Resumo -O objetivo deste trabalho foi avaliar os efeitos da compactação do solo sobre suas propriedades morfoestruturais e sobre o desenvolvimento radicular da soja, sob sistema plantio direto, em um experimento conduzido num Latossolo Vermelho distroférrico, em Londrina, PR. O delineamento utilizado foi o de blocos ao acaso, com parcelas subdivididas e quatro repetições. Foram constituídos dois tratamentos de manejo nas parcelas: um em solo escarificado à profundidade de 20-25 cm, com densidade do solo de 1,17 Mg m -3 ; e outro em solo compactado, a 12 cm de profundidade, e densidade de 1,38 Mg m -3 . Nas subparcelas, foram semeadas duas cultivares de soja, Embrapa-4 e BR-16. A presença de camadas mais compactas no perfil do solo provocou o desenvolvimento radicular em zonas de menor resistência, em poros biológicos e nas fissuras do solo. A produção de grãos não apresentou diferença entre os tratamentos, graças à adequada disponibilidade hídrica durante o período avaliado. A cultivar Embrapa-4 apresentou maior crescimento radicular em estruturas compactas, comparada à cultivar BR-16.Termos para indexação: caracterização morfoestrutural do solo, distribuição de raízes, resistência do solo à penetração. Soybean root system in function of soil compaction under no-tillage systemAbstract -An experiment was carried out on a Rhodic Ferralsol, in Londrina, PR, to evaluate the soil compaction effects on soil morphostructure and on soybean root distribution, under no-tillage system. The field experiment was arranged in a completely randomized block (split plot) design with four replicates, and with the compacted treatments in the main plots and soybean varieties in subplots. The treatments were: one scarified soil until 20-25 cm depth layer with bulk density of 1.17 Mg m -3 , and one compacted soil with bulk density of 1.38 Mg m -3 , in a 12 cm depth. Two varieties of soybean, Embrapa-4 and BR-16, were cultivated on subplots. Roots developed in zones with less resistance of penetration and in biological tunnels. The soybean grain yield was not different under compacted and noncompacted soil, because soil water moisture was adequate. Embrapa-4 showed greater root density than BR-16.

Although anthropogenic dark earth (ADE) is generally found in non-floodable land, it also occurs on floodplains but, there is no information about the chemical and physical characteristics of ADE in this environment. In this study, we propose to check the hypothesis that a Gleysol, classified as ADE, presents improved chemical and physical conditions than an adjacent soil, no anthropogenic. Thus, the objective of this study was to characterize the chemical and physical properties of the top layer of two ADE profiles in a Gleysol and compare them with an adjacent soil. Samples were taken from two areas classified as ADE in Bragança, Pará State, Brazil, at the "Jabuti" archaeological site, and from an adjacent non-anthropogenic site. Disturbed and undisturbed soil samples were collected at the soil depth of 0.05-0.10 m for chemical (pH, potential acidity, exchangeable cations, and soil organic carbon) and physical (soil particle size distribution, particles density, water retention curve, total porosity, microporosity, macroporosity, and bulk density) analysis. The two areas of ADE in a Gleysol, showed improved soil chemical properties compared to the adjacent soil, particularly in relation to phosphorus and calcium levels that contributed to higher cation exchange capacity which, in turn, was positively related to organic carbon content. Changes in soil physical properties were less noticeable but both areas of ADE presented higher water retention capacity, particularly at low tension. The improved conditions of the ADE soil under Gleysols shows that these areas are adequate for soil cultivation, especially with plants adapted to floodplain.KEYWORDS: Anthropic horizon, Soil organic carbon, Soil quality, Floodplain soils Propriedades físicas e químicas de Terra Preta Antropogênica em Bragança, Pará, Amazônia Oriental RESUMOEmbora as terras pretas antropogênicas (TPA) geralmente são encontradas em áreas de terra firme, elas também ocorrem em áreas e várzeas, mas, não há informações sobre as características químicas e físicas de TPA neste ambiente. Neste estudo, nós propomos verificar a hipótese de que um Gleissolo, classificado como TPA, apresenta melhores condições químicas e físicas do que o solo adjacente, não antropogênico. Assim, o objetivo do estudo foi caracterizar as propriedades químicas e físicas da camada superficial de dois perfis de TPA em um Gleissolo e compará-los com um solo adjacente. Amostras de solo foram coletadas em duas áreas classificadas como TPA em Bragança, Estado do Pará, Brasil, no sítio arqueológico "Jabuti" e em uma área adjacente não antropogênica. Amostras de solo com estrutura deformada e indeformada foram coletadas na profundidade de 0,05-0,10 m para análises químicas (pH, acidez potencial, cátions trocáveis, e carbono orgânico do solo) e físicas (distribuição do tamanho das partículas do solo, densidade de partículas, curva de retenção de água, porosidade total, microporosidade, macroporosidade e densidade do solo). As duas áreas de TPA em Gleissolo, apresentaram melhores ...

Resumo -O objetivo deste trabalho foi calibrar o medidor de clorofila Minolta SPAD-502 para avaliação da nutrição nitrogenada das plantas de milho, baseando-se na prévia comparação das leituras de clorofila com os teores obtidos pelos extratores N,N-dimetilformamida (DMF) e acetona 80%. No campo, foram avaliados os teores de clorofila em folhas de milho cultivado sob plantio direto após a cultura de aveiapreta e após a de tremoço-branco, por duas safras consecutivas. A extração da clorofila com a solução DMF, por 72 horas, foi a mais indicada para a calibração do medidor de clorofila SPAD-502 na cultura do milho. O ajuste do modelo linear expressou melhor a relação entre o conteúdo de clorofila e as leituras do SPAD na cultura do milho, e seu uso produziu resultados coerentes com o estado nutricional da cultura.Termos para indexação: Avena strigosa, Lupinus albus, adubo verde, estado nutricional. Calibration of a Minolta SPAD-502 chlorophyll meter for evaluation of the nitrogen nutrition of maizeAbstract -The subject of this study was the calibration of a Minolta SPAD-502 chlorophyll meter for evaluation of the N nutrition of maize, firstly comparing the chlorophyll readings to the contents obtained from either 80% acetone or N,N-dimethylformamide (DMF) chlorophyll extrators. The chlorophyll of the maize leaves cultivated under zero-tillage after oat and lupin for two consecutive harvests was evaluated in a field experiment. The chlorophyll extraction after 72 hours in DMF solution, was the most suitable for the calibration of the SPAD-502 chlorophyll meter for maize and its use was coherent with the nutritional status of the crop.

RESUMOObjetivou-se avaliar alguns componentes químicos de um Latossolo e a relação com o desenvolvimento vegetativo do paricá [Schizolobium amazonicum (Huber ex Ducke)] em diferentes sistemas de cultivo em áreas de reflorestamento no município de Tailândia, nordeste paraense. Foram avaliados os sistemas PP [paricá x puerária (Pueraria phaseoloides)], PA [paricá x acácia (Acacia mangium)] e P (paricá monocultivo) conduzidos em 5 anos pela empresa G.M. Sufredini Industrial Ltda. e coletadas amostras de solos na profundidade de 0-20 cm para análise de pH, C e N totais, H+Al, P disponível, Ca, Mg, K e Al trocáveis e calculados os valores de C/N, SB, T, V e m. O desenvolvimento vegetativo do paricá foi avaliado pela sobrevivência, mortalidade e no número de plantas defeituosas além do DAP. Os resultados mostraram que houve o aumento no teor de nitrogênio do solo no tratamento PP; a baixa fertilidade do solo no tratamento PA, mas onde o paricá obteve a maior média em diâmetro (DAP = 16,64 cm) e a maior taxa de sobrevivência no tratamento P (90,63%). Conclui-se que a relação solo-planta nos sistemas paricá e puerária e paricá em monocultivo contribuiu para o estabelecimento dos indivíduos de paricá. Palavras-chave: silvicultura; DAP; fertilidade do solo. ABSTRACTThis study aimed to evaluate some chemical components of an Oxisol and the relationship with the vegetative development of paricá [Schizolobium amazonicum (Huber ex Ducke)] in different cropping systems in reforestation areas in the municipality of Tailandia, northeast paraense. Evaluated the PP [paricá x pueraria (Pueraria phaseoloides)], PA [paricá x acacia (Acacia mangium)] and P (monoculture paricá) systems conducted in 5 years by the company G.M. Sufredini Industrial LTDA and collected soil samples at a depth of 0-20 cm for analysis of pH, total C and N, H + Al, available P, exchangeable Ca, Mg, K and Al and calculated values of C/N, SB, T, V and m. The vegetative development of paricá was assessed by survival, mortality and the number of defective plants beyond the DBH. The results showed that the increase in nitrogen content of the soil in PP treatment, the low soil fertility in PA treatment, but where paricá achieved the highest average in diameter (DBH = 16.64 cm) and greater survival rate in P treatment (90.63%). It was concluded that the soil-plant relationship in paricá and pueraria systems and monoculture

The different tillage systems interfere with soil chemical attributes mainly due to the site of preparation techniques. The aim of this study was to determine, in two time evaluation periods, the changes in soil chemical attributes affected by three tillage systems in Yellow Oxissol. The experimental design consists of a randomized block design, with split-plot (Soil Tillage systems X Depths samples) with 3 repetitions in two evaluation periods (2009 and 2012). The treatments consisted of three tillage systems, being Conventional Tillage (CT); No-Tillage (NT) and Reforestation with Paricá (RP). The two depths sampled were 0-0.1 m and 0.2-0.3 m. The attributes were evaluated as pH, organic matter, macronutrients levels, exchangeable acidity and micronutrient level. The soil tillage systems significantly affected the soil chemical attributes. In the NT system, the chemical attributes Ca, Mg, MO, P, K, Mn and Zn are concentrated on the most superficial layer of the soil, whereas in the CT there is a distribution of these variables along the topsoil.

This study evaluated the nutrient content of the litter, testing different treatments with burning and no burning, of the vegetation, to identify which one provides better efficiency in operation and production of nutrients in different seasonal conditions. The study area is located on the property of the family farmer, initially selected by a diagnosis socioeconomic, community Benjamin Constant, in northeastern Para. Litter was collected during two periods: dry season (November) and rainy (March) in 2009. For the collection of litter samples, we used collectors measuring (0.25 × 0.25 m 2), which were placed directly on the soil surface. The collected material was stored in paper bags and taken to the laboratory for Chemical Analysis of the Brazilian Agricultural Research Corporation (EM-BRAPA), which was determined by analyses of macronutrients (N, P, K, Ca, Mg, Na) and micronutrients (Fe, Cu, Mn, Zn). The highest concentrations of macronutrients were found in N for agroforestry systems with and without burning in two seasons (wet and dry). All macronutrients showed influence of seasonality, which was verified by the wide variation in nutritional behavior. The decreasing concentration of nutrients was presented N > Ca > Mg > Na > K > P in agroforestry system with burning, with maximum values of all nutrients in the rainy season, and N, P, K, Ca, Na in higher concentrations in agroforestry system without burning, and showed only the Mg peak in agroforestry system with burning. The behavior of the concentration of nutrients was opposite to that observed one, for all elements analyzed showed a reduction in the concentrations of nutrients in the dry season. The decreasing concentration of nutrients was presented Fe > Mn > Zn > Cu.

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