Efficacy of alginate- and clay-encapsulated microorganisms on the growth of Araçá-Boi seedlings (Eugenia stipitata)

The present work aimed to evaluate the effects of encapsulated microorganisms on seedlings of Eugenia stipitata, popularly known as araçá-boi, to evaluate the interaction between the inoculum and encapsulating agents such as clay and alginate. The experiment was carried out in a completely randomized design using a 3×2 factorial scheme. The treatments were control, inoculum, clay without microbial inoculum, clay with microbial inoculum, alginate without microbial inoculum, and alginate with microbial inoculum. The seedlings were grown under nursery conditions over a period of 3 months. No treatment increased the height, stem diameter, shoot dry matter or root dry matter of the araçá-boi seedlings. The use of alginate increased the ammonium content compared to the clay and control treatments. Alginate and clay increased the nitrate content in relation to the control. Alginate increased the total number of bacteria in relation to the clay and control treatments. The application of inoculum combined with alginate increased the nitrate content only in relation to the clay and control treatments. Although the application of inoculum promoted an increase in the nitrate content compared to the uninoculated treatments, there was no effect for the other parameters analyzed. The results suggest that clay and alginate encapsulating agents with the presence or absence of microorganisms may improve some soil parameters.

Atributos químicos, físico-hídricos e mineralogia da fração argila em solos do Baixo Amazonas: Serra de Parintins / Chemical, physical and hydric attributes and mineralogy of clay fractions in soils of lower Amazon: Serra de Parintins

Estudos sobre os atributos dos solos amazônicos geram informações para compor um levantamento atual sobre suas condições frente às várias formas de alterações que estão sujeitos. O objetivo deste trabalho foi descrever e avaliar a evolução química, físico-hídrica, bem como a mineralogia de Latossolos no Baixo Amazonas como forma de entender as variações desses atributos em diferentes coberturas vegetais. Coletaram-se amostras deformadas e indeformadas para análises físicas, químicas, mineralógicas e hídricas, em dois pontos de uma topossequência na Serra de Parintins: platô e vertente, sendo três perfis de solo em cada posição. Os resultados obtidos demonstraram que a floresta predominante sobre os perfis do topo e vertente promove condições físicas e hídricas adequadas para uma boa agregação, maior intensidade de poros grandes, maior condutividade hidráulica saturada (Ko) e melhor retenção hídrica dos solos. Fato semelhante ocorrendo com as áreas de capoeira, apresentando boa permeabilidade, porosidade e retenção de água no solo. O acúmulo de carbono é maior dos perfis da vertente, decrescendo em profundidade, relacionando-se diretamente com Ko e com o sistema radicular. A análise mineralógica da fração argila indicou a caulinita como argilomineral predominante, seguido pelos minerais gibbsita, goethita, quartzo e anatásio, não havendo variações ao longo da paisagem. A Serra de Parintins possui um solo pobre em nutrientes, ácido, com textura média a muito argilosa com acúmulo de plintita nos horizontes subsuperficiais, evitando o fenômeno de terras caídas. Um gradiente elevado de umidade volumétrica é observado nos horizontes subsuperficiais, havendo mais água retida, quando comparado com horizontes superficiais.

The latest studies of attributes of soil of the Amazonian ecosystems provide information to make up a survey on these soil conditions in the face of several forms of changes they are submitted. This work aimed to describe and evaluate physical and hydric evolution as well oxisol mineralogy in lower Amazon in order to comprehend variations of these attributes in different vegetative covers. Deformed and non-deformed samples were collected for physical, chemical, hydric and mineralogical analyses, respectively in two points of a topographic sequence in Serra de Parintins: plateau and watershed, being showed three profiles of soil in each position. The results showed that predominant forest of the plateau and watershed profiles provide proper physical and hydric conditions for a good aggregation, higher intensity of large pores, larger saturated hydraulic conductivity (Ko) and better hydric retention of soils. Similar fact occurs in secondary forest, presenting such areas good permeability, porosity and water retention in soil. Carbon accumulation is higher in watershed profiles, decreasing in depth and relating directly with Ko and root system. Mineralogical analysis of clay fraction points kaolinite as predominant followed by gypsum, goethita, quartzo and anatásio, showing no variations along landscape. Serra de Parintins has poor acid clay soil of medium texture accumulating plintita on subsurface horizons, avoiding the phenomenon of terras caídas. A high gradient of volumetric humidity is observed on subsurface horizons, showing water retention when compared to surface horizons.