Biossólido no estabelecimento de espécies herbáceas e nos atributos químicos e microbiológicos em solo impactado pela mineração de carvão / Biosolids in the establishment of herbaceous species and in chemical and microbiological attributes in soil impacted by coal mining

RESUMO O presente estudo tem como objetivo avaliar o efeito da aplicação de diferentes concentrações de biossólido de lodo de esgoto, submetido a tratamento térmico, no estabelecimento de espécies herbáceas (aveia preta, ervilhaca e azevém) e nos atributos químicos e microbiológicos de um solo degradado pela mineração de carvão. O experimento foi instalado em área degradada pela mineração de carvão, localizada no munícipio de Treviso (SC), sendo os tratamentos compostos pelas concentrações de 0, 6,25, 100, 250 e 500 Mg ha-1 de biossólido, em parcelas de 2×2 m. Foram cultivadas espécies de aveia preta, ervilhaca e azevém de maneira consorciada, avaliando-se os parâmetros das plantas e os atributos químicos do solo nas profundidades 0-5, 5-10 e 10-20 cm. O biossólido proporcionou a elevação do pH do solo e o aumento dos teores disponíveis de P, K e carbono orgânico total e não influenciou na colonização micorrízica, na respiração basal do solo e na nodulação radicular. O uso do resíduo biossólido como substrato em áreas degradadas é uma alternativa para sua disposição final pela economia ao utilizá-lo como fertilizante, além dos benefícios ambientais, associados ao seu uso.

ABSTRACT This study aims to evaluate the effects of different concentrations of sewage sludge biosolid concentrations, submitted to thermal treatment, in the establishment of herbaceous species (black oats, vetches, and ryegrass) and in the chemical and microbiological attributes of a soil degraded by coal mining. The experiment was installed in an area degraded by coal mining, in Treviso/SC, with treatments composed of concentrations of 0; 6.25; 100; 250; and 500 Mg ha-1 of biosolids, in 2×2 m plots. Species of black oat, vetch, and ryegrass were grown in a consortium manner, evaluating the plant parameters and chemical attributes of the soil at depths 0-5, 5-10, and 10-20 cm. The biosolids provided improvements in soil fertility, such as pH elevation, increased levels available of P, K, and total organic carbon, in addition to not influencing mycorrhizal colonization, basal soil respiration, and root nodulation. The use of biosolid waste as a substrate in degraded areas is an alternative to its final disposal due to the economy when using it as a fertilizer, in addition to the environmental benefits associated with its use.

Microbial activity in soil with onion grown in a no-tillage system with single or intercropped cover crops / Atividade microbiana em solo com cebola cultivada em sistema de plantio direto com plantas de cobertura solteiras ou consorciadas

ABSTRACT: Microbial biomass is a driving force in the dynamics of soil organic matter, and microbial activity is an indicator of soil quality in agroecosystems, reflecting changes in management practices and environmental conditions. We evaluated the effect of monoculture and intercropped winter cover crops on soil chemical attributes, microbial biomass carbon (MBC), basal respiration (BR), metabolic quotient (qCO2), urease, β-glucosidase, and fluorescein diacetate (FDA) hydrolysis activity, as well as onion yield in a no-tillage system. Soil is a Typic Humudept, and treatments were control with spontaneous vegetation, barley, rye, oilseed radish (OR), OR + rye, and OR + barley. The soil was sampled (0-10 cm) five times between June and December. There were no differences among treatments for MBC and BR, and the highest values for those attributes occurred in June, when cover plants were in their initial stage. Although, qCO2 was not affected by any treatment, it varied among sampling periods, ranging from 0.62 to 10 µg C-CO2 mg-1 MBC h-1, indicating a low- or no stress environment. Cover crops had little influence on enzyme activity, but FDA was lowered in areas with single crops of barley and rye. Average onion yield in cover crops treatments was 13.01 (Mg ha-1), 30-40% higher than in the control treatment.

RESUMO: A biomassa microbiana é determinante na dinâmica da matéria orgânica do solo e sua atividade é um indicador de qualidade do solo em agroecossistemas, refletindo mudanças em práticas de manejo e em condições ambientais. Avaliou-se o efeito de culturas de cobertura de inverno, solteiras ou consorciadas, sobre atributos químicos do solo, carbono da biomassa microbiana (CBM), respiração basal (RB), quociente metabólico (qCO2) e atividade das enzimas urease, β-glucosidase e FDA, bem como o rendimento da cebola em um sistema de plantio direto. O solo é um Cambissolo Húmico alumínico, os tratamentos foram testemunha com vegetação espontânea, cevada, centeio, nabo forrageiro (NF), NF + centeio e NF + cevada. Realizaram-se cinco coletas de amostras de solo (0-10 cm) entre junho a dezembro. Não houve diferenças entre os tratamentos para CBM e RB, e os maiores valores para esses atributos ocorreram em junho, quando as plantas de cobertura estavam em seu estágio inicial. Embora o qCO2 não tenha sido afetado por nenhum tratamento, ele variou entre os períodos de amostragem, com valores entre 0,62 e 10 µg de C-CO2 mg-1 MBC h-1, indicando um ambiente de baixo ou nenhum estresse. As culturas de cobertura tiveram pouca influência na atividade enzimática, mas o FDA foi reduzido em áreas com cultivos solteiros de cevada ou centeio. O rendimento médio de cebola nos tratamentos com culturas de cobertura foi de 13,01 (Mg ha-1), mais alto que no tratamento controle.

Effect of arbuscular mycorrhizal fungi on young vines in copper-contaminated soil

Abstract High copper (Cu) levels in uprooted old vineyard soils may cause toxicity in transplanted young vines, although such toxicity may be reduced by inoculating plants with arbuscular mycorrhizal fungi (AMF). The objective of this study was to evaluate the effects of AMF on the plant growth, chlorophyll contents, mycorrhizal colonization, and Cu and phosphorus (P) absorption in young vines cultivated in a vineyard soil contaminated by Cu. Commercial vineyard soil with high Cu levels was placed in plastic tubes and transplanted with young vines, which were inoculated with six AMF species (Dentiscutata heterogama, Gigaspora gigantea, Acaulospora morrowiae, A. colombiana, Rhizophagus clarus, R. irregularis) and a control treatment on randomized blocks with 12 replicates. After 130 days, the mycorrhizal colonization, root and shoot dry matter (DM), height increment, P and Cu absorption, and chlorophyll contents were evaluated. The height increment, shoot DM and chlorophyll contents were not promoted by AMF, although the root DM was increased by R. clarus and R. irregularis, which had the greatest mycorrhizal colonization and P uptake. AMF increased Cu absorption but decreased its transport to shoots. Thus, AMF species, particularly R. clarus and R. irregularis, contribute to the establishment of young vines exposed to high Cu levels.