Luís Antônio Coutrim dos Santos

Caracterização de terras pretas arqueológicas no sul do estado do Amazonas

The Archaeological Dark Earth (ADE) soils are characterized by its high fertility, dark color, and presence of pottery fragments. Regarding the formation of ADE, the most widely accepted hypothesis is that anthropogenic processes involving pre-Columbian populations made them. The purpose of this study is to characterize ADE units located in the Southern Amazon Region, in the cities of Apui and Manicore. Seven ADE sites were selected, trenches opened and the soil profiles characterized morphologically. Then, samples of each horizon were collected for analyses of the following physical and chemical properties: particle size, water-dispersible clay, flocculation, soil bulk density, particle density, total porosity, pH in water and KCl solutions, Ca2+, Mg2+, K+, Al3+, available P, H+Al, and organic C. Also, total oxides, free oxides and amorphous forms were analyzed. The texture of the anthropic A horizon ranged from sandy loam to clay loam. The pottery fragments and lithic material were found in similar quantities and at similar depths in the A horizons of the studied soil profiles, suggesting some similarity between the anthropogenic factors of formation. The anthropic horizons of profiles P3, P4, and P7 had a eutrophic character and high to very high levels of available phosphorus, compared to P1, P2, P5, and P6, indicating the heterogeneity of the ADEs.

Growth of cowpea cultivars in upland and lowland soils

O feijao caupi apresenta grande importância na alimentacao especialmente das populacoes das regioes norte e nordeste brasileiro, sendo uma das principais fontes de energia e proteina nestas localidades. Entretanto, as produtividades obtidas geralmente sao baixas, o que poderia ser contornado utilizando-se solos de maior fertilidade natural. Assim, o objetivo neste trabalho foi avaliar o crescimento de tres cultivares de feijao caupi cultivado em solo de terra firme e de varzea, na regiao de Humaita, Amazonas. O experimento foi conduzido em casa de vegetacao, utilizando-se sacos de polietileno de aproximadamente 2 litros. Como substrato, foram coletadas amostras de solos na profundidade 0,0 a 0,20 m, de Argissolo Vermelho (terra firme) e Neossolo Fluvico (varzea). Foram utilizadas na semeadura as cultivares: Barrigudinho, Manteiguinha e Felipinho. O delineamento estatistico utilizado foi em blocos completos casualizados, em esquema fatorial 2x3, com quatro repeticoes. Foram avaliadas as seguintes caracteristicas: altura da planta, diâmetro do coleto, biomassa seca e verde da parte aerea e radicular. Verificou-se que o solo de varzea e mais propicio ao cultivo do feijao caupi, devido a sua fertilidade natural. Nao ha diferenca no crescimento vegetativo das cultivares de feijao estudadas, independentemente do cultivo em solo de varzea ou terra firme. Abstract The cowpea is important especially in feeding the populations of northern and northeastern Brazil, it is a main source of energy and protein in these places However, the yields are low generally, which could be overcome using higher natural fertility soils. The aim was to evaluate the growth of three cultivars of cowpea grown in soil “terra firme” and “ varzea ” in the region of Humaita , AM . The experiment was performed in a greenhouse, using polyethylene bags of about 2 liters. Soil samples were collected at a depth from 0.0 to 0.20 m, Typic Hapludalf (terra firme) and Fluvic Neosol (varzea), the cultivars used for varieties: Barrigudinho , Manteiguinha and Felipinho . The statistical design was randomized blocks in factorial 2x5, with four replications. The parameters used in assessing the growth of plants were: plant height, stem diameter and dry biomass of green shoots and roots. It was found that the meadow soil is more conducive to the cultivation of cowpea, due to its natural fertility. There is no difference in vegetative growth of bean varieties studied, regardless of the crop in “ varzea ” or “ terra firme ”.