A. Reatto

Características físicas de um latossolo vermelho-escuro no Cerrado de Planaltina, DF, submetido à ação do fogo

Os principais efeitos do fogo como manejo de solo estao relacionados a alteracoes biologicas e quimicas do solo. A queima pode ainda alterar a umidade do solo em razao de mudancas na taxa de infiltracao, na taxa de transpiracao, na porosidade e na repelencia do solo a agua. O objetivo deste trabalho foi avaliar as caracteristicas fisicas de um Latossolo Vermelho-Escuro muito argiloso, plano, fase campo cerrado, submetido a acao do fogo, apos ser utilizado durante 20 anos em pastagem nativa sem queima. Uma area de 1,25 ha foi submetida a acao bienal do fogo, e uma area adjacente, do mesmo tamanho, foi mantida protegida da acao do fogo. Apos seis anos, nao houve variacoes marcantes nas caracteristicas fisicas do solo induzidas pelo fogo, exceto no aumento da umidade do solo nas parcelas nao queimadas. Nas parcelas onde se aplicou o fogo, observou-se tendencia para o aumento da microporosidade, que pode ser atribuida a compactacao promovida pelo impacto das gotas de chuva no solo desnudado pelo fogo. Conclui-se, entretanto, que a queima bienal nao foi suficiente para provocar degradacao no periodo estudado.

O solo como fator de integração entre os componentes ambientais e a produção agropecuária

The central theme of this Thematic Issue on Soils is “Soil as an integrating factor between environmental components and agricultural production”. From this central theme, the papers were divided into the three following sections, according to the major areas of knowledge addressed: Soil and Planning, Soil and Production, and Soil and Environment, as well as their connections (Figure 1). In the section Soil as a support for Planning, priority was given to contributions that would increase the knowledge of the interrelations between soils and landscape components, and that addressed the implications of these interrelations for the strategic planning of land use, supported by geospatial tools. Issues such as soil characterization and digital mapping, precision agriculture, and zoning of environmental components – which are models that guide the sustainability of agricultural production – are discussed singly or together. In the section Soil as an integrating factor of the Environment, priority was given to contributions on soil ecosystems and on environmental services, such as: soil’s role in the landscape functioning; impacts of human activities on the provision and maintenance of environmental services; emission of greenhouse gases in various land uses; environmental quality in areas under remediation; and soil pollution. In the section Soil as substrate for Production, priority was given to contributions on conservation tillage systems and their impacts on the quality of soil and water, including: studies with the quantification of the effects of management systems on the physical, chemical, and biological indicators of soil quality, highlighting their implications for soil and water conservation practices; studies with an integrative approach on the effects of soil biology, physics, and fertility on agricultural production; and studies that addressed the tropicalization of fertilizers, its implications on nutrient bioavailability, and its impacts on the environment. The following is a summary of the papers published in each section of this Thematic Issue on Soils.