Alteration in soil fauna due to soil management and crop rotation in a long-term experiment

The evaluation of the population of meso and macrofauna organisms has been receiving attention in different studies related to soil quality. Therefore, the present study had as objective to evaluate the population of macro and mesofauna organisms, in an experimental area installed for 26 years in Paraná / RS. Among the 11 existing treatments, six were selected by lot, grew in a Conventional and No-tillage system. Soil fauna organisms were captured at 10 cm depth. The method used for the extraction of edaphic organisms was Tüllgren funnel. The collections were executed in blocks and repetitions that represented 312 samples. In the autumn, 60,138 m-2 individuals were estimated, and in the summer they were 28,348 m-2 individuals. The adoption of the long-term no-tillage system favors the biodiversity of the soil fauna in relation to the soil that has been undergoing two years of cultivation and four annual harrows since 1976. The native forest soil is more biodiverse than the cultivated one. The most representative edaphic taxon in the autumn were Acari, Collembola and Diptera, and in the summer they were Acari, Collembola, Hymenoptera and Larva of Lepidoptera. The phytosanitary management of the areas influence the diversity indexes of the edaphic fauna. The soil moisture abiotic factor acts severely under the edaphic fauna in the summer, being more evident in the conventional cropping system. The collection season conditioned to the abiotic factors - soil moisture and temperature - influences the density of individuals, species richness and the Shannon and Pielou indexes

Variações nos teores de carbono orgânico em função do desmatamento e revegetação natural do solo

The soil organic matter content is severely affected by soil use and management. In physically and chemically fragile soils the destruction of native vegetation can cause a great decrease in the carbon stock. However, soils that present high resilience, when appropriately handled, can easily recover the original values of carbon. The objective of this research was to quantify and analyze organic carbon of young soils in relation to their use, especially those in natural regeneration. Samples of two layers were collected (0-5 and 5-15 cm) in two soils (Neossolo and Chernossolo) that occur in a headslope watershed, with four use conditions (forest, new farming, old farming and regeneration). Particle size distribution, soil bulk density and organic carbon were evaluated. The data were submitted to statistical analysis considering a completely randomized design, in tri-factorial outline (soil types, uses and sampled layers). The soil carbon stock decreased with deforestation for annual plantation  of crops with little addition of residues and intensive soil turbation. The natural regeneration of degraded soils by conventional tillage recovered the soil carbon stock quickly, even when there remained impressions from erosion (lower clay) and from the application of fertilizers and correctives (lower potential acidity and larger phosphorus and potassium availability).A flutuação no conteúdo de matéria orgânica do solo é severamente afetada pelo uso e manejo do solo. Em solos física e quimicamente frágeis a destruição da vegetação nativa pode levar a diminuição drástica do estoque de carbono. No entanto, solos jovens que apresentam alta resiliência, quando manejados adequadamente, podem recuperar facilmente os valores originais de carbono. O objetivo deste trabalho foi quantificar os teores de carbono orgânico de um Neossolo e um Chernossolo em decorrência de seu uso, em especial após o desmatamento e revegetação natural. Coletaram-se amostras de duas camadas (0-5 e 5-15 cm) em dois solos (Neossolo e Chernossolo) ocorrentes numa pequena bacia hidrográfica com relevo fortemente ondulado, com quatro condições de uso (mata nativa, lavoura nova, lavoura velha e revegetação com capoeira). Avaliaram-se a distribuição granulométrica, a densidade do solo e os teores de carbono orgânico. Os dados foram submetidos à análise estatística considerando um delineamento inteiramente casualizado, num esquema trifatorial (tipos de solos, tipos de usos e camadas amostradas). O estoque de carbono do solo diminuiu após o desmatamento para a inastalação de culturas anuais com baixa adição de resíduos e revolvimento intenso do solo. A revegetação natural das áreas degradadas pelo cultivo convencional recuperou rapidamente o estoque de carbono dos solos, mesmo permanecendo as impressões herdadas da erosão (menor teor de argila) e da aplicação de fertilizantes e corretivos (menor acidez potencial e maior disponibilidade de fósforo e potássio)

Edaphic fauna in soil profile after three decades of different soil management and cover crops in a subtropical region

Abstract This research evaluated the effects of long-term (30 years) winter cover crops under conventional farming system and no-tillage system on edaphic fauna in a Rhodic Hapludox soil, from Paraná State, Brazil. We used three winter cover crops (black oat, hairy vetch and fallow), and as a reference a fragment of natural forest. Soil monoliths were collected at two times, one during the flowering of maize (April 2013) and the other during the flowering of soybean (January 2014). The extraction of the monoliths was carried out in three layers in the soil profile (0-10, 10-20 and 20-30 cm). Seventeen taxonomic groups were sampled. The density of the edaphic fauna is inversely related to soil depth. The winter crops associated with the no-tillage system in long-term resulted in fauna densities similar to the natural environment, with a higher density (density increase of 2.2x) at a depth of 10-20 cm in areas with black oat. At 0-10 cm depth, black oat and vetch under no-tillage systems resulted in an increase of 62% and 69% (April 2013) and 46 and 44% (January 2014), respectively, in the density of soil fauna, when compared to the same winter crops in conventional farming system

Soil fertility and nutrient budget after 23-years of different soil tillage systems and winter cover crops in a subtropical Oxisol

International audienc

Soil particle aggregation improvement through no-tillage system

O objetivo deste trabalho foi verificar os efeitos de sistemas de manejo na melhoria do solo, principalmente quanto aos índices de agregação do solo. Em um Latosolo Vermelho distroférrico muito argiloso, na região oeste do Paraná, foram avaliados os efeitos do plantio direto, com e sem rotação de culturas, e o sistema convencional (uma aração e duas gradagens), em comparação com a área de floresta, na capacidade de agregação das partículas do solo. O delineamento experimental foi de blocos ao acaso com três repetições. Os sistemas avaliados foram: 1) sistema plantio direto, incluindo plantas de cobertura e rotação de culturas (PD integral); 2) sistema plantio direto sem rotação de culturas previamente definida (PD tradicional); 3) sistema convencional (uma aração + duas gradagens no momento da implantação das culturas); e uma área de mata, utilizada como referência do estado original do solo. As amostras de solo foram coletadas em todos os tratamentos, e os índices de agregação do solo determinados foram: o diâmetro médio ponderado (DMP), o diâmetro médio geométrico (DMG) e o índice de estabilidade de agregados (IEA%). Também os teores de carbono orgânico foram determinados em todos tratamentos. Os maiores valores de carbono orgânico, e também IEA%, DMP, DMG foram encontrados na área de floresta, quando comparada aos demais tratamentos. O sistema de plantio direto, incluindo plantas de cobertura e rotação de culturas (PD integral) contribuiu para o aumento dos teores de carbono orgânico do solo, e também para um aumento do IEA%, DMP e DMG em ambos locais (Santa Helena e Entre Rios d’Oeste) em ambas profundidades do solo (0 – 10 e 0,10 – 0,20m). Os melhores índices de agregação observada são indicadores de qualidade no manejo desses solos. O sistema convencional provocou a dispersão das partículas de solo, e conseqüente diminuição dos índices de agregação (IEA %), provocando queda nos níveis de matéria orgânica do solo quando comparado aos demais tratamentos, e também apresentou os menores índices de DMP e DMG, assim como a mais baixa concentração de agregados > 2,00mm.The effects of no-tillage with and without crop rotation previously planned, conventional system including ploughing and disc harrowing on soil particles aggregation were evaluated and compared with native forest on an Red distroferric Oxisol with high clay content from western Paraná State. Soils were sampled from all treatments, adequately stored and soil aggregation indices determined were: the mean weight diameter (MWD), the geometric mean diameter (GMD) and the aggregate stability index (AS %). Soil organic carbon was also determined for the different treatments. The results showed highest soil organic carbon and also higher AS %, MWD and GMD for native forest area compared to all other treatments. The no-tillage system, cover crops use and crop rotation contributed to increase soil organic carbon levels, and also AS %, MWD and GMD in both localities and in both soil depths (0,0 – 0,10m and 0,10 – 0,20m). The conventional system, where soil are periodically disturbed provoking soil particles dispersion and soil aggregates collapse, promoted decreasing soil organic carbon levels compared to all other treatments, and also presented lower values for AS %, MWD and GMD, as well lowest aggregates > 2,00mm