Resumo O objetivo deste trabalho foi avaliar alterações nas propriedades químicas do solo e o limite crítico ambiental para o fósforo (LCA-P), em vinhedos da região sul do estado de Santa Catarina, Brasil. Amostras de solo foram coletadas às profundidades do solo 0-5, 5-10, 10-20 e 20-40 cm, em vinhedos com 22, 36 e 60 anos de idade, e em uma área de mata nativa adjacente utilizada como referência. Os seguintes parâmetros foram analisados: granulometria, pH em água, e teores trocáveis de Al, para cálculo de acidez potencial e saturação por Al; e teores disponíveis de P e K e teores trocáveis de Ca e Mg, para determinação de saturação por bases, capacidade de troca de cátions e matéria orgânica do solo (MOS). Em comparação ao solo da mata, os solos dos vinhedos apresentaram aumento nos valores de pH, nos níveis de P, K, Ca, Mg, Cu, Zn e MOS, e na saturação por bases, além de redução na saturação de Al, com efeitos mais acentuados nas áreas com maior tempo de cultivo. Os vinhedos da região sul de Santa Catarina apresentam alterações nas propriedades químicas do solo, com o tempo, e teores de P acima do LCA-P, pelo menos em uma das camadas do solo.

Abstract The objective of this work was to evaluate changes in the soil chemical properties and the critical environmental limit for phosphorus (CEL-P) in vineyards, in the southern region of the state of Santa Catarina, Brazil. Soil samples were collected at 0-5, 5-10, 10-20, and 20-40 cm soil depths, in vineyards aged 22, 36, and 60 years, and in the area of an adjacent native forest. The following parameters were analyzed: granulometry, pH in water, and exchangeable Al levels, to obtain potential acidity and Al saturation; and available levels of P and K, and exchangeable levels of Ca and Mg, to determine base saturation, cation exchange capacity; and soil organic matter (SOM). In comparison with the forest soil, the vineyard soils showed increased pH values, P, K, Ca, Mg, Cu, Zn, and SOM levels, and base saturation, as well reduced Al saturation, with more accentuated effects in areas with the longest cultivation time. The vineyards show changes in soil chemical properties with time and P levels above the CEL-P, at least in one of the soil layers.

ABSTRACT: This study evaluated P pools after nine years of successive application of either pig slurry (PS) or deep pig litter (DL) in a no-till Ultisol from southern Brazil. The experiment was established in Dec 2002 with the treatments control, application of 90 and 180 kg N ha−1 N as PS and as DL. In Mar 2010, soil samples were taken at six layers up to 30 cm deep. Total organic and inorganic P were assessed by the ignition method, and P compounds classes were evaluated by 31P-NMR spectroscopy. Total soil P increased proportionally with the P amount applied via DL and PS. Only DL application increased soil organic P, mainly at the highest dose and in the uppermost soil layers. The application of high doses of manure to these soils under no-till to meet crop N demands significantly increased P accumulation at the soil surface, especially with DL. This, in turn, increases the risk of contamination of water bodies due to P transfer from soil to rivers via runoff. The ignition method overestimates organic P compared to P-NMR. The highest proportion of organic P estimated by the ignition and P-NMR methods, at surface layers in the control suggests that inorganic P is added to the plots treated, increasing inorganic P and decreasing organic P. Moreover, with no P additions to the control, inorganic soil P is removed by plants, causing an apparent increase in the organic P proportion.

RESUMO: A cebola é uma importante cultura vegetal, cultivada predominantemente sob sistema de preparo convencional. Como alternativa, o sistema de plantio direto de hortaliças utiliza culturas de cobertura para formar uma camada de biomassa, o que melhora os atributos físicos, químicos e biológicos do solo. Com o objetivo de entender a interação de culturas de cobertura micorrízicas e não-micorrízicas, atividade da fosfatase ácida e disponibilidade e absorção de fósforo do solo pelas plantas, foi realizado um experimento em sistema de plantio direto de hortaliças com a cultura da cebola em Ituporanga, sul do Brasil. Os tratamentos foram: aveia preta (Avena strigosa); centeio (Secale cereale); nabo forrageiro (Raphanus sativus); centeio + nabo forrageiro; aveia preta + nabo forrageiro e um controle com vegetação espontânea. Além disso, duas outras parcelas, uma área em sistema de preparo convencional e uma floresta, ambas adjacentes ao experimento, foram avaliadas. Medimos a biomassa da cultura de cobertura, o rendimento de cebola, a atividade de fosfatase ácida e o fósforo extraído por resina no solo, bem como o conteúdo de fósforo da parte aérea e da raiz e a colonização das raízes em plantas de cobertura, plantas espontâneas e cebolas. Os tratamentos com plantas de cobertura apresentaram a maior biomassa de culturas de cobertura e rendimento de cebola. A atividade de fosfatase ácida e fósforo disponível no solo foram maiores nas parcelas de plantio direto do que na área convencional. A presença de nabo forrageiro, uma planta não micorrízica, foi associada a reduções na colonização de raízes de centeio e cebola por fungos micorrízicos arbusculares. As áreas de plantio direto com plantas de cobertura ou plantas espontâneas no inverno acumularam mais fósforo do que as áreas com preparo convencional. O sistema convencional de lavoura mostrou efeitos adversos para a maioria dos atributos do solo, como mostra a Análise de Componentes Principais.

ABSTRACT: Onion is an important vegetable crop, predominantly grown under conventional tillage system management. Alternatively, the vegetable no-tillage system uses cover crops to form a residue layer, which improves soil physical, chemical, and biological attributes. Aiming to understand the interaction of mycorrhizal and non-mycorrhizal cover crops, phosphatase activity, and soil phosphorus availability and uptake by plants, a no-tillage vegetable production system experiment with onion was carried out in Ituporanga, Southern Brazil. The treatments were black oats (Avena strigosa); rye (Secale cereale); oilseed radish (Raphanus sativus); rye + oilseed radish; black oats + oilseed radish, and a control with spontaneous plants. Additionally, two plots, a conventional tillage system area and a forest, both adjacent to the experiment, were evaluated. We measured cover crop biomass, onion yield, acid phosphatase activity, and resin-extracted phosphorus in the soil, shoot and root phosphorus content, and root colonization in cover crops, spontaneous plants, and onions. The treatments with cover crops had the highest plant biomass in winter and onion yield. Available soil phosphorus and acid phosphatase activity were higher in no-tillage plots than in the conventional tillage system area. The presence of non-mycorrhizal oilseed radish was associated with decreased colonization of rye and onion roots by arbuscular mycorrhizal fungi. No-tillage areas with cover crops or spontaneous plants in winter accumulated more phosphorus than conventional tillage system areas. The conventional tillage system showed adverse effects on most soil attributes, as shown by a Principal Component Analysis.

Objetivou-se avaliar os teores de carbono orgânico total (COT) e carbono das frações oxidáveis em agregados biogênicos e fisiogênicos em áreas com aplicação de dejeto líquido de suínos (DLS) e cama sobreposta de suínos (CSS). Após 10 anos do uso de dejetos suínos (DS) na sucessão aveia/milho, coletaram-se amostras indeformadas de solo nas camadas de 0-5 e 5-10 cm, nos tratamentos sem aplicação de DS (testemunha), com aplicação de DLS e CSS em dose equivalente a uma e duas vezes a recomendação de N para o milho e aveia, respectivamente. Os agregados foram separados conforme a via de formação em biogênicos e fisiogênicos. Em seguida, estes agregados foram separados em macro, meso e microagregados. Nestes agregados determinaram-se o COT e apenas nos macroagregados para o C das frações oxidáveis (F1, F2, F3 e F4). A aplicação de DLS aumenta os teores de COT nos microagregados enquanto que o uso da CSS aumenta o conteúdo de COT nos macroagregados. O uso de CSS por longo tempo aumenta o carbono lábil (F1) e recalcitrante (F4) em comparação aos DLS e a testemunha. As frações de carbono oxidáveis permitiram evidenciar diferenças entre os agregados biogênicos e fisiogênicos, sendo maiores nos agregados biogênicos.

The objective of this study was to evaluate the total organic carbon (TOC) and carbon contents of the oxidizable fractions in biogenic and physicogenic aggregates in areas with pig slurry (PS) and deep litter (DL). After 10 years of use of pig manure (PM) in a crop succession with black oat/maize, undisturbed soil samples were collected in the 0-5 and 5-10 cm layers, in the treatments without PM (control) application, with application of PS and DL at a dose equivalent to one and two times the N recommended for maize and black oat, respectively. The aggregates were separated according to the biogenic and physicogenic formation pathway. Then, these aggregates were separated into macro, meso and microaggregates. In these aggregates the TOC was determined in the macro, meso and microaggregates and only in the macroaggregates for the C of the oxidizable fractions (fractions F1, F2, F3 and F4). Application of PS increases the TOC contents in the microaggregates while the DL increases TOC in macroaggregates. The use of DL for a long time increases the labile carbon (F1) and recalcitrant carbon (F4) in comparison to PS and control. Oxidizable carbon fractions showed differences between biogenic and physicogenic aggregates, being greater in the biogenic aggregates.

Resumo: O objetivo deste trabalho foi avaliar a produtividade e a composição do mosto de videiras 'Cabernet Sauvignon' e 'Chardonnay' submetidas a aplicações de fósforo em solo de região de altitude no Sul do Brasil, durante três safras. Os experimentos 1 e 2 foram realizados em vinhedos comerciais de 'Cabernet Sauvignon' e de 'Chardonnay', respectivamente, no município de Água Doce, na região Meio-Oeste do estado de Santa Catarina. O solo dos dois vinhedos foi classificado como Cambissolo Húmico. A fonte de P utilizada foi o superfosfato triplo (45% de P2O5). De 2011 a 2013, no florescimento, foram aplicados 0, 10, 20, 40 e 80 kg ha-1 de P2O5 na projeção da copa, na superfície do solo, sem incorporação, em ambos os vinhedos. Avaliaram-se concentração de P no solo e na folha, variáveis de produção e qualidade do mosto. O incremento na disponibilidade de P diminuiu os valores de acidez total titulável e de ácido tartárico no mosto da videira 'Cabernet Sauvignon' na safra de 2013/2014 e aumentou os valores de pH e sólidos solúveis totais no mosto da videira 'Chardonnay' na safra de 2011/2012. A aplicação de fósforo no solo aumenta os níveis de fósforo disponível, mas não resulta em maiores produtividades das videiras 'Cabernet Sauvignon' e 'Chardonnay'.

Abstract: The objective of this work was to evaluate the yield and must composition of 'Cabernet Sauvignon' and 'Chardonnay' grapevines subjected to phosphorus applications to a soil from a high-altitude region of Southern Brazil, during three crop seasons. Experiments 1 and 2 were carried out in 'Cabernet Sauvignon' and 'Chardonnay' commercial vineyards, respectively, in the municipality of Água Doce, located in the Midwestern region of the state of Santa Catarina. The soil from the two vineyards was classified as a Typic Humicryept. The used source of P was triple superphosphate (45% P2O5). From 2011 to 2013, at flowering, a total of 0, 10, 20, 40, and 80 kg ha-1 P2O5 were applied in the crown projection area, to the soil surface, without incorporation, in both vineyards. Soil and leaf P concentration, yield parameters, and must quality were evaluated. The increase in P availability decreased total titratable acidity and tartaric acid in the must of the 'Cabernet Sauvignon' grapevine in the 2013/2014 crop season and increased pH and total soluble solids in the must of the 'Chardonnay' grapevine in the 2011/2012 crop season. Phosphorus application to the soil increases the levels of available phosphorus, but does not result in higher yields for 'Cabernet Sauvignon' and 'Chardonnay' grapevines.

RESUMO: A biomassa microbiana é determinante na dinâmica da matéria orgânica do solo e sua atividade é um indicador de qualidade do solo em agroecossistemas, refletindo mudanças em práticas de manejo e em condições ambientais. Avaliou-se o efeito de culturas de cobertura de inverno, solteiras ou consorciadas, sobre atributos químicos do solo, carbono da biomassa microbiana (CBM), respiração basal (RB), quociente metabólico (qCO2) e atividade das enzimas urease, β-glucosidase e FDA, bem como o rendimento da cebola em um sistema de plantio direto. O solo é um Cambissolo Húmico alumínico, os tratamentos foram testemunha com vegetação espontânea, cevada, centeio, nabo forrageiro (NF), NF + centeio e NF + cevada. Realizaram-se cinco coletas de amostras de solo (0-10 cm) entre junho a dezembro. Não houve diferenças entre os tratamentos para CBM e RB, e os maiores valores para esses atributos ocorreram em junho, quando as plantas de cobertura estavam em seu estágio inicial. Embora o qCO2 não tenha sido afetado por nenhum tratamento, ele variou entre os períodos de amostragem, com valores entre 0,62 e 10 µg de C-CO2 mg-1 MBC h-1, indicando um ambiente de baixo ou nenhum estresse. As culturas de cobertura tiveram pouca influência na atividade enzimática, mas o FDA foi reduzido em áreas com cultivos solteiros de cevada ou centeio. O rendimento médio de cebola nos tratamentos com culturas de cobertura foi de 13,01 (Mg ha-1), mais alto que no tratamento controle.

ABSTRACT: Microbial biomass is a driving force in the dynamics of soil organic matter, and microbial activity is an indicator of soil quality in agroecosystems, reflecting changes in management practices and environmental conditions. We evaluated the effect of monoculture and intercropped winter cover crops on soil chemical attributes, microbial biomass carbon (MBC), basal respiration (BR), metabolic quotient (qCO2), urease, β-glucosidase, and fluorescein diacetate (FDA) hydrolysis activity, as well as onion yield in a no-tillage system. Soil is a Typic Humudept, and treatments were control with spontaneous vegetation, barley, rye, oilseed radish (OR), OR + rye, and OR + barley. The soil was sampled (0-10 cm) five times between June and December. There were no differences among treatments for MBC and BR, and the highest values for those attributes occurred in June, when cover plants were in their initial stage. Although, qCO2 was not affected by any treatment, it varied among sampling periods, ranging from 0.62 to 10 µg C-CO2 mg-1 MBC h-1, indicating a low- or no stress environment. Cover crops had little influence on enzyme activity, but FDA was lowered in areas with single crops of barley and rye. Average onion yield in cover crops treatments was 13.01 (Mg ha-1), 30-40% higher than in the control treatment.

ABSTRACT It is common for vineyards in regions of high altitude to have high organic matter content in soil. Furthermore, reduced miner alization of organic matter and decomposing residues is expected because of the low temperatures. Thus, soils may not provide enough mineral nitrogen (N) to meet the needs of the grapevines and so the application of N sources is necessary, but may affect yield and must composition. The study aimed to evaluate yield and must composition of grapevines subjected to N application in soil with high organic matter content and the relationship with temperature and rainfall. The study was conducted in crops sea sons 2011/12, 2012/13 and 2013/14 in a vineyard located in the city of Água Doce, state of Santa Catarina, southern Brazil. The treatments consisted of N doses (0, 20, 40, 80 and 120 kg N ha-1) supplied via urea. Leaves opposite to the cluster were collected at full flowering and at veraison. Afterwards, the leaves were dried, ground and submitted to N analysis. Parameters of yield and must composition were evaluated. The dose of maximum technical efficiency in Cabernet Sauvignon grapevines was reached with 46 kg N ha-1 year-1 in crop season 2012/13. Leaf N content was a sensitive parameter to the application of N doses in the soil and underwent seasonal variation in relation to rainfall distribution. The N doses reduced total soluble solids (TSS) contents in the must. Based on principal component analysis, we found a correlation between total N content in leaf and accumulated rainfall, as well as between yield and temperature.

RESUMEN Los viñedos ubicados en regiones altas poseen suelos con alto contenido de materia orgánica. Sin embargo, debido a la baja temperatura se espera menor mineralización de la materia orgánica. De esta forma, los suelos pueden proporcionar menos cantidad de nitrógeno (N) mineral, respecto a los requerimientos de la vid. Por eso, es necesaria la aplicación de nitrógeno que puede afectar la productividad de la vid y la composición de la uva. Este estudio tuvo como objetivo evaluar la productividad y la composición del mosto de la vid sometido a la aplicación de N en suelos con alto contenido de materia orgánica y la relación con la temperatura y la pluviometría. El estudio fue realizado durante las campañas de los años 2011/12, 2012/13 y 2013/14, en un viñedo ubicado en el municipio de Agua Doce, Santa Catarina, región sur de Brasil. Los tratamientos fueron diferentes dosis de N (0, 20, 40, 80 e 120 kg N ha-1), suministrados con urea. La dosis de máxima eficiencia técnica en la vid Cabernet Sauvignon fue alcanzada con 46 kg N ha-1 año-1 en suelos con alto contenido de materia orgánica. El contenido de nitrógeno en las hojas fue un parámetro sensible a la aplicación de dosis de N en el suelo es sensible a la distribución de las lluvias. El N reduce el contenido de sólidos solubles totales en el mosto. Con base en los principales componentes analizados, los resultados indican una correlación entre el contenido de nitrógeno total en las hojas y la precipitación acumulada, así como entre los rendimientos y la temperatura.

ABSTRACT Successive applications of swine manure can promote changes in soil physical attributes, with emphasis on the soil aggregation pathways. The objective of this work was to separate and quantify the aggregates according to their training path and to evaluate the stability of these aggregates in an area with a history of applications of pig slurry (PS) and deep litter (DL) in no-tillage system (NTS). After 10 years of use swine manure (SM) in oat/corn succession under NTS, undisturbed soil samples were collected in the 0-5 and 5-10 cm layers, in the treatments without SM (control), with application of PS and DL at doses equivalent to one and two times the recommended N for corn and oats (PS1X, PS2X, DL1X and DL2X, respectively). The aggregates were separated according to their morphological patterns and biogenic and physicogenic formation pathways. Then, weighted average diameter (WMD) of the aggregates and the distribution of the aggregates in the diameter classes for macroaggregates (8.0>Ø ≥2.0 mm), mesoaggregates (2.0>Ø ≥0.25 mm) and microaggregates (Ø<0.25 mm) in each type of aggregate were evaluated. The addition of SM increased the formation of biogenic aggregates. In the control area, the formation pathway of physicogenic aggregates prevails. The application of PS did not alter the WMD and the macroaggregates in relation to the control, while the application of DL increased these parameters when compared to the PS and control treatments.

RESUMO Aplicações sucessivas de dejetos suínos podem promover mudanças nos atributos físicos do solo, com ênfase nas vias de formação dos agregados solo. O objetivo deste trabalho foi separar e quantificar os agregados conforme sua via de formação e avaliar a estabilidade desses agregados em área com histórico de aplicações de dejeto líquido de suínos (DLS) e cama sobreposta de suínos (CSS), em sistema plantio direto (SPD). Após 10 anos do uso de dejetos suínos (DS) na sucessão aveia/milho sob SPD, coletaram-se amostras indeformadas de solo nas camadas de 0-5 e 5-10 cm, nos tratamentos sem DS (testemunha), com aplicação de DLS e CSS em doses equivalentes a uma e duas vezes a recomendação de N para o milho e a aveia (DLS1X, DLS2X, CSS1X e CSS2X, respectivamente). Os agregados foram separados conforme os seus padrões morfológicos e vias de formação em biogênicos e fisiogênicos. Em seguida, avaliaram-se o diâmetro médio ponderado (DMP) dos agregados e a distribuição dos agregados nas classes de diâmetro para macroagregados (8,00 > Ø ≥ 2,0mm), mesoagregados (2,0 > Ø ≥ 0,25mm) e microagregados (Ø < 0,25mm), em cada tipo de agregado. A adição de dejetos suínos aumentou a formação de agregados biogênicos. Na área testemunha prevalece a via de formação de agregados fisiogênicos. A aplicação de DLS não alterou o DMP e os macroagregados em relação à testemunha, enquanto a aplicação de CSS aumentou esses parâmetros quando comparada aos tratamentos DLS e Testemunha.

ABSTRACT The use of cover crops and poultry manure (PM) is an alternative to reduce the use of synthetic inputs and can contribute to the nutrient cycling in onions ( Allium cepa L.) grown under a no-tillage system. However, this management practice may contribute to an increase in N2O emissions to the atmosphere. The aims of this study were to evaluate the immediate effect on N2O emissions of adding PM onto cover crop residues and to verify the effect of different no-tillage systems on N2O emissions. Two studies (laboratory and field) were conducted with the addition of oilseed radish (OR), black oat (BO), and weed (WD) residues with and without PM under a no-tillage (NT) system. Emission of N2O (kg ha-1) was influenced by the different residue-management systems and was higher in treatments with OR residues (2.96 ± 0.67 kg ha-1 for OR and 5.28 ± 1.04 kg ha-1 for OR + PM). The other treatments behaved similarly with emissions of approximately 1.91 ± 0.17 kg ha-1 of N-N2O. The highest N2O emissions in the field study were found within the first 15 days and represented 50.3 % of the average emissions. Poultry manure showed high emissions when the cover crop was OR, but not when it was BO and WD.

ABSTRACT Carbon (C) and nitrogen (N) content in granulometric fractions of soil organic matter (SOM) are sensitive indicators of soil quality changes caused by management systems. This study evaluated the C and N content in granulometric fractions of SOM of aggregates, an Inceptisol under onion grown in no-till vegetable farming systems (NTVFS) and conventional tillage systems (CTS), comparing them to a secondary forest. Treatments consisted of soil cover crops, monocropped and intercropped with onions grown under NTVFS: spontaneous vegetation, 100% black oats; 100% rye; 100% oilseed radish; oilseed (14%) + rye (86%) intercrop and oilseed (14%) + oats (86%) intercrop. The same evaluations were also performed in an area with onions grown under CTS for ± 37 years, and in secondary forest (± 30 years). Undeformed soil samples were collected from 0-5, 5-10, and 10-20 cm deep soil layers, and aggregates were subsequently separated (8.00 mm > Ø ≥ 2.0 mm). Organic C (OC) and N of the granulometric fractions contents were quantified in aggregates, which were subdivided into particulate fractions (POC and PN) and mineral-associated fractions (OCam and Nam). NTVFS promoted protection of SOM at the 0-5 cm depth compared to CTS, as a result of higher POC content. Intercropped oats+oilseed and spontaneous vegetation contributed to an increase in PN content compared to all other treatments under NTVFS. Monocropped and intercroppped oilseed radish caused an increase in Nam, which was more effective than OCam to indicate differences among the systems. Conversion of areas from CTS to NTVFS promotes increases in POC and PN content in the upper soil layer. NTVFS improves the quality of aggregates, and it may reduce damage caused by CTS.

RESUMEN El contenido de carbono (C) y nitrógeno (N) en las fracciones granulométricas de la materia orgánica del suelo (MOS) es un indicador sensible de los cambios en la calidad del suelo causados por los sistemas de manejo. Este estudio evaluó el contenido de Cy N en fracciones granulométricas de la MOS de agregados, en un Inceptisol bajo cebolla cultivada en sistema de cultivo de vegetales sin labranza (SCVSL) y sistema de labranza convencional (SLC), comparándolos con un bosque secundario. Los tratamientos consistieron en cultivos de cobertura del suelo, monocultivos y consorciados con cebollas cultivadas bajo SCVSL: vegetación espontánea, 100% de avena negra; 100% de centeno; 100% nabo forrajero; consorcio de nabo (14%) + centeno (86%), consorcio de nabo (14%) + avena (86%). Las mismas evaluaciones se realizaron en un área con cebollas cultivadas bajo SLC durante ± 37 años, y en un bosque secundario (± 30 años). Se recogieron muestras de suelo no deformadas de capas de suelo de 0-5, 5-10 y 10-20 cm de profundidad, y los agregados se separaron posteriormente (8.00 mm> Ø ≥ 2.0 mm). Las cantidades de C orgánico (CO) y N de las fracciones granulométricas se cuantificaron en agregados, que se subdividieron en fracciones particuladas (PCO y PN) y fracciones asociadas con minerales (COam y Nam). SCVSL promovió la protección de MOS a una profundidad de 0-5 cm en comparación con SLC, como resultado de un mayor contenido de POC. La avena consorciada con nabo y la vegetación espontánea contribuyeron a un aumento en el contenido de PN en comparación con todos los otros tratamientos bajo SCVSL. El nabo forrajero en monocultivo y consorciado causó un aumento en Nam, que fue más efectivo que el COam para indicar diferencias entre los sistemas. La conversión de áreas de SLC a SCVSL promueve aumentos en el contenido de PCO y PN en la capa superior del suelo. SCVSL mejora la calidad de los agregados, y puede reducir el daño causado por SLC.

ABSTRACT The present study aimed to evaluate the accumulation and distribution of Cu and Zn fractions in the profile of an Inceptisol by application of fungicides with a previous history of apple cultivation in southern Brazil. Stratified soil samples (0.0 – 0.025 m, 0.025 –0.050 m, 0.05 – 0.10 m, 0.10 – 0.15 m, 0.15 – 0.20 m and 0.20 – 0.40 m depth) were collected in two apple orchards (8 years old and 18 years old), and in a native pasture area adjacent to the orchards. The soil was subjected to analysis of physical and chemical properties and to chemical fractionation of Cu and Zn. The fractions of soluble, exchangeable, organic, residual and total Cu and Zn accumulated in the topsoil (0.0 – 0.025 m) of the orchards, being higher in the orchard cultivated for 18 years. Most Cu, especially in the topsoil of the 18 years old orchard, accumulated in the less stable organic fraction, which can potentiate toxicity to plants and transfer Cu e Zn to ground water. In deeper layers, Cu was also distributed in the residual and mineral fractions, which are more stable. Most Zn in the soil of the apple orchards was distributed in the mineral and residual fractions, which have low mobility and low potential toxicity to plants.

RESUMEN Se evaluaron los niveles de nitrógeno total (NT) y N de las sustancias húmicas (SH) de la materia orgánica en agregados de suelo cultivado con cebolla bajo siembra directa de hortalizas (SDH) y sistema de preparación convencional (SPC), comparando con un área de bosque. Los tratamientos evaluados fueron: vegetación espontánea; 100% avena; 100% centeno; 100% nabo; cultivos asociados de nabo (14%) + centeno (86%); cultivos asociados de nabo (14%) + avena (86%); área bajo SPC de cebolla (±37 años) y de bosque secundario de ±30 años). Cinco años después de la implantación del SDH fueran recogidas muestras no disturbados del suelo en las capas 0-5, 5-10 y 10-20 cm y obtenidos los agregados (entre 2,0 y 8,00 mm). En estos se determinaron los niveles de NT y el N de las SH, subdivididos en fracción ácidos fúlvicos (N-FAF), ácidos húmicos (N-FAH) y humina (N-HUM). La conversión de áreas de SPC a SDH favorece el aumento de los niveles de NT y N-HUM en la capa de 0-5 cm. Entre las especies de plantas de cobertura utilizadas en el SDH, los cultivos asociados de avena + nabo favorecieron el aumento del N-HUM (0-20 cm) en comparación a los demás tratamientos. La avena solo y el control con vegetación espontánea aumentaron los niveles de N-FAH y N-FAF, respectivamente, en la capa de 10-20 cm, en comparación a los demás tratamientos en SDH y SPC. El SPC con mijo como planta de cobertura aumentó los niveles de N-FAF (0-20 cm) en comparación con el SDH.

ABSTRACT The objective of this study was to evaluate the soil total nitrogen (TN), and N contents in humic substances (HS) of the organic matter in aggregates of soils cultivated with onion under no-till system for horticulture (NTSH) and conventional tillage system (CTS), comparing with an area of forest. The evaluated treatments were natural vegetation (control), 100% black oats, 100% rye, 100% oilseed radish, intercrop of oilseed (14%) + rye (86%), intercrop of oilseed (14%) + black oats (86%), area under CTS of onion for ±37 years, and area with secondary forest for ±30 years. Five years after the NTSH implementation, undisturbed soil samples from the layers 0-5 cm, 5-10 cm, and 10-20 cm were collected; these samples presented aggregate sizes between 2.0 mm and 8.00 mm. The TN, and N contents of the HS were subdivided into fulvic acids (N-FA), humic acids (N-HA), and humin (N-HU) fractions. The change from CTS to NTSH increases the TN and N-HU contents in the 0-5 cm soil layer. The intercrop of oats and oilseed radish, used as soil plant cover species in NTSH, presented a greater increase in N-HU (0-20 cm) than the other treatments. Black oats, and natural vegetation presented a greater increased in N-HA, and N-FA contents, respectively, in the 10-20 cm layer, than the other treatments in NTSH and CTS. CTS with millet as soil plant cover presented a greater increase in N-FA (0-20 cm) contents than the NTSH treatments.

ABSTRACT Carbon (C) contents of humic substances (HS) in soil aggregates are a sensitive indicator of changes in the edaphic quality caused by soil management systems and/or cover plant species. The aim of this study was to assess total contents of C and HS of organic matter in soil aggregates cultivated with onion under a no-till vegetable production system (NTVS) and conventional tillage (CT) compared to a secondary forest area. Treatments consisted of single and mixed cover crops and onion under NTVS: spontaneous vegetation, 100% black oat; 100% rye; 100% oilseed radish; consortium of oilseed radish (14%) + rye (86%); consortium of oilseed radish (14%) + black oat (86%). An area cultivated with onion under CT (± 37 years) and a forest area (secondary forest; ± 30 years) were also evaluated. Five years after implementation of NTVS, undisturbed soil specimens were collected from the 0.0-0.05, 0.05-0.10 and 0.10-0.20 m layers and aggregates were obtained (8.00 mm > Ø > 2.0 mm). In tríese aggregates, total organic carbon (TOC) and C of HS were determined, subdividided into a fulvic acid fraction (C-FAF), humic acid fraction (C-HAF) and humin (C-HUM). With the C values of the HS the following ratios were calculated: C-HAF/C-FAF and (C-HAF+C-FAF)/C-HUM. The highest content of TOC, C-FAF, C-HAF and C-HUM were found in the forest. In NTVS, the contents of TOC (at the 0.0-0.05 m depth) and C-HUM (0.0-0.05 and 0.05-0.10 m) were higher than those found under CT. The highest C-FAF contents were found under CT. NTVS compared to CT favors the humification process (higher C-HUM content and lower ratios of C-HAF+C-FAF/C-HUM (at the 0.0-0.05 and 0.05-0.10 m depths) and the protection of organic matter (higher TOC contents at the 0.0-0.05 m depth)). A linear relationship was observed between C-HUM and N of HS. Among the cover plant species, rye alone and rye combined with oilseed radish had the best results regarding humification of organic matter with predominance of C-HUM and C-HAF. This pattern was also observed in the control for C-HUM, due to the abundance of plant families and species, indicating that plant biodiversification is an effective way to improve the quality of soil.

RESUMEN Los contenidos de carbono (C) de las sustancias húmicas (SH) en los agregados del suelo son un indicador sensible de los cambios en la calidad edáfica causados por los sistemas de manejo del suelo y / o las especies vegetales de cobertura. El objetivo de este estudio fue evaluar el contenido total de C y SH de materia orgánica en agregados de suelo cultivado con cebolla bajo sistema de siembra directa de hortalizas (SSDH) y sistema de preparación convencional (SPC), comparando con un área de bosque. Los tratamientos consistieron en cultivos de cobertura solos y asociados con cebolla bajo SSDH: vegetación espontánea, 100% avena negra; 100% centeno; 100% nabo forrajero; consorcio de nabo (14%) + centeno (86%); consorcio de nabo (14%) + avena negra (86%). También se evaluó un área cultivada con cebolla bajo SPC (± 37 años) y un área de bosque (bosque secundario, ± 30 años). Cinco años después de la implementación de SSDH, se escogieron muestras de suelo de las capas 0,0-0,05, 0,05-0.10 y 0,10-0,20 my obtenidos los agregados (8.00 > Ø > 2,0 mm). En estos agregados, se determinaron el carbono orgánico total (COT) y C de SH, subdivididos en fracción ácido fúlvico (C-FAF), fracción ácido húmico (C-FAH) y humin (C-HUM). Con los valores de C de las SH, se calcularon las siguientes proporciones: C-FAH/C- FAF y (C-FAH + C-FAF)/C- HUM. El mayor contenido de COT, C-FAF, C-FAH y C-HUM se obtuvo en el bosque. En SSDH, los contenidos de COT (0,0-0,05 m) y C-HUM (0,0-0,05 y 0,05-0,10 m) fueron más altos que aquellos encontrados bajo SPC. Los contenidos más altos de C-FAF se encontraron bajo SPC. En SSDH en comparación con SPC favorece el proceso de humificación (mayor contenido de C-HUM y menores índices de C-FAH + C-FAF/C- HUM (en las profundidades de 0.0-0.05 y 0,05-0,10 m) y la protección de la materia orgánica (mayor contenido de COT a 0,0-0,05 m de profundidad)). Entre las especies de plantas de cobertura, el centeno solo y centeno asociado con nabo tuvieron los mejores resultados en cuanto a la humificación de materia orgánica con predominio de C-HUM y C-FAH. Este patrón también se observó en el control para o C-HUM, debido a la abundancia de familias de plantas y especies, lo que indica que la biodiversidad de las plantas es una forma efectiva de mejorar la calidad del suelo.

ABSTRACT The purpose of this study was to evaluate Cu and Zn migration and fractions in sandy soil of vineyards. In Urussanga (SC), Brazil, soil samples were collected from a 4-year-old and 15-yearold vineyard, and from a forested area. In the soils, the chemical characteristics of Cu and Zn were analyzed by the EDTA method, which determines the fraction available in soil; 3050B method of the USEPA for total concentrations, which represents the pseudo-soil contents in the soil; and chemical fractionation, which estimates soluble fraction, exchangeable fraction, fraction associated with clay minerals, fraction associated with organic matter and residual fraction. The results show that there is accumulation of Cu and Zn in sandy soils cultivated with grapevines and with frequent fungicide applications. These higher levels were found in soils with longer cultivation time (15 years old), but were restricted to the superficial layers of the soil. Most of the Cu was extracted by EDTA method, and it may be considered as available to plants. The EDTA also extracted a small part of Zn. Most of the Cu in the vineyard soils can be characterized by low geochemical mobility, but in the uppermost soil layers of the oldest vineyard, there was an increase in Cu content associated with soil organic matter. Most of the Zn in the vineyard soil was associated with minerals, which indicates low mobility and also low potential for toxicity to plants and microorganisms.

RESUMO: Solos cultivados com videiras possuem alto teor de cobre (Cu) disponível, que pode ser tóxico às plantas de cobertura do solo que coabitam vinhedos, como a aveia preta. O estudo objetivou avaliar o efeito da calagem na redução da toxidez por Cu em plantas de aveia preta cultivadas em solo arenoso. Amostras de um Argissolo Vermelho foram coletadas na camada de 0-20cm, secas e submetidas à adição de duas doses de Cu (0 e 50Mg kg-1) e três de calcário (0, 1,5 e 3,0Mg ha-1). O solo foi acondicionado em rhizobox e submetido ao cultivo de aveia preta durante 30 dias. Avaliaram-se a produção de matéria seca das raízes e da parte aérea, o teor de cobre (Cu), cálcio (Ca) e magnésio (Mg) nos tecidos; o teor de Cu no simplasto e apoplasto das raízes, e os teores de Cu, de carbono e valores de pH no solo rizosférico e não rizosférico. A aplicação de calcário reduziu a toxidez por Cu na aveia preta. O Cu foi preferencialmente acumulado nas raízes, especialmente no apoplasto, o que pode ser resultado de mecanismo de tolerância das plantas para evitar o transporte de parte do elemento para a parte aérea.

ABSTRACT: Soils which are cultivated with grapevines have high available copper (Cu) content, which can be toxic to cover crops cohabiting vineyards, such as black oats. This study aimed to assess the effect of liming in reducing Cu toxicity in black oats grown in sandy soils. Samples of a Typic Hapludalf were collected at 0-20cm, dried and subjected to the addition of Cu (0 to 50Mg kg-1) and limestone (0, 1.5, and 3.0Mg ha-1). The soil was placed in a rhizobox and black oats were grown for 30 days. We assessed root and shoot dry matter production, copper (Cu), calcium (Ca) and magnesium (Mg) contents in the tissues; Cu content in the root symplast and apoplast, as well as Cu, carbon and pH values in the rhizosphere and bulk soil. Liming reduced Cu toxicity in black oats. Cu was preferentially accumulated in the roots, mostly in the apoplast, which may be the result of a plant tolerance mechanism to prevent the transport of Cu to the shoots.