Dynamics of Fe, Mn, and potentially harmful elements under reducing conditions in iron ore tailings after dam collapse in the Doce River basin-Brazil: flooded and non-flooded rice cultivations.

Potentially harmful element (PHE) bioavailability is important to environmental contamination and must be checked under several soil conditions. This study aimed to assess Fe, Mn, and PHE uptake by rice (Oryza sativa) grown on flooded and non-flooded Fe tailings collected from the Doce River basin after its collapse in Brazil. After 65 days of sowing, shoots and roots were harvested to determine PHE concentrations. The mean concentrations of Mn in shoots and Fe in the roots of rice grown on the flooded tailings were 2140 mg kg-1 and 15,219 mg kg-1, respectively. Mn was extensively translocated from roots to shoots (translocation factor (TF) = 2). Conversely, Fe accumulated in roots (TF = 0.015) and caused morphological damage to this rice organ. The application of macro and micronutrients lessened Fe toxicity in the roots of rice cultivated on the flooded tailings. The flooding of tailings influenced more Fe accumulation than Mn accumulation by rice plants. The PHE Ag, As, Cd, Ni, Hg, Pb, and Sb exhibited low total concentrations (maximum of 9 mg kg-1 for Ni and a minimum of 0.2 mg kg-1 for Cd, Hg, and Sb), and it was not observed an increase in their availability under tailings flooding conditions.

Doses and critical phosphorus level for yerba mate (Ilex paraguariensis St. Hil) clones / Doses e nível crítico de fósforo para erva-mate (Ilex paraguariensis St. Hil) clonal

In Brazil, the optimal dose of phosphorus in the cultivation of yerba mate (Ilex paraguariensis St. Hil.) clones has yet to be defined. This study verified the productivity of yerba mate clones in response to the application of P doses and determined the critical level of the nutrient in soil and yerba mate leaves. The experiment was developed in Itaiópolis-SC, in humic cambisol, from 2013 to 2020. Five doses of the nutrient were evaluated in two clones (BRS-BLD Aupaba and F2) of yerba mate. Fertility was defined by planting/post-planting (0, 2.3; 4.5; 6.8, and 9.0 g plant-1), canopy formation 1 (0, 10, 20, 30, 40, and 50 g plant-1), canopy formation 2 (0, 15, 30, 45, and 60 g plant-1), and production (0, 16.7; 33.3; 50.0; 66.7 kg ha-1). Harvests took place between July 2015 and January 2020, at 18-month intervals. The productivity of leaves, fine branches, and thick branches was evaluated. In the 2020 harvest, soil and leaf samples were collected to determine the critical level of P. The productivity of clone components increased with phosphate fertilization in all evaluated harvests. The critical levels of P for clones, Aupaba and F2, were 5.2 and 6.3 mg dm-3 in soil and 1.03 and 1.11 g kg-1 in leaves, respectively. Yerba mate is demanding of P, expressing maximum productivity in the planting phase, canopy formation 1 and 2, and production when doses of 5, 25, 40 g plant-1, and 35 kg ha-1 of P2O5 are applied, respectively.

No Brasil, a dose de fósforo no cultivo de clones de erva-mate ainda não está definida. O objetivo do estudo foi verificar a produtividade de clones de erva-mate em resposta a aplicação de doses de P e determinar o nível crítico do nutriente no solo e folhas de erva-mate. O experimento foi implantado em Itaiópolis-SC, em Cambissolo Húmico, em 2013. Foram avaliadas cinco doses do nutriente em dois clones (BRS-BLD Aupaba e F2) de erva-mate. As adubações foram definidas como de plantio/pós-plantio (0, 2,3; 4,5; 6,8 e 9,0 g planta-1), formação de copa 1 (0, 10, 20, 30, 40 e 50 g planta-1), formação de copa 2 (0, 15, 30, 45 e 60 g planta-1) e produção (0, 16,7; 33,3; 50,0; 66,7 kg ha-1). As colheitas ocorreram entre julho de 2015 e janeiro de 2020, com intervalos de 18 meses. Avaliou-se produtividade de folhas, galhos finos e galhos grossos. Na safra de 2020, foram coletadas amostras de solo e folhas para determinação do nível crítico de P. A produtividade dos componentes dos clones aumentou com a adubação fosfatada em todas as safras avaliadas. Os níveis críticos de P para os clones Aupaba e F2 foram 5,2 e 6,3 mg dm-3 no solo e 1,03 e 1,11 g kg-1 nas folhas, respectivamente. A erva-mate é exigente em P, expressando produtividade máxima na fase de plantio, formação de copa 1 e 2 e produção, quando aplicado doses de P2O5 em torno de 5, 25, 40 g planta-1 e 35 kg ha-1, respectivamente.

Accumulation Capacity of Nickel and Zinc in Yerba Mate Cultivated in Soils with Contrasting Parent Materials.

Yerba mate (Ilex paraguariensis St. Hill.) has shown a relatively high capacity for micronutrient absorption and could be a candidate for biofortification and combating a lack of micronutrients. To further evaluate the accumulation capacity of Ni and Zn, yerba mate clonal seedlings were grown in containers under five rates of Ni or Zn (0, 0.5, 2, 10, and 40 mg kg-1) with three soils originating from different parent material (basalt, rhyodacite, and sandstone). After 10 months, plants were harvested, divided into component parts (leaves, branches, and roots), and evaluated for 12 elements. The use of Zn and Ni enhanced seedling growth under rhyodacite- and sandstone-derived soils at the first application rate. Application of Zn and Ni resulted in linear increases based on Mehlich I extractions; recovery of Ni was smaller than Zn. Root Ni concentration increased from approximately 20 to 1000 mg kg-1 in rhyodacite-derived soil and from 20 to 400 mg kg-1 in basalt- and sandstone-derived soils; respective increases in leaf tissue were ~ 3 to 15 mg kg-1 and 3 to 10 mg kg-1. For Zn, the maximum obtained values were close to 2000, 1000, and 800 mg kg-1 for roots, leaves, and branches for rhyodacite-derived soils, respectively. Corresponding values for basalt- and sandstone-derived soils were 500, 400, and 300 mg kg-1, respectively. Although yerba mate is not a hyperaccumulator, this species has a relatively high capacity to accumulate Ni and Zn in young tissue with the highest accumulation occurring in roots. Yerba mate showed high potential to be used in biofortification programs for Zn.

Multi-elemental Analysis and Health Risk Assessment of Commercial Yerba Mate from Brazil.

Consumption of yerba mate occurs mostly in the form of hot infusion (chimarrão). Water solubility of elements found in commercialized yerba mate is needed to establish nutritional value and risks associated with potentially toxic elements. In this study, yerba mate products marketed in three Brazilian states (Paraná, Santa Catarina, and Rio Grande do Sul) for chimarrão were analyzed. Total (dry product) and hot water-soluble concentrations of Al, As, B, Ba, Ca, Cd, Co, Cs, Cu, Fe, K, Li, Mg, Mn, Mo, Ni, P, Pb, Rb, S, Se, Sr, Ti, V, and Zn were determined by inductively coupled plasma mass spectroscopy (ICP-MS). Total concentrations of the ten top elements followed the order of K>Ca>Mg>Mn>P>S>Al>Fe>Ba>Zn. The most soluble elements were B, Cs, Ni, Rb, and K, with values greater than 80%. The lowest water-soluble elements were V, Fe, and Ti (values <10%), followed by Ba, Cd, Al, As, Sr, Ca, and Pb with solubility between 10 and 20%. Although total Cd levels in yerba mate products were often above those permitted by South America legislation, estimated daily consumption intake indicated no risk associated with the chimarrão beverage. Manganese was the micronutrient with the highest total and soluble levels in yerba mate, which surpassed recommended daily intake values when considering a consumption amount of 50 g day-1 of yerba mate as chimarrão. The consumption of yerba mate is safe and contributes to intake of nutrients. The Cd and Pb reference values of yerba mate products sold in South America should be revised.

Elemental composition of yerba mate (Ilex paraguariensis A.St.-Hil.) under low input systems of southern Brazil.

Elemental composition of food can be used to determine nutritional potential as well as guiding legislation for establishing maximum acceptable limits (MAL) of metals in consumption products. This study aimed to determine the elemental background levels of yerba mate (Ilex paraguariensis A.St.-Hil.) under varied geologic formations in southern Brazil. Mature leaves were randomly collected from four wild-grown plants at thirty native sites in three states and analyzed for 32 elements. Since yerba mate is not washed to obtain the final product, leaves were analyzed with and without washing to assess foliar deposition. Concentration values of As, Ag, Be, Cs, Cr, Li, Se, Tl, U, and V were near detection limits, indicating low potential as a source and/or toxicity to the consumer. Washing decreased concentrations of Fe, Ti, As, Mo, Li, V, and Pb, suggesting atmospheric contributions/dust deposition. Concentrations of Mn (very high), Zn (high), and Ni (high) demonstrated that leaves could be an important source of these elements. Soil parent material affected elemental composition with basalt providing higher concentrations of Mn, P, and Co while Rhyodacite provided higher concentrations of K and Na. All samples exhibited Pb values below the MAL of 0.6 mg kg-1, but 23% of washed leaves and 20% of unwashed leaves had Cd concentrations close to or above the MAL value of 0.4 mg kg-1. Study results indicated that Cd MAL values for yerba mate in southern Brazil should be reassessed.

Minerals and potentially toxic elements in corn silage from tropical and subtropical Brazil

Our aim was to assess the mineral composition of corn silages produced in four states of Brazil: Goiás, Minas Gerais, Paraná, and Santa Catarina. In total, seventy-three samples were analyzed. Total element content was extracted by HNO3 and H2 O2 microwave-assisted digestion, and inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine concentration. Of the 31 elements analyzed (Ag, Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Se, Sr, Ti, Tl, U, V, and Zn), 21 had concentrations above equipment detection limits. No elements reached the maximum tolerable concentration, but concentrations of Ca (0.14-0.15%), Cu (3.4-5.6 mg kg−1), P (0.13-0.16%), S (0.06-0.08%), and Zn (13-19 mg kg−1) were below the adequate concentration for good nutritional balance. The strong and consistent correlation observed between Fe and Ti in silage samples indicated contamination by soil. Mean concentrations of Cu, Mn, Mo, P, S, and Zn were different among states, and canonic analyses successfully discriminate samples according to their state of origin. Minerals from corn silage should be considered when formulating balanced cattle diets. To ensure silage quality, farmers must adopt strategies that reduce contamination by soil during the ensiling process.(AU)

Environmental Soil Phosphorus Threshold under No-Tillage and Swine Manure Application

Abstract Swine manure is applied in agricultural fields as a source of nutrients for plant growth, however, excessive application over the years can promote soil phosphorus (P) accumulation. The objective of this study was to establish the environmental soil P threshold based on the degree of P saturation (DPS), as well, to evaluate the soil P storage capacity. The experiment was carried out in an Oxisol (sandy clay loam texture), under no-tillage and crop rotation. Treatments consisted of four annual doses of liquid swine manure (0, 100, 200, and 300 m3 ha-1 year-1), and three doses of mineral fertilizer (0, 50, and 100% of the crop nutrients requirement), in a randomized block with split-plot design (four replications). Soil P content was analyzed by PMehlich-1, PCaCl2, water-soluble P (WSP) and total P. The application of swine manure and mineral fertilizer increased soil P contents mainly at 0-10 cm depth. The DPS corresponding to the change point was 14.9% at depth 0-10 and 8.6% at depth 0-20 cm with WSP and 18.7% at 0-10 cm and 8.9% at 0-20 cm depth with PCaCl2. The lowest change point value was DPS 8.6% which corresponds to 43 mg kg-1 of PMehlich-1, so, in practical terms, we suggest this value as the environmental soil P threshold. The soil P storage capacity indicated negative values with the higher doses of swine manure and mineral fertilizer which increases the vulnerability of P loss by surface and subsurface hydrological transfer pathway.

Assessing soil contamination in automobile scrap yards by portable X-ray fluorescence spectrometry and magnetic susceptibility.

A by-product of industrialization and population growth, automobile scrap yards are a potential source of metal contamination in soil. This study evaluated the use of portable X-ray fluorescence (pXRF) spectrometry and magnetic susceptibility (χ) analysis in assessing metal soil contamination in scrap yards located in Brazil. Five automobile scrap yards were selected in Curitiba, Paraná State (CB1, CB2, and CB3) and Lavras, Minas Gerais State (LV1 and LV2). By evaluating metal concentrations and geoaccumulation index values, we verified moderate Cu, Pb, and Zr contamination and moderate to high Zn contamination, primarily in the topsoil (0-10 cm). Soil Zn concentrations in automobile scrap yards were on average four times higher than in reference soils, suggesting that galvanized automobile parts may be the primary source of this soil contaminant. Although other elements (i.e., As, Cr, Fe, Nb, Ni, and Y) were slightly increased compared to reference values in one or more soils, concentrations did not constitute contamination. Automobile scrap yard topsoil had higher χ values (5.8 to 52.9 × 10-7 m3 kg-1) at low frequency (χlf) compared to reference soil (3.6 to 7.5 × 10-7 m3 kg-1). The highest values of χlf occurred in LV soils, which also represented the highest Zn contamination. Magnetic multidomain characteristics (percent frequency-dependent susceptibility between 2 and 10) indicated magnetic particle contributions of anthropogenic origin. The use of pXRF and χlf as non-destructive techniques displays potential for identifying soil contamination in automobile scrap yards.

Elemental composition and nutritional value of Araucaria angustifolia seeds from subtropical Brazil.

Consumed by populations in South America, Araucaria angustifolia seeds have received little study regarding elemental composition and nutritional value. Thirty-five seed sites from subtropical Brazil were sampled and seed concentrations of C, N, K, Ca, Mg, P, Fe, Zn, Mn, Cu, Mo, Ni, Co, Cr, Ba, and Cd were determined. The highest concentration of N was observed in samples from regions with Cfa climate (humid subtropical, oceanic climate, without dry season with hot summer) and igneous rock, which was superior to regions with Cfb climate (humid subtropical, oceanic climate, without dry season with temperate summer) and metamorphic rock. Seeds can be a source of nutrients: K (11.8 g kg-1), P (4.1 g kg-1), Mn (9.1 mg kg-1), Cu (7.2 mg kg-1), Mo (0.93 mg kg-1), and Cr (0.65 mg kg-1). Values for Ba (0.93 mg kg-1) and Cd (0.19 mg kg-1) indicated no risk to human health. This study expands knowledge regarding the elemental composition of A. angustifolia. Results indicate that these seeds have nutritional value, and their consumption can be a good strategy to improve overall human nutrition in this region of South America.

Boron alters cation exchange properties of corn roots but does not decrease aluminum toxicity / Boro altera as propriedades de troca catiônica da raiz de milho, mas não diminui a toxidez por alumínio

Most studies that have registered amelioration of Al toxicity due to root cation exchange capacity (CEC) decrease with B application were conducted using eudicotyledonous species (high root CEC). However, the effect of B/Al interaction on the root CEC values in species with low root CEC such as corn (Zea mays L.) has been understudied. Thus, this study aimed to: (1) verify if B decreases root CEC and if it benefits the growth and nutrient uptake in corn plants under Al toxicity; and (2) verify which method of root CEC analysis better differentiates the effects of B and Al. Corn seedlings were grown in complete nutrient solution with the following treatments: 0, 50, and 200 µM of B versus 0 and 300 µM of Al. Root attributes showed correlations with nutrient depletion from the nutrient solution, but nutrient depletion generally varied with transpiration in two depletion tests. The addition of B or Al in nutrient solution decreased root CEC; however, B failed to decrease Al toxicity in corn plants. The four methods used to determine CEC of corn roots had contrasting results, particularly with respect to the effect of B in the presence of Al.

A maioria dos estudos que registraram amenização da toxidez de Al devido ao decréscimo da capacidade de troca de cátions (CTC) radicular com a aplicação de B foram realizados com espécies eudicotiledôneas (alta CTC radicular). Contudo, o efeito da interação B/Al nos valores de CTC radicular em espécies de baixa CTC radicular, como no milho (Zea mays L.), é pouco conhecido. Assim, os objetivos desse estudo foram: (1) verificar se o B reduz a CTC radicular e se isso beneficia o crescimento e a absorção de nutrientes em plantas de milho sob toxidez por Al; (2) verificar qual método para análise de CTC radicular diferencia melhor o efeito do B e Al. Plântulas de milho foram cultivadas em solução nutritiva completa com os seguintes tratamentos: 0, 50 e 200 µM de B versus 0 e 300 µM de Al. Os atributos radiculares apresentaram correlações com a depleção de nutrientes da solução nutritiva, mas, em geral, a depleção de nutrientes variou principalmente com a transpiração em dois testes de depleção. A adição de B na solução nutritiva reduziu a CTC radicular, o que também ocorreu quando o Al foi adicionado, contudo, o B não aliviou a toxidez por Al nas plantas de milho. Os quatro métodos usados para determinar a CTC radicular do milho tiveram resultados contrastantes, particularmente com relação ao efeito do B na presença de Al.

Alkalinized sewage sludge application improves fertility of acid soils / Aplicação de lodo de esgoto alcalinizado melhora a fertilidade de solos ácidos

ABSTRACT Although it is known that alkalinized sewage sludge raises the pH of acid soils, there is limited knowledge regarding its effects on other soil fertility indicators, such as P and K availability and soil organic C content. Thus, the goal of this study was to evaluate how the application of alkalinized sewage sludge affects the fertility of acid soil. Twenty sewage treatment plants were selected throughout Paraná State (Brazil), and samples of alkalinized sewage sludge and samples of the most representative agricultural soil of the region were collected (covering soils with medium, clayey or very clayey texture). Each soil was incubated for 60 days with doses of sewage sludge (0, 10, 20, 40, and 80 Mg ha-1) from its region and equivalent doses of limestone. The alkalinized sewage sludge was superior to limestone in the correction of soil acidity (pH, Al3+, and H + Al3+) and P and Ca2+ availability. The sludge also increased Mg2+ availability in all soils, K+ in seven soils and organic C in three soils. The very clayey soils (higher buffering capacity) supported higher sludge doses than did clayey and medium texture soils. The alkalinized sewage sludge application in acid soils proved to be an interesting alternative to recycling this type of waste, because it improved soil fertility and could reduce costs associated with soil management and crop fertilization.

RESUMO Embora seja conhecido a capacidade do lodo de esgoto alcalinizado em elevar o pH de solos ácidos, tem-se um limitado conhecimento sobre o efeito em outros indicadores da fertilidade do solo, como disponibilidade de P e K e, teor de C orgânico no solo. Assim, o objetivo do estudo foi avaliar como a aplicação de lodo de esgoto alcalinizado afeta a fertilidade de solos ácidos. Foram selecionadas vinte estações de tratamento de esgoto ao longo do Paraná (Brasil), onde foram coletadas amostras de lodo de esgoto alcalinizado e amostras do solo agrícola mais representativo da região (abrangendo solos com textura média, argilosa ou muito argilosa). Cada solo foi incubado por 60 dias com doses de lodo de esgoto (0, 10, 20, 40, e 80 Mg ha-1) da sua região e com doses equivalentes de calcário. O lodo de esgoto alcalinizado foi superior ao calcário na correção da acidez do solo (pH, Al3+ e H+Al3+) e na elevação da disponibilidade P e Ca2+. O lodo também aumentou a disponibilidade de Mg2+ em todos os solos, K+ em sete solos e C orgânico em três solos. Os solos muito argilosos (alta poder tampão) suportam maior dose de lodo em comparação aos solos de textura argilosa e média. A aplicação de lodo de esgoto alcalinizado em solos ácidos demonstrou ser uma interessante alternativa para reciclar esse tipo de resíduo, pois melhorou a fertilidade dos solos e pode vir a reduzir custos com manejo do solo e adubação das culturas.

Zinc, copper and manganese availability in soils treated with alkaline sewage sludge from Paraná state (Brazil) / Disponibilidade de Zn, Cu e Mn em solos tratados com lodo de esgoto alcalinizado do estado do Paraná (Brasil)

ABSTRACT In Paraná, most of the sludge generated in sewage treatment plants is subjected to the prolonged alkaline stabilization process. Although it is known that the alkaline sewage sludge contains micronutrients such as Zn, Cu and Mn, little is known about the availability of these elements in soils treated with this type of sewage sludge. Thus, the objective of the study was to evaluate the influence of alkaline sewage sludge from Paraná on Zn, Cu and Mn availability in soils. Twenty sewage treatment plants were selected throughout Paraná, where alkaline sewage sludge and the most representative agricultural soil of the each region were collected. Each soil was incubated for 60 days with alkaline sewage sludge rates (0, 10, 20, 40, and 80 Mg ha-1) from their region. Subsequently, Zn, Cu and Mn availability was determined using the Mehlich-1 extractant. The alkaline sewage sludge increased Zn availability and decreased Mn availability in most soils. Cu showed intermediate results, with increased availability, primarily in medium texture soils and decrease in most of the clayey soils. In soils with pH close to ideal for the plant growth, the alkaline sewage sludge rate should be carefully calculated so that there is no excessive increase in the pH and Zn, Cu and Mn imbalance.

RESUMO No Paraná, a maioria do lodo de esgoto gerado em estações de tratamento é submetida ao processo de estabilização alcalina prolongada. Embora seja conhecido que o lodo de esgoto alcalinizado contém micronutrientes como Zn, Cu e Mn, pouco se conhece sobre a disponibilidade desses elementos em solos tratados com esse tipo de lodo de esgoto. Assim, o objetivo do estudo foi avaliar a influência de lodos de esgoto alcalinizados do estado do Paraná sobre a disponibilidade de Zn, Cu e Mn no solo. Foram selecionadas vinte estações de tratamento de esgoto ao longo do Paraná, onde foram coletadas amostras de lodo de esgoto alcalinizado e amostras do solo agrícola mais representativo da região. Cada solo foi incubado por 60 dias com doses de lodo de esgoto (0, 10, 20, 40, e 80 Mg ha-1) da sua região. Posteriormente, foi determinada a disponibilidade de Zn, Cu e Mn no solo usando o extrator Mehlich-1. A aplicação de lodo de esgoto alcalinizado ao solo aumentou a disponibilidade de Zn e diminuiu a disponibilidade de Mn na maioria dos solos. Já o Cu apresentou resultados intermediários, com aumento de disponibilidade basicamente em solos de textura média e com diminuição para a maioria dos solos muito argilosos. Em solos com pH próximo ao ideal para o cultivo agrícola, a dose de lodo de esgoto alcalinizado deve ser cuidadosamente calculada para que não ocorra o aumento excessivo do pH e desbalanço nos teores de Zn, Cu e Mn.

Influence of zinc deficiency on the mineral composition of maize plants in contrasting soils / Influência da deficiência de zinco na composição mineral de plantas de milho em solos contrastantes

In Brazil, Zn deficiency is common in soils used for maize cultivation. However, the changes in the mineral composition in plants with Zn deficiency have been little studied. Thus, this study aimed to evaluate the relationship between Zn deficiency and the mineral composition in the parts of maize plants grown under contrasting soils. Maize was grown in greenhouse conditions with increasing of Zn rate (0, 0.125, 0.25, 0.5 and 1.0 mg kg-1) in two soils (Ferralsol and Cambisol). After 60 days of emergence, the plant were separated into roots, stalk nodes, stalk internodes, leaves and leaf sheath, and subsequently determined the dry matter and mineral composition (P, Ca, Mg, K, Zn, Fe, Mn, Cu and Al). Besides the symptoms commonly described for Zn deficiency, darkening of the stalk nodes was found (related to the preferential accumulation of Fe), and also occurred maize P deficiency in the Ferralsol. The Zn deficiency favored increasing concentrations of Fe, Mn and Al in all parts of maize plants in Cambisol, whereas in Ferralsol this did not happen for any of the elements analyzed. Relations between the elements and Zn were more correlated with maize dry matter production than Zn concentrations in leaves, leaf sheaths and stalk nodes. In conclusion, the accumulation of minerals in maize was favored by Zn deficiency, especially for maize in Cambisol.

No Brasil, a deficiência de Zn é comum em solos utilizados para o cultivo do milho. Contudo, as mudanças na composição mineral das plantas resultantes da deficiência de Zn têm sido pouco estudadas. Assim, esse estudo objetiva avaliar a relação entre a deficiência de Zn e a composição mineral nas partes de plantas de milho cultivadas em solos contrastantes. O milho foi cultivado em casa de vegetação com doses crescentes de Zn (0; 0,125; 0,25; 0,5 e 1,0 mg kg-1) em dois solos (Latossolo e Cambissolo). Após 60 dias da emergência, as plantas foram fracionadas em raízes, nós do colmo, entrenós do colmo, folhas e bainha das folhas, sendo, posteriormente, determinadas a matéria seca e a composição mineral (P, Ca, Mg, K, Zn, Fe, Mn, Cu e Al). Além dos sintomas comumente descritos para deficiência de Zn, constatou-se escurecimento dos nós do colmo (relacionado ao acúmulo preferencial de Fe), sendo que no Latossolo também ocorreu deficiência de P. A deficiência de Zn favoreceu o aumento das concentrações de Fe, Mn e Al em todas as partes das plantas de milho no Cambissolo, enquanto que no Latossolo isso não ocorreu para nenhum dos elementos analisados. As relações entre os elementos e o Zn foram mais correlacionadas com a produção de matéria seca do milho que as concentrações de Zn em folhas, bainhas das folhas e nós do colmo. Pode-se inferir que a acumulação de minerais no milho foi favorecida pela deficiência de Zn, principalmente no Cambissolo.

Dinâmica de crescimento e produtividade de forragem de Trachypogonplumosus sob níveis de correção da fertilidade do solo e idades de rebrota / Growth dynamic and forage yield of Trachypogon plumosus under levels of soil fertility correction and regrowth ages

Avaliaram-se os efeitos de níveis de correção da fertilidade do solo (testemunha, calagem, adubação e calagem + adubação) e da idade de rebrota (21, 28, 35, 42, 49, 56, 63, 70, 77 e 84 dias) sobre a dinâmica de crescimento e rendimento de forragem de Trachypogon plumosus em Roraima. O aumento da idade de rebrota resultou em maiores rendimentos de matéria seca (MS), taxa absoluta de crescimento (TAC), taxa de assimilação líquida (TAL), razão de área foliar (RAF) e índice de área foliar (IAF), ocorrendo o inverso quanto à taxa média de crescimento (TMC). A gramínea mostrou-se responsiva à melhoria da fertilidade do solo. A calagem + adubação ou a adubação proporcionaram maiores rendimentos de MS (1.934 e 1.661 kg ha-1), TAC (36,6 e 31,5 kg ha-1 dia-1), TMC (32,5 e 27,9 kg ha-1 dia-1), TAL (4,993 e 4,152 g/m2), RAF (152,9 e 140,9 cm2/g) e IAF (2,42 e 2,14). Para otimizar a eficiência de utilização da forragem produzida e reduzir perdas por senescência da gramínea, o período mais adequado de sua utilização, durante o período chuvoso, situa-se entre 56 e 63 dias com o uso de adubação e calagem + adubação e entre 63 a 70 dias para a testemunha e a calagem(AU)

We assessed the effects of levels of soil fertility correction (control, liming, fertilization and liming + fertilization) and of regrowth ages (21, 28, 35, 42, 49, 56, 63, 70, 77, and 84 days) on growth dynamic and forage yield of Trachypogon plumosus in the Roraima´s savannas. Dry matter (DM) yields, absolute growth rate (AGR), net assimilation rate (NAR), and leaf area ratio (LAR) increased consistently with regrowth age, while the crop growth rate (CGR) was inversely proportional to regrowth age. The grass showed high responsivity to soil fertility improvement. Liming + fertilization or fertilization alone provided higher DM yields (1,934 and 1,661 kg ha-1), AGR (36.6 and 31.5 kg ha-1.day), CGR (32.5 and 27.9 kg ha-1.day), NAR (4.993 e 4.152 g/m2), LAR (152.9 and 140.9 cm2/g), and LAI (2.42 and 2.14). Regrowth intervals of 56 to 63 days for liming + fertilized and fertilized pastures, and 63 to 70 days for control or liming pastures were appropriate to provide maximum forage yields, growth rates and to prevent larger losses relative to senescence and leaf death(AU)

Dinâmica de crescimento e produtividade de forragem de Trachypogonplumosus sob níveis de correção da fertilidade do solo e idades de rebrota / Growth dynamic and forage yield of Trachypogon plumosus under levels of soil fertility correction and regrowth ages

Avaliaram-se os efeitos de níveis de correção da fertilidade do solo (testemunha, calagem, adubação e calagem + adubação) e da idade de rebrota (21, 28, 35, 42, 49, 56, 63, 70, 77 e 84 dias) sobre a dinâmica de crescimento e rendimento de forragem de Trachypogon plumosus em Roraima. O aumento da idade de rebrota resultou em maiores rendimentos de matéria seca (MS), taxa absoluta de crescimento (TAC), taxa de assimilação líquida (TAL), razão de área foliar (RAF) e índice de área foliar (IAF), ocorrendo o inverso quanto à taxa média de crescimento (TMC). A gramínea mostrou-se responsiva à melhoria da fertilidade do solo. A calagem + adubação ou a adubação proporcionaram maiores rendimentos de MS (1.934 e 1.661 kg ha-1), TAC (36,6 e 31,5 kg ha-1 dia-1), TMC (32,5 e 27,9 kg ha-1 dia-1), TAL (4,993 e 4,152 g/m2), RAF (152,9 e 140,9 cm2/g) e IAF (2,42 e 2,14). Para otimizar a eficiência de utilização da forragem produzida e reduzir perdas por senescência da gramínea, o período mais adequado de sua utilização, durante o período chuvoso, situa-se entre 56 e 63 dias com o uso de adubação e calagem + adubação e entre 63 a 70 dias para a testemunha e a calagem

We assessed the effects of levels of soil fertility correction (control, liming, fertilization and liming + fertilization) and of regrowth ages (21, 28, 35, 42, 49, 56, 63, 70, 77, and 84 days) on growth dynamic and forage yield of Trachypogon plumosus in the Roraima´s savannas. Dry matter (DM) yields, absolute growth rate (AGR), net assimilation rate (NAR), and leaf area ratio (LAR) increased consistently with regrowth age, while the crop growth rate (CGR) was inversely proportional to regrowth age. The grass showed high responsivity to soil fertility improvement. Liming + fertilization or fertilization alone provided higher DM yields (1,934 and 1,661 kg ha-1), AGR (36.6 and 31.5 kg ha-1.day), CGR (32.5 and 27.9 kg ha-1.day), NAR (4.993 e 4.152 g/m2), LAR (152.9 and 140.9 cm2/g), and LAI (2.42 and 2.14). Regrowth intervals of 56 to 63 days for liming + fertilized and fertilized pastures, and 63 to 70 days for control or liming pastures were appropriate to provide maximum forage yields, growth rates and to prevent larger losses relative to senescence and leaf death

DINÂMICA DE CRESCIMENTO E PRODUTIVIDADE DE FORRAGEM DE Trachypogonplumosus SOB NÍVEIS DE CORREÇÃO DA FERTILIDADE DO SOLO E IDADES DE REBROTA

Abstract We assessed the effects of levels of soil fertility correction (control, liming, fertilization and liming + fertilization) and of regrowth ages (21, 28, 35, 42, 49, 56, 63, 70, 77, and 84 days) on growth dynamic and forage yield of Trachypogon plumosus in the Roraima´s savannas. Dry matter (DM) yields, absolute growth rate (AGR), net assimilation rate (NAR), and leaf area ratio (LAR) increased consistently with regrowth age, while the crop growth rate (CGR) was inversely proportional to regrowth age. The grass showed high responsivity to soil fertility improvement. Liming + fertilization or fertilization alone provided higher DM yields (1,934 and 1,661 kg ha-1), AGR (36.6 and 31.5 kg ha-1.day), CGR (32.5 and 27.9 kg ha-1.day), NAR (4.993 e 4.152 g/m2), LAR (152.9 and 140.9 cm2/g), and LAI (2.42 and 2.14). Regrowth intervals of 56 to 63 days for liming + fertilized and fertilized pastures, and 63 to 70 days for control or liming pastures were appropriate to provide maximum forage yields, growth rates and to prevent larger losses relative to senescence and leaf death.

Resumo Avaliaram-se os efeitos de níveis de correção da fertilidade do solo (testemunha, calagem, adubação e calagem + adubação) e da idade de rebrota (21, 28, 35, 42, 49, 56, 63, 70, 77 e 84 dias) sobre a dinâmica de crescimento e rendimento de forragem de Trachypogon plumosus em Roraima. O aumento da idade de rebrota resultou em maiores rendimentos de matéria seca (MS), taxa absoluta de crescimento (TAC), taxa de assimilação líquida (TAL), razão de área foliar (RAF) e índice de área foliar (IAF), ocorrendo o inverso quanto à taxa média de crescimento (TMC). A gramínea mostrou-se responsiva à melhoria da fertilidade do solo. A calagem + adubação ou a adubação proporcionaram maiores rendimentos de MS (1.934 e 1.661 kg ha-1), TAC (36,6 e 31,5 kg ha-1 dia-1), TMC (32,5 e 27,9 kg ha-1 dia-1), TAL (4,993 e 4,152 g/m2), RAF (152,9 e 140,9 cm2/g) e IAF (2,42 e 2,14). Para otimizar a eficiência de utilização da forragem produzida e reduzir perdas por senescência da gramínea, o período mais adequado de sua utilização, durante o período chuvoso, situa-se entre 56 e 63 dias com o uso de adubação e calagem + adubação e entre 63 a 70 dias para a testemunha e a calagem.

Acúmulo de forragem e morfogênese de Trachypogon plumosus sob diferentes níveis de adubação nitrogenada / Forage accumulation and morphogenesis of Trachypogon plumosus under different levels of nitrogen fertilization

O efeito da adubação nitrogenada (0, 50, 100 e 200 kg N ha-1) sobre o acúmulo de forragem e características morfogênicas e estruturais de Trachypogon plumosus foi avaliado nos cerrados de Roraima. O delineamento experimental foi em blocos casualizados com três repetições. A adubação nitrogenada proporcionou incrementos quadráticos na produção de matéria seca, teores de nitrogênio, taxas de aparecimento e alongamento foliar, número de folhas vivas/perfilho, comprimento final de folha e índice de área foliar, sendo os máximos valores estimados com a aplicação de 153,5 (2.849 kg ha-1); 124,0 (23,97 g/kg); 155,4 (0,155 folha perfilho-1 dia-1); 116,1 (2,64 cm dia-1 perfilho-1); 147,0 (6,43 folhas perfilho-1), 135,1 (19,04 cm) e 181,2 kg de N ha-1 (2,56), respectivamente. A densidade populacional de perfilhos e a taxa de senescência foliar foram diretamente proporcionais às doses de nitrogênio, ocorrendo o oposto quanto à eficiência de utilização e a recuperação aparente do nitrogênio.

The effect of nitrogen fertilization (0, 50, 100 and 200 kg N ha-1) on forage production and morphogenetic and structural characteristics of Trachypogon plumosus was evaluated in the Roraima´s savannas. The experimental design was in randomized blocks with three replicates. Nitrogen fertilization promoted quadratic increase in the dry matter (DM) yield, nitrogen contents, leaf appearance rate, leaf elongation rate, number of live leaves/tiller, final leaf length and leaf area index; maximum values were estimated with application of 153.5 (2,849 kg ha-1); 124.0 (23.97 g/kg); 155.4 (0.155 leaf tiller-1 day-1); 116.1 (2.64 cm day-1 tiller-1); 147.0 (6.43 leaves tiller-1); 135.1 (19.04 cm) and 181.2 kg N ha-1, (2.56), respectively. Tiller population density and leaf senescence rate were directly proportional to nitrogen levels, and the opposite occurred for efficiency of utilization and apparent nitrogen recovery.

Produtividade de forragem e composição química de Trachypogon plumosus sob níveis de correção da fertilidade do solo e desfolhação / Forage production and chemical composition of Trachypogon plumosus under soil fertility correction and defoliation levels

Foram avaliados os efeitos de níveis de correção da fertilidade do solo (testemunha, calagem, adubação e calagem + adubação), níveis de desfolhação (remoção de 50 e 75% da parte aérea da gramínea) e estações de crescimento (períodos chuvoso e seco) sobre a produtividade e composição química da forragem de Trachypogon plumosus nos cerrados de Roraima. A gramínea apresentou alta responsividade à melhoria do ambiente de produção, apesar de sua boa adaptação aos solos de baixa fertilidade de cerrados. O aumento da intensidade de desfolhação, durante o período chuvoso, reduziu as taxas de crescimento e a produtividade e qualidade da forragem, independentemente do nível de correção da fertilidade do solo, não sendo detectado efeito significativo (P>0,05) durante o período seco. Os maiores rendimentos de matéria seca verde (P<0,05) foram registrados durante o período chuvoso, com 50% de desfolhação e utilização da calagem + adubação (6.607 kg ha-1) ou adubação (6.314 kg ha-1). A remoção de 75% do dossel da pastagem em combinação com a calagem + adubação (2.433 kg ha-1) ou adubação (2.335 kg ha-1), durante o período chuvoso, resultou em maior acúmulo de material morto. Os maiores teores de nitrogênio (N) e os menores de fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA) foram estimados durante o período chuvoso e com a utilização de calagem + adubação (16,22 g kg-1 de N; 71,89% de FDN e 34,11% de FDA) ou adubação (15,79 g kg-1 de N, 72,14% de FDN e 35,83% de FDA). A utilização da adubação ou calagem + adubação e do nível de desfolhação de 50% asseguram melhor distribuição estacional e maior produtividade e qualidade da forragem, além da redução no intervalo entre pastejos.

To evaluate the effects of soil fertility correction levels (control, liming, fertilization and liming + fertilization), defoliation levels (removal of 50 or 75% of pasture canopy) and growing season (rainy and dry season) on forage production and chemical composition of Trachypogon plumosus in Roraima´s savannas. The grass showed responsivity to the improvement of the production environment, despite its good adaptation to soils of low fertility of savannas. The increased grazing intensity, during the rainy season, reduced growth rates and forage productivity and quality, irrespectively to soil fertility correction levels, while was not detected significative effect (P>0.05) during dry season. The highest yields of green dry matter (P<0.05) were recorded during the rainy season, with 50% defoliation and use of lime + fertilizer (6,607 kg ha-1) or fertilization (6,314 kg ha-1). The removal of 75% of pasture canopy in combination with lime + fertilizer (2,433 kg ha-1) or fertilization (2,335 kg ha-1), during the rainy season resulted in higher accumulation of dead material. The highest levels of nitrogen (N) and the lowest neutral detergent fiber (NDF) and acid detergent fiber (ADF) were estimated during the rainy season jointly with lime + fertilizer (16.22 g kg-1 of N; 71.89% of NDF and 34.11% of ADF) or fertilization (15.79 g kg-1 of N; 72.14% of NDF and 35.83% of ADF). The use of fertilizer and lime + fertilizer and defoliation level of 50% provided better seasonal distribution and higher productivity and quality of forage, besides the reduction in grazing interval.

Lodos de esgoto alcalinizados em solos do estado do Paraná: taxa de aplicação máxima anual e comparação entre métodos para recomendação agrícola / Alkaline sewage sludge on soils of Paraná state: maximum annual application rate and comparison between methods for agricultural recommendation

Para o uso agrícola do lodo de esgoto higienizado por processo de estabilização alcalina prolongada (lodo EAP), além de estabelecer limites de aplicação máxima conforme a legislação, é necessário estudar atributos dos lodos e dos solos que favoreçam as metodologias de sua recomendação. Objetivou-se determinar a taxa de aplicação máxima anual (TAMA) de lodo EAP pelo critério de elevação do pH para 20 lodos e solos do estado do Paraná; determinar a influência dos atributos desses solos nos valores da TAMA de lodo EAP; avaliar o uso dos métodos de saturação por bases (V%) e pH referência (SMP), utilizando como padrão o método da incubação. Empregou-se o ensaio de incubação para lodo EAP aplicado ao solo, conforme metodologia oficial. Os resultados indicam que as TAMA de lodo EAP variaram de 10 a >80 Mg.ha-1 para as 20 regionais estudadas; Os atributos químicos (capacidade de troca de cátions, H+Al e carbono) e físico (argila) são os que melhor definem a determinação da TAMA, apresentando relação diretamente proporcional. Os métodos do V% e do pH referência (SMP) para pH H2O 5,5 mostraram-se seguros quanto à recomendação agrícola.

For agricultural use of alkalinized sludge (AS), beyond to establish the maximum application limits to comply with the legislation, it is necessary to study the attributes of sludges and soils that favor the methodologies of its recommendation. The objectives of this study were to determine the maximum annual application rate (MAAR) of alkalinized sludge (AS) according to the pH elevation criterion for 20 sludge origins and soils of the Paraná state; to determine the influence of soil attributes over the MAAR of AS; to evaluate two methods rate calculation for AS, the base saturation (V%) and pH reference (SMP) by comparing with the standard incubation methodology for AS sludge application. It was used incubation test for AS applied to soil, following official methodology. The results indicated that the MAAR were ranged 10 to >80 Mg.ha-1, for the 20 regions; the chemical properties (cation exchange capacity, H+Al and carbon) and physical properties (clay) were the best parameters to the determination of the MAAR, showing direct relationship; the V% and SMP (pH H2O 5,5) methods were safe to the agricultural recommendation.

Mineralogia e reserva de K de Cambissolos submetidos a diferentes manejos após derrubada e queima da floresta na Amazônia Meridional / Mineralogy and K reserve of Cambisols submitted to different managements after slashing and burning of the forest in the Meridional Amazon, Brazil

As altas temperaturas ocorrentes durante a queima na floresta Amazônica podem induzir transformações mineralógicas da fração argila. Este trabalho objetivou avaliar as alterações mineralógicas nas frações areia, silte e argila e na reserva mineral de solos submetidos a diferentes manejos (11 anos de mata secundária, pastagem e café) após a derrubada e queima de floresta nativa situada na Amazônia Meridional, município de Cacoal (RO). Uma área de floresta nativa ombrófila densa, com mesma feição pedológica, foi dividida em quatro partes, sendo três áreas submetidas ao corte e à queima e posteriormente cultivadas. Em cada manejo, os perfis de solos foram descritos e amostras dos horizontes A, AB, B1, 2B2 e 2BC foram coletadas para as análises mineralógicas das frações argila, silte e areia (difratometria de raios X) e químicas da fração argila (extração de Fe com ditionito-citrato-bicarbonato - DCB e com oxalato de amônio - OA). Os teores de K não trocáveis foram determinados nas amostras de solo após extração com HNO3 1 mol L-1 fervente. Verificou-se o predomínio da caulinita na fração argila e alta reserva mineral de K nos solos, associada à ocorrência de mica nas frações argila, silte e areia. Os diferentes manejos não afetaram os teores de Fe2 O3 DCB e Fe2 O3 OA; por outro lado, o maior valor estimado para a relação entre os teores de goethita e hematita [Gt/(Gt+Hm)] na fração argila no horizonte A da floresta indica uma possível transformação parcial de Gt em Hm durante a queima da floresta para a implantação dos manejos mata secundária, pastagem e café.

The high soil temperatures that take place during the burning of the Amazon rainforest may induce soil mineralogical transformations. This study aimed to evaluate mineralogical changes in sand, silt and clay fractions and to assess K reserve of soils submitted to different managements (11 years of secondary forest, pasture and coffee plantation) after slashing and burning of a native forest in the Southern Amazon, Cacoal, Rondônia State, Brazil. An area of ombrophilous dense native forest with homogeneous pedologic features was divided into four parts, being three of them submitted to slash and burn and then cropped. In each area, soil profile was described and the A, AB, B1, 2B2 and 2BC horizons were sampled. Mineralogical analyses of clay, silt and sand fractions were performed by X ray diffraction. Clay fraction was also submitted to selective solvent with citrate-bicarbonate-dithionite (CBD) and ammonium oxalate (AO). The soil contents of non-exchangeable K was extracted by boiling with 1 mol L-1 HNO3 . Soil mineralogical analysis indicated that kaolinite was the predominant mineral in the clay fraction. There was also evidence of a large reserve K, associated to the occurrence of mica in clay, silt and sand fractions. Chemical analysis indicated that land use did not change the concentration of Fe2 O3 CBD and Fe2 O3 AO. However, the highest goethite/hematite ratio [Gt(Gt+Hm)] calculated for the A horizon of the forest soil suggests that the burning favored the partial transformation of goethite in hematite into those areas where it was carried out.