul and Santa Catarina (CQFS-RS/SC; 2016). Ten soils with sandy texture and low organic matter content were collected at 0-20cm in the Campanha Gaúcha region of the state of RS and incubated for 180 days with doses of CaCO3 equivalent to 0, 25, 50, 75, 100, 125 and 150% of the lime requirement estimated by the solution TSM to raise to pH 6.0. Soils were also incubated for 4 days in an oven at 35ºC with 0.22mol L-1 Ca(OH)2 at doses equivalent to CaCO3. Short incubation of the soil with Ca(OH)2 may substitute long incubation with CaCO3. Also, estimating potential acidity using the equation of the CQFS-RS/SC (2016) overestimated potential acidity in soils with solution TSM pH values lower than 6.0 in this study.

Resumo: O objetivo deste trabalho foi avaliar o efeito das aplicações de dejetos líquidos de suínos no teor de Al trocável, na atividade e na distribuição das espécies químicas de Al na solução do solo. Amostras de um Argissolo foram obtidas de um experimento conduzido durante oito anos, com 19 aplicações de 0, 20, 40 e 80 m3 ha-1 de dejetos líquidos de suínos. As amostras de solo foram coletadas em camadas, para determinação do Al trocável e extração da solução do solo pelo método da pasta de saturação. Na solução, foram determinados as concentrações dos principais cátions e ânions, o carbono orgânico dissolvido e o pH. A distribuição das espécies químicas de Al e a atividade da espécie Al3+ foram obtidas pelo programa Visual Minteq. A aplicação de dejetos líquidos de suínos não altera o teor de Al trocável no solo e a atividade de Al3+ na solução do solo. A baixa atividade de Al3+ nas camadas superficiais não apresenta risco de toxidez para a maioria das culturas. A adição de dejetos líquidos de suínos aumenta a proporção das espécies AlHPO4 + e AlSO4 + na solução do solo, por incrementar a concentração de ligantes inorgânicos solúveis.

Abstract: The objective of this work was to evaluate the effect of pig slurry applications on the exchangeable Al content, activity, and distribution of Al chemical species in the soil solution. Soil samples of a Typic Hapludalf were obtained from an experiment conducted during eight years, with 19 applications of 0, 20, 40, and 80 m3 ha-1 pig slurry. The soil samples were collected in stratified layers to determine exchangeable Al content and to extract the soil solution by the saturated soil paste method. The concentrations of the main cations and anions, dissolved organic carbon, and pH in the soil solution were determined. The distribution of the chemical species of Al and the activity of the Al3+ species were obtained through the Visual Minteq software. The application of pig slurry does not change the exchangeable Al content in the soil and the Al3+ activity in the soil solution. The low Al3+ activity in the topsoil layers does not present risk of toxicity for most crops. Pig slurry applications increase the proportion of the AlHPO4 + and AlSO4 + species in the soil solution, by increasing the concentration of soluble inorganic ligands.

Resumo: O objetivo deste trabalho foi avaliar as formas de fósforo em folhas e suas relações com a composição do mosto e a produção em videiras cultivadas em um Argissolo Vermelho distrófico típico, com diferentes teores de P disponível. Dois experimentos foram realizados com cultivares de Vitis vinifera, um com uvas 'Tannat' e outro com 'Cabernet Franc'. O experimento 1 consistiu de dois vinhedos de 'Tannat', com os seguintes teores de fósforo no solo: V1, 11,8 mg kg-1 de P; e V2, 34,6 mg kg-1 de P. O experimento 2 consistiu de dois vinhedos de 'Cabernet Franc', com os seguintes teores de fósforo no solo: V1, 16,0 mg kg-1 de P; e V2, 37,0 mg kg-1 de P. Coletaram-se as folhas ao florescimento (FL) e ao início da maturação (IM), e, após a preparação delas, analisaram-se as formas de P. A produtividade e a composição do mosto foram avaliadas. A maior produtividade foi observada no V2 do experimento 1 e no V2 do experimento 2. O teor total de P e suas formas nas folhas ao FL e IM não apresentam relação com os parâmetros produtivos; no entanto, o teor de P total nas folhas apresenta relação com o teor de antocianinas no mosto de videiras 'Tannat'. Portanto, o fracionamento de P nas folhas não prediz a produtividade da videira nem a composição do mosto.

Abstract: The objective of this work was to evaluate phosphorus forms in grape leaves and their relationships with must composition and yield in grapevines grown in a Typic Hapludalf with different available P contents. Two experiments were carried out with Vitis viniferacultivars, one with 'Tannat' and the other with 'Cabernet Franc' grapes. Experiment 1 consisted of two vineyards of 'Tannat', with the following P content in the soil: V1, 11.8 mg kg-1 P; and V2, 34.6 mg kg-1 P. Experiment 2 consisted of two vineyards of 'Cabernet Franc', with the following P content in the soil: V1, 16.0 mg kg-1 P; and V2, 37.0 mg kg-1 P. Leaves were collected at flowering (FL) and veraison (V), and, after their preparation, P forms were evaluated. Yield and must composition were assessed. The highest yield was observed in V2 of experiment 1 and in V2 of experiment 2. Total P content and P forms in leaves at FL and V have no relationship with yield parameters; however, total P content in leaves has a relationship with anthocyanin content in the must of 'Tannat' grapevines. Therefore, P fractionation in leaves predicts neither grapevine yield nor must composition.

ABSTRACT Applications for long periods of organic animal waste as a source of nutrients to crops can contaminate the soil and the surface and subsurface waters. This study aimed to evaluate how the utilization of organic waste, after successive applications, affects P fractions in the soil and consequently environmental contamination. In an experiment conducted for 8 years, totaling 12 applications with pig slurry manure (PSM), liquid cattle manure (LCM), swine deep bedding (SDB), and mineral fertilizer (NPK), 460; 505; 1.111; and 535 kg P∙ha−1 were added to the soil through PSM, LCM, SDB, and NPK, respectively. In September 2012, soil samples were collected in the layers 0.0 – 0.04; 0.04 – 0.08; 0.08 – 0.12; 0.12 – 0.16; 0.16 – 0.20 m, prepared and subjected to a sequential chemical fractionation of P. The 12 applications of pig slurry, liquid cattle manure, swine deep bedding and NPK fertilizer for eight years (urea + triple superphosphate + potassium chloride) provided accumulations of P fractions in the soil that were above the necessary for a proper nutrition to plants considering the available P fractions (AER + organic NaHCO3 + inorganic NaHCO3) in the soil. In addition, they showed that the use of swine deep bedding, followed by pig slurry, means higher levels of available P fractions in the soil. In this sense, the establishment of a dosage of organic waste to meet the nitrogen need of crops is not an environmentally appropriate parameter. It may cause P accumulation in the soil, increased absorption ability of plants and soil support, contributing to environmental contamination.

ABSTRACT Cover crops grown alone or in association can take up different amounts of phosphorus (P) from the soil and accumulate it in different P-forms in plant tissue. Cover crop residues with a higher content of readily decomposed forms may release P more quickly for the next onion crop. The aim of this study was to evaluate the release of P forms from residues of single and mixed cover crops in agroecological no-till onion (Allium cepa L.) production. The experiment was conducted in Ituporanga, Santa Catarina (SC), Brazil, in an Inceptisol, with the following treatments: weeds, black oat (Avena sativa L.), rye (Secale cereale L.), oilseed radish (Raphanus sativus L.), oilseed radish + black oat, and oilseed radish + rye. Cover crops were sown in April 2013. In July 2013, plant shoots were cut close to the soil surface and part of the material was placed in litterbags. The bags were placed on the soil surface and residues were collected at 0, 15, and 45 days after deposition (DAD). Residues were dried and ground and P in the plant tissue was determined through chemical fractionation. The release of P contained in the tissue of cover crops depends not only on total P content in the tissue, but also on the accumulation of P forms and the quality of the residue in decomposition. The highest accumulation of P in cover crops occurred in the soluble inorganic P fraction, which is the fraction of fastest release in plants. Black oat had the highest initial release rate of soluble inorganic P, which became equal to the release rate of other cover crop residues at 45 DAD. Weeds released only half the amount of soluble inorganic P in the same period, despite accumulating a considerable amount of P in their biomass. The mixtures of oilseed radish + rye and oilseed radish + black oat showed higher release of P associated with RNA at 45 DAD in comparison to the single treatments.

Solos com baixo teor de argila e matéria orgânica apresentam baixa disponibilidade de enxofre (S) e, por isso, as culturas podem responder à adubação sulfatada. No entanto, a mobilidade de S no perfil do solo e sua deposição atmosférica pela água da chuva dificultam o estabelecimento do nível de suficiência do nutriente no solo. Este trabalho objetivou avaliar a resposta de culturas à adubação sulfatada e quantificar o S atmosférico depositado no solo pela água da chuva. Os cultivos avaliados (mamoneira, trigo, feijão-de-porco e milheto) foram realizados entre 2006 e 2009, em um Argissolo Vermelho distrófico arênico. As doses de S aplicadas em cada cultivo foram de 0, 5, 10 e 20 kg ha-1, utilizando-se gesso agrícola como fonte de S. Avaliaram-se a produção de matéria seca e o acúmulo de S na parte aérea do milheto e do feijão-de-porco, e a produção e o teor de S nos grãos de mamona e de trigo. Determinou-se o teor de S disponível no solo até 60 cm de profundidade e a deposição de S pelas precipitações. A maior produção de grãos da mamona e de matéria seca do segundo cultivo de feijão-de-porco foi obtida com aplicação de 14,5±0,35 kg ha-1 de S. Mesmo com teores de S abaixo dos níveis de suficiência, não houve respostas do trigo, do milheto e do primeiro cultivo de feijão-de-porco à adubação sulfatada. O aporte de S atmosférico ao solo foi de 4,5 kg ha-1 ano-1 e pode ter contribuído para a ausência de resposta desses cultivos.

Soils with low levels of clay and organic matter have low sulfur (S) availability. Therefore, crop yields may increase due to S fertilization. However, the mobility of S in the soil profile and its atmospheric deposition by rainwater make it difficult to establish the S sufficiency level in the soil. The objective of this study was to evaluate the response of crops to S fertilization and quantify the S atmospheric deposition in the soil via rainwater. The cultivations evaluated (castor bean, wheat, jack bean and millet) were performed between 2006 and 2009 in a Hapludalf. The S doses applied in each cultivation were 0, 5, 10 and 20 kg ha-1, using gypsum as a S source. The dry matter production and S accumulation were evaluated the in the shoots of millet and jack bean, and production and the S content were evaluated in castor bean and wheat. We also determined the level of available S in the soil to a depth of 60 cm and the S deposition by rainfall. The highest grain yield of castor bean and the highest dry matter yield in the second cultivation of jack bean were obtained with the application of 14.5±0.35 kg ha-1 S. Even with S content below the sufficiency levels, there was no response of wheat, millet and the first crop of jack bean to the S fertilization. The atmospheric input of S to the soil was 4.5 kg ha-1 year-1 and it may have contributed to the no response of these crops.

Em solos com baixos teores de argila e matéria orgânica pode haver menor disponibilidade de enxofre (S) e, por esse motivo, espera-se que a adubação sulfatada incremente a produção das culturas. O trabalho objetivou avaliar a resposta de culturas e a disponibilidade de S em solos com diferentes teores de argila e matéria orgânica, submetidos à adubação sulfatada. O experimento foi realizado em vasos em casa de vegetação no período de agosto de 2004 até janeiro de 2008. Foram realizados nove cultivos sucessivos de plantas em quatro tipos de solos, submetidos à aplicação de quatro doses de S. Avaliou-se a produção de matéria seca e o acúmulo de S na parte aérea das plantas e o teor do elemento disponível no solo das camadas 0 - 10 e 10 - 20 cm. As plantas do primeiro cultivo de milho e aveia preta aumentaram a produção de matéria seca com a aplicação de S, mas o aumento da produção do milho não teve relação com os teores de S disponível da camada 0 - 10 cm nos solos arenosos. Mesmo com teores de S disponível nessa camada abaixo dos níveis de suficiência, não houve resposta do girassol, feijão, soja e mamona à adubação sulfatada. A quantidade de S acumulada na parte aérea das plantas e o teor de S disponível no solo aumentaram com a aplicação do nutriente. Grande parte do S migrou para a camada de 10 - 20 cm, especialmente nos solos arenosos e, assim, o diagnóstico da sua disponibilidade deve ser realizado nas camadas subsuperficiais do solo.

Soils with low levels of clay and organic matter frequently had shown low sulfur (S) availability. Therefore, increases in crop yields trough sulfated fertilizations are expected. The objective of this work was to evaluate the response of crops and the S availability in soils with different contents of clay and organic matter submitted to sulfated fertilization. The experiment was carried out in pots in a greenhouse during the period from August 2004 to January 2008. Nine successive crops were cultivated in four classes of soils submitted to the application of four S levels. Dry matter yield and S accumulation in the shoot were evaluated. Soil samples from the soil layers of 0 - 10 cm and 10 - 20 cm were collected to quantify the available S content. Only the first cultivation of corn and black-oat increased the shoot dry matter yields due to sulfated fertilization. Besides, there was no relation between corn yield increases and the levels of available S from the soil layer of 0 - 10 cm in sandy soils. Even when the available S content in the soil layer of 0-10 cm was lower than the critical levels, no sulfate fertilization responses were observed when sunflower, bean, soybean and castor bean were cultivated. The amount of S accumulated in the shoots and the level of available S increased due to S fertilization. A large amount of sulfate also migrated to the soil layer of 10 - 20 cm, especially in sandy soils, and therefore, the diagnosis of S availability should be made in the subsurface soil layers.