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Purpose: This study was carried out to evaluate the effects of the tillage system and consecutive application of swine slurry for seven years on arbuscular mycorrhizal fungal abundance and infective propagules in Brazilian soil with crop rotation. Method: The spore density, the external mycelium, and the most probable number of infective propagules of mycorrhizal fungal abundance were assessed in soil samples from an Oxisol in a long-term field experiment in response to soil management (no-tillage and conventional tillage) and following successive application of swine slurry (0, 30, 60, 90 and 120 m³·ha-1·year-1). Results: A greater amount of external mycelium was observed in soil under no-tillage, while mycorrhizal fungal abundance spore density was greater in soil under conventional tillage. In soil under no-tillage, mycorrhizal fungal abundance infective propagules were more abundant; however, in soil with both management systems, this variable was reduced with different levels of swine slurry application. In no-tillage, the main source of mycorrhizal fungal abundance propagules is the external mycelium, while in conventional tillage, the main inoculum component is the spores. Conclusion: In this study, we verified that the application of swine slurry, with high phosphorus contents, reduces arbuscular mycorrhizal fungi propagules. However, these effects are mitigated in no-tillage systems compared to conventional tillage. [ABSTRACT FROM AUTHOR]

Purpose: This study was carried out to evaluate the effects of the tillage system and consecutive application of swine slurry for seven years on arbuscular mycorrhizal fungal abundance and infective propagules in Brazilian soil with crop rotation. Method: The spore density, the external mycelium, and the most probable number of infective propagules of mycorrhizal fungal abundance were assessed in soil samples from an Oxisol in a long-term field experiment in response to soil management (no-tillage and conventional tillage) and following successive application of swine slurry (0, 30, 60, 90 and 120 m3·ha-1·year-1). Results: A greater amount of external mycelium was observed in soil under no-tillage, while mycorrhizal fungal abundance spore density was greater in soil under conventional tillage. In soil under no-tillage, mycorrhizal fungal abundance infective propagules were more abundant; however, in soil with both management systems, this variable was reduced with different levels of swine slurry application. In no-tillage, the main source of mycorrhizal fungal abundance propagules is the external mycelium, while in conventional tillage, the main inoculum component is the spores. Conclusion: In this study, we verified that the application of swine slurry, with high phosphorus contents, reduces arbuscular mycorrhizal fungi propagules. However, these effects are mitigated in no-tillage systems compared to conventional tillage. Highlights Swine slurry application in soil reduces infective propagules of mycorrhizal arbuscular fungal. Soil disaggregation caused by conventional tillage increases sporulation and reduces infective propagules of mycorrhizal arbuscular fungal. Reduction of infective propagules of mycorrhizal arbuscular fungal under swine slurry application is mitigated in no-tillage systems.

The main goal of this study was to determine the diversity and activity of arbuscular mycorrhizal fungi (AMF) in an area degraded by limestone mining within the semi-arid region of Brazil known as the caatinga (shrublands). Near a limestone quarry, we selected two areas of caatinga (preserved and degraded) for study. The number of glomerospores did not differ significantly between the two areas. There was a trend toward the most probable number of infective propagules being higher in the degraded area. Twenty AMF taxa were identified in the two sampled areas, species richness, diversity and evenness being higher in the preserved area. Two species of Racocetra represent new records for the semi-arid region of Brazil. Glomerospore production and AMF species richness were unaffected by mining activity in the study area.

Foi avaliado o efeito da mineração gesseira sobre os fungos micorrízicos arbusculares (FMA). Amostras de solo (10/área) foram coletadas em quatro áreas de uma mineradora: caatinga nativa (CN), arredores da mina (AM), rejeito (R) e interface entre o rejeito e caatinga degradada (IN), nos períodos chuvoso (dezembro/2003) e seco (setembro/2004). Foram registradas 42 espécies de fanerógamas: 25 na CN, 14 nos AM, 10 na IN e cinco na R. A CN apresentou maior número de espécies vegetais, esporos e propágulos infectivos de FMA. Número de esporos e colonização radicular diferiram entre os períodos. Maior esporulação ocorreu no período chuvoso, o número mais provável (NMP) de propágulos e colonização foram maiores no seco. Houve correlação positiva entre NMP e esporos nos dois períodos. No período chuvoso, o NMP foi negativamente correlacionado com colonização. Esta foi maior nas áreas AM e R. A atividade mineradora diminuiu a diversidade vegetal, o NMP de propágulos e a quantidade de esporos em relação à caatinga nativa.