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| Farias,Samuel Christian Cohen; Silva Júnior,Mário Lopes da; Ruivo,Maria de Lourdes Pinheiro; Rodrigues,Possidônio Guimarães; Melo,Vânia Silva de; Costa,Adriane da Rocha; Souza Júnior,João Cardoso de. |
| ABSTRACT The use of fire to prepare agricultural areas is a technique still used by small farmers in eastern Amazon. This type of management changes the dynamics of soil nutrients, especially phosphorus, which constitutes the most limiting nutrient for crop production in tropical soils. This study was carried out to evaluate changes in phosphorus forms in an Argissolo Amarelo Distrófico (Ultisol) submitted to burning and trituration of secondary forest in eastern Amazon. The evaluated systems were: slash-and-burn of vegetation; slash-and-mulch of vegetation; and secondary vegetation. The labile, moderately labile, moderately recalcitrant, available and total phosphorus fractions were assessed at the soil depths of 0.00-0.05, 0.05-0.10 and 0.10-0.20 m. The... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Shifting cultivation; Tropical soils; Phosphorus fractions; Organic phosphorus. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832016000100506 |
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| Silva Júnior,Mário Lopes da; Desjardins,Thierry; Sarrazin,Max; Melo,Vânia Silva de; Martins,Paulo Fernando da Silva; Santos,Elaine Rodrigues; Carvalho,Claudio José Reis de. |
| Soil plays an important role in the C cycle, and substitution of tropical forest by cultivated land affects C dynamic and stock. This study was developed in an area of expansion of human settlement in the Eastern Amazon, in Itupiranga, State of Pará, to evaluate the effects of native forest conversion to Brachiaria brizantha pasture on C contents of a dystrophic Oxisol. Soil samples were collected in areas of native forest (NF), of 8 to 10 year old secondary forest (SF), 1 to 2 year old SF (P1-2), 5 to 7 year old SF (P5-7), and of 10 to 12 year old SF (P10-12), and from under pastures, in the layers 0-2, 2-5 and 5-10 cm, to evaluate C levels and stocks and carry out separation of OM based on particle size. After deforestation, soil density increased to a... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Soil carbon stock; Particle-size fractions; Tropical soil; Amazon rain forest. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832009000600009 |
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| Silva,Sandra Andréa Santos da; Santos,Maria Marly de Lourdes Silva; Silva,George Rodrigues da; Silva Júnior,Mário Lopes da; Ohashi,Orlando Shigueo; Ruivo,Maria de Lourdes Pinheiro. |
| Este trabalho teve como objetivo avaliar o teor de cálcio e o efeito do ataque da lagarta H. grandella em plantas jovens de mogno (S. macrophylla), cultivadas em função de diferentes épocas de aplicação de doses crescentes de cálcio no substrato sílica moída, utilizando sistema hidropônico. O experimento foi instalado em casa de vegetação na Universidade Federal Rural da Amazônia (UFRA), Belém-PA, de setembro de 2004 a fevereiro de 2005. Utilizou-se cinco doses de cálcio (0, 80, 160, 240, 320 mg Ca.L-1), em solução nutritiva proposta por Hoagland & Arnon, modificada por Epstein (1975). O delineamento experimental foi inteiramente casualizado (DIC), as variáveis utilizadas para avaliação foram a susceptibilidade do mogno ao ataque da broca H.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Swietenia macrophylla; Hypsipyla grandella. |
| Ano: 2009 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672009000200005 |
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