ABSTRACT Soil macrofauna is an important indicator of soil quality, as it is sensitive to changes in the environment as a result of soil management, which includes soil chemical and physical properties and the diversity of cultivated species. This study aimed to evaluate the composition and structure of soil macrofauna under a no-tillage system in different crop sequences, with and without crop rotation, over two growing seasons: a rainy summer and a dry winter. The crop sequences were soybean/corn rotation in the summer and corn in the winter; soybean/corn rotation in the summer and sunn hemp in the winter; soybean monoculture in the summer and sunn hemp in the winter; and corn monoculture in the summer and corn monoculture in the winter growing season. The nutrient content of the crop residues left on the soil surface, soil chemical and physical properties, and soil macrofauna were determined. Functional plant groups (grasses or legumes) individually influenced the composition of soil macrofauna more significantly than the effect of crop sequence, with or without rotation, and growing season. Grasses favored an increased density of groups such as Oligochaeta, Isoptera, and Formicidae. In contrast, legumes contributed to the variation in the total density of individuals and Diplura and Coleoptera groups. Furthermore, the influence of functional plant groups (grasses or legumes) on the composition and density of soil macrofauna were related to soil chemical (P and N content) and physical properties (particulate organic carbon and soil moisture), which determined the composition of soil macrofauna groups.

ABSTRACT: The soil particles can be gathered through physical and/or chemical processes in association with the biological activity, leading to the formation of aggregates. Soil aggregates has several functions in the soil, increasing macroporosity and water circulation - consequently reducing soil erosion and mechanical resistance to root growth, contributing to greater fixation of plants to the soil and absorption of water and nutrients, and protection of intra-aggregate organic matter. The aggregates were initially classified morphologically and in terms of their stability. In recent years, another way of evaluating aggregates, regarding their formation or origin pathway, has gained prominence in the studies conducted in Brazil. As for their origin, the aggregates can be classified morphologically as physicogenic, biogenic, or intermediate. This manuscript presents the techniques used to sample aggregates, the morphological patterns for their distinction observed in different soil classes and management types, and the chemical and physical properties. Additionally, we present analyses that are not commonly used to evaluate aggregates but which have the potential to be used as tools for a better understanding of their origin and to evaluate their modifications when subject to different types of management. In practical terms, identifying the aggregate origin and determining the related attributes allows recognizing the effect of vegetation/soil/management on soil aggregate forming agents, mainly roots and soil fauna, which reflects soil quality. For future studies, and especially to determine the importance of biogenic aggregation in improving edaphic properties, we suggest the use of micromorphology, near-infrared spectroscopy, X-ray computed tomography, clay dispersion analyses in addition with chemical, physical, and biological analysis. This approach can contribute to the identification of other patterns related to pedogenesis and the pathways of aggregate formation.

O crescente nível de degradação das terras tem promovido a adoção de manejos agrícolas que busque aliar a produção agropecuária à conservação do solo. Entre esses, a prática da Integração Lavoura-Pecuária (ILP) tem intensificado-se no Centro-Oeste brasileiro. Com o objetivo de avaliar o efeito em longo prazo do sistema ILP e da sazonalidade, sob a comunidade da macrofauna edáfica e das frações oxidáveis do carbono orgânico total (COT) em áreas de cultivo e Cerradão, foi desenvolvido na Fazenda Cabeceira no município de Maracaju, MS, um estudo em que se mensurou a influência da ILP sobre as frações oxidáveis do COT e sobre a macrofauna edáfica. O sistema ILP está sendo utilizado nessa área desde 2003; o solo foi identificado como Latossolo Vermelho, localizado em área de relevo plano. As áreas amostradas possuem o seguinte histórico: soja/milho + braquiária/algodão/ aveia + pastagem/soja/formação da pastagem/pastagem; as amostragens foram realizadas na época seca, em que as culturas presentes eram pasto, milho+braquiária e algodão; e na chuvosa, com milho+braquiária, algodão e soja. Assim, as áreas nas duas épocas de avaliação foram: pasto/milho, milho+braquiária/ algodão, algodão/soja e uma área nativa de Cerradão. A amostragem foi realizada nas profundidades de 0-10, 10-20 e 20-30 cm, sendo feitas as seguintes determinações: análise da macrofauna edáfica, fracionamento granulométrico da matéria orgânica do solo (MOS) e frações oxidáveis do COT. As áreas não apresentavam delineamento experimental, sendo este um estudo de observação. Os dados foram comparados pelo teste de Kruskal Wallis a 5 % e por meio da análise de redundância. A compartimentalização da MOS pode ser utilizada para a avaliação da qualidade do manejo, sendo os compartimentos mais sensíveis as frações F1 e F2 de frações oxidáveis, pois são mais lábeis no solo, já as frações F3 e F4 são as mais recalcitrantes. Isoptera (cupim) pode estar atuando como agente humificador da matéria orgânica na área de Cerradão, contribuindo para maiores teores de F3 e F4, em relação à F1 e F2 na época seca. Esse padrão somente foi verificado na área de Cerradão, visto que nas áreas de produção, Isoptera é controlado pelo manejo. A falta desse inseto no sistema ILP pode estar reduzindo a estabilização da MOS nas frações F3 e F4.

The increasing level of land degradation has led to the adoption of agricultural management practices that seek to combine agricultural production and soil conservation. Among these, the practice of Crop-Livestock Integration (CLI) has intensified in West-Central Brazil. In order to assess the long-term effect of the CLI system and seasonality on the community of soil macrofauna and oxidizable fractions of total organic C in croplands and the Cerradão (Brazilian tropical savanna), a study was developed at the Cabeceira Farm in the municipality of Maracaju, State of Mato Grosso do Sul, which measured the effect of CLI on oxidizable fractions of total organic C and soil macrofauna. The CLI system has been used in this area since 2003. The soil was identified as a Latossolo Vermelho (Ferrasol), on flat land. The areas sampled have the following history of use: soybean/corn + brachiaria grass/cotton/oat + pasture/soybean/implantation of pasture/pasture. Sampling was carried out in two seasons, dry and wet. In the dry season, the crops were pasture, corn+brachiaria grass and cotton; in the rainy season there were corn+brachiaria grass, cotton, and soybeans. Thus, the areas in the two evaluation periods were pasture/corn, corn+brachiaria/cotton, cotton/soybeans, and an area of native Cerrado. Sampling was performed at the depths of 0-10, 10-20, and 20-30 cm, and the following determinations were made: analysis of soil macrofauna, particle size fractionation of soil organic matter (SOM), and oxidizable fractions of total organic C. The areas do not have an experimental design as this is an observational study. Data were compared by the Kruskal Wallis test at 5 % probability and through analysis of redundancy. Compartmentalization of SOM can be used to assess the quality of management, with the most sensitive compartments being the F1 and F2 fractions in the assessment of oxidizable fractions. These fractions are more labile in the soil, whereas the F3 and F4 fractions are more recalcitrant. Isoptera (termites) may be acting as a wetting agent of organic matter in the Cerrado area, contributing to higher levels of F3 and F4, compared to F1 and F2, in the dry season. This pattern was only observed in the Cerrado area since in the production areas, Isoptera is controlled by management practices. The lack of these insects in the CLI system may be reducing the stabilization of SOM in the F3 and F4 fractions.

Entre os diferentes tipos de organismos da macrofauna do solo, distribuídos em diversos tipos de habitats, com variados hábitos alimentares e ciclos de vida, alguns são capazes de responder rapidamente às alterações ambientais e, por isso, considerados bons indicadores do funcionamento dos ecossistemas. O presente trabalho teve como objetivo avaliar o efeito dos seguintes estádios sucessionais de Floresta Estacional Semidecidual Submontana do domínio ecológico da Mata Atlântica: floresta secundária estádio inicial (FSEI), floresta secundária estádio médio (FSEM), floresta secundária estádio avançado (FSEA) e uma área de pasto misto manejado (PMM) sobre a densidade, diversidade e composição da comunidade da macrofauna edáfica em duas épocas do ano, no município de Pinheiral (RJ). Para amostragem da macrofauna, foram retiradas oito amostras da serapilheira e da camada superficial (0-10 cm) do solo pelo método recomendado pelo programa Tropical Soil Biology and Fertility (TSBF), com adaptações. Predominaram Isoptera, Formicidae e Oligochaeta em FSEI, FSEM e FSEA e Formicidae e Oligochaeta em PMM. Não houve diferença significativa na densidade da macrofauna edáfica entre as áreas. Os maiores valores dos estimadores de diversidade utilizados (equabilidade de Pielou, riqueza total e média) foram encontrados em FSEA. Os valores de riqueza total mostraram aumento gradual de acordo com o estádio de sucessão, desde PMM até FSEI. Constatou-se maior número de indivíduos no solo do que na serapilheira em todas as áreas de floresta, nas duas épocas. Pela análise de componentes principais (ACP) realizada para os períodos seco e chuvoso, foi possível identificar maiores diferenças na composição das comunidades entre os estádios sucessionais para o período chuvoso. Nesta época, os estádios FSEM e FSEA estiveram associados a uma maior diversidade de invertebrados saprófagos e predadores do que PMM e FSEI, demonstrando influência do processo sucessional sobre a comunidade da macrofauna do solo.

Among a number of organisms that constitute soil macrofauna communities, distributed in different types of habitats, with varied foraging habits and life cycles, some are capable of a rapid response to environmental changes. These organisms are considered efficient indicators of the well-functioning of ecosystems. The main objective of this study was to evaluate the effects of the following succession stages of a seasonal semidecidous submontane forest of the Atlantic Forest domain: Secondary Forest Initial Stage - SFIS, Medium Stage - SFMS, Advanced Stage - SFAS and a Mixed and Managed Pasture - MMP on the density, diversity and composition of the edaphic macrofauna community, in two seasons, in the Pinheiral county (Rio de Janeito state, southeastern Brazil). The macrofauna assessment was carried out by collecting eight samples of litter and superficial soil layer (0-10 cm) using the method recommended by "Tropical Soil Biology Fertility Programme" (TSBF), with modifications. The predominant taxonomic groups were Isoptera, Formicidae and Oligochaeta in SFIS, SFMS and SFAE and Formicidae and Oligochaeta in MMP. No significant difference of edaphic macrofauna density between the areas was observed. The highest diversity estimator values: Pielou's evenness index, total and average richness were observed in SFAE. The total richness values increase gradually from MMP towards SFAE. A higher number of individuals colonized soil in relation to the litter microhabitat in all forest areas, in the two sampling seasons. The principal component analysis (PCA) performed separately for the dry and wet season indicated greater differences of the macrofauna communities between succession stages in the wet season. In this season, the stages SFMS and SFAE were associated to a higher saprophagous and predator diversity than in MMP and SFIS. These results demonstrate the influence of the succession stage on the soil macrofauna community.