Carlos Roberto Espindola

Atividade microbiana em um Latossolo degradado tratado com lodo de esgoto

Em geral, os solos degradados se apresentam com fraca atividade biologica, tendo em vista suas caracteristicas fisicas, baixa fertilidade e teores de materia orgânica, devido principalmente a remocao ou degradacao de sua camada superficial. O elevado teor de materia orgânica facilmente decomposta do lodo de esgoto, que e uma fonte alternativa de residuos orgânicos, aliado a sua elevada taxa dos principais elementos nutrientes as plantas, pode ser um fator importante do retorno ou incremento da atividade biologica dos solos degradados. Com a finalidade de se estudar as acoes do lodo de esgoto na recuperacao de um Latossolo degradado, utilizaram-se, como indicadores dos efeitos, o carbono na biomassa microbiana (Cmic), o carbono do CO2 (C-CO2) liberado e a relacao entre o carbono microbiano e o carbono orgânico (Cmic/Corg); para isto, foram definidas duas doses de lodo de esgoto aplicadas em cobertura e incorporada, de 30 e 60 Mg ha-1 a base seca, juntamente com um tratamento com fertilizante mineral, utilizando-se o eucalipto como cultura teste. O delineamento experimental foi o inteiramente casualizado, com 4 tratamentos e 4 repeticoes. O lodo de esgoto promove aumento do C-CO2 liberado e do Cmic, os quais constituem indicativos de qualidade adequados ao monitoramento da recuperacao do solo.

Alterações em características químicas de solos da região amazônica pela introdução de pastagens

The aim of the present work is to evaluate the effects of the human intervention, through the introduction of pasture, in some chemical properties of the Amazon soil. This research was installed in Porto Velho, State of Rondonia - Brazil, located vicinity of the Empresa Brasileira de Pesquisa Agropecuaria (Embrapa). The samples were accomplished in areas of primary vegetation and planted pasture (about 15 years), obeying a line with 24 points each 10 meters (12 under natural vegetation and 12 under pasture) in two horizons (superficial and undersuperficial). The results obtained for chemical compounds showed significant between forest and pasture to V%, CEC, C+Al, N-total and C-organic, mainly in the superficial horizon of the original vegetable. The higher organic compounds (N-total, C-organic) and P, Ca e Mg, in the superficial horizon of natural vegetation, wintry in Amazon Forest were observed.

Physical properties of soils under intensive agricultural management

Pedologic alterations after long-term sugar cane (Saccharum officinarum) cropping cycles under traditional soil management systems were studied on a farm in Bariri, SP, Brazil. A toposequence was established to evaluate the effects of the soil position in the relief in changing soil physical attributes. Morphological field descriptions and laboratory analyses were carried out on vertical profiles of the upper, middle and lower thirds of a Typic Haplorthox slope. Soil bulk density and macroporosity changed along the toposequence reflecting on soil hydrodynamics, especially in the lower slope parts. At sites with high clay levels, empty spaces were filled forming block shaped structures together with the micro-aggregate structure. The intensive cultivation induced the greatest soil structure alterations, even at the deepest layers. The study pointed out the importance of performing detailed morphological observations in vertical profiles, due to the great variation on pedological attributes over short distances. Compacted soil sections were observed side-by-side with desaggregated mottles in the same soil profile. This fact evidenced that both vertical (in each profile) and horizontal gradients (along a toposequence) need to be considered in studies of time sequence variation of pedological parameters.

Alteração física e morfológica em solos cultivados sob sistema tradicional de manejo

O presente trabalho foi realizado numa area agricola situada no municipio de Bariri (SP), em area cultivada com citros (Citrus sinensis), onde foram estudadas algumas alteracoes pedologicas decorrentes de um longo periodo de exploracao agricola com sistema tradicional de manejo do solo. Foi estabelecida uma condicao de sequencia topografica para que pudesse ser avaliada a importância da posicao dos solos no relevo sobre as modificacoes de alguns dos seus atributos fisicos. As observacoes foram realizadas em campo e laboratorio, em perfis verticais situados nos tercos: superior, medio e inferior da encosta em um Latossolo Vermelho com alguns atributos avaliados estatisticamente por meio de teste de comparacao de medias. Houve alteracoes na densidade do solo e da macroporosidade, principalmente nas posicoes mais baixas do relevo. Nestas posicoes, mais argilosas, ha preenchimento dos espacos vazios, com a formacao de estrutura em blocos, ocorrendo concomitantemente com a estrutura microagregada. Os tratos culturais promoveram grandes alteracoes na estrutura dos solos, mesmo em camadas relativamente profundas. O estudo ressaltou a importância de observacoes morfologicas detalhadas dos perfis de solo, em virtude da grande variabilidade dos atributos pedologicos a uma curta distância, sendo observados, num mesmo horizonte do perfil, setores compactados ao lado de bolsoes desagregados, o que atesta a necessidade de serem considerados tanto os gradientes verticais (em cada perfil) como os laterais (ao longo da topossequencia) no estudo das variacoes temporais dos parâmetros pedologicos.

Alteração física e morfológica em solos cultivados com citros e cana-de-açúcar, sob sistema tradicional de manejo

The continuos use of the soil interferes in its intrinsic characteristics, which changes according to the use and management applied. This present study evaluates some pedologic alterations, resulting from traditional soil management system, in citrus (Citrus sinensis) and sugar cane (Saccharum officinarum) fields subjected to extended planting cycles for a long period. Field and laboratory observations were undertaken in vertical profiles of the Red Latosol in Bariri County, State of Sao Paulo when morphological descriptions and laboratory analyses (particle size distribution, porosity, bulk density, organic matter, water infiltration rates and micromorphology) were established with some parameters evaluated by means of measure comparisons. The results obtained revealed that the intensive cultivation practices promoted significant soil structure alterations, with difficulty to root growth in both cases. In sugar cane fields, the intensive management promoted great soil structure alterations even in the deeper layers with changing in the voids geometry, which cause planar voids and fissures. In citrus cultivation, the deeper root systems and reduced soil mobility worked together for a greater aggregate stability, promoting adequate root development compared to the sugar cane.

A PEDOLOGIA E A EVOLUÇÃO DAS PAISAGENS

Geomorphology and pedology were developed in different times and use different methods for landscape analysis, presenting a morphogenesis-pedogenesis duality approach. Each phase of relief evolution was related to a distinct soil development state. Tectonic processes and climatic changes are important factors to be considered in this study. The relative ages attributed to the associated surfaces were mainly based on laterite, stone lines and paleosol occurrences. New developments on science showed that particular processes related to soil development (autoevolution) can create new relief patterns, confirming that soil is a real factor for relief formation. Sedimentological and absolute dating methods associated with conventional studies of pedon transformation in toposequences made it possible to imagine a morphopedogenesis or pedomorphogenesis science, since soil and relief form an indissoluble unity affected by the same factors.

SIAT - Sistema de Avaliação de Terras

The purpose of this work was to adapt the MicroLEIS - Land Evaluation Information System developed in Spain to the Brazilian Southeast conditions. Twelve (12) variables were considered, as follows: A - Relief Factor: 1) Slope; B - Soil Factor: 2) Effective depth, 3) Texture, 4) Stoniness, 5) Drainage, 6) Salinity; C - Erosion Factor: 7) Erodibility, 8) Slope, 9) Vegetation density, 10) Rainfall erosivity; D - Bioclimatic Deficiency Factor: 11) Frost, 12) Available water. For each of them, the control parameters were changed, according to conditions of the soils of the State of Sao Paulo. In this case, salinity was substituted by the pH. As a second step, the SIAT was interfaced with the GIS - Geographic Information System - IDRISI, to facilitate the data input, processing and spatialization of the results. The program structure was changed from Basic to C, and a database (Clipper) and routines were introduced so as to make the system more friendly. The modified system was tested in the Leme - SP region, showing good results in larger scale, although it is more indicated for regional evaluations at scales between 1:100,000 and 1:50,000.

Spatial analysis of soil physical attributes from a degraded area under different types of management.

The objective of this work was to analyze the spatial variability of soil aggregates, porosity and density under five different land-uses and management conditions (degraded substrate - SD; degraded substrate with sewage sludge and Eucalyptus crop - SDLE; soil under pasture SP; capoeira under regeneration - SR; and soil under cerrado - SC). Total porosity (m3.m-3) and density (Mg m-3) of the soil; the mean weight diameter (MWD, mm) of the aggregates; and the percentage of aggregates resistant to rainfall were evaluated. The date of soil was analyzed with descriptive statistics for initial exploration and geostatistics, to analyze the spatial variability. There was spatial dependency and the parameter adjust range varied from 8 to 12 m under the treatments SD and SR for the aggregates and SR for macroporosity, total porosity and soil density. There was spatial dependency also under SP, for the aggregates, microporosity, and total porosity; under SC, for the aggregates; and under SDLE, for microporosity. Soil data with spatial dependence in the field were characterized both by high and low values in the same area. Therefore it is not adequate to consider these areas as homogeneous for future experiments and agricultural activities.