ABSTRACT. Studies regarding soil quality and health often need to be up-to-date, as they feed new models for quantifying agricultural impacts on the environment. This study was established to understand how types of vineyard cultivation (organic and conventional) affect soil chemical and microbial attribute dynamics throughout different seasons. Vineyard management had a strong effect on chemical soil attributes. Organic carbon and phosphorus were 2.8 and 2.0 times greater, respectively, in organic vineyards than in conventional vineyards. Metabolic quotient (qCO2) values were lowest in summer and autumn, with an average of 2.31-2.49 µg C-CO2 h-1 g-1 soil, under organic management, indicating greater microbial growing efficacy. Regardless of season and sampling position, organic soil had a higher C microbial biomass than conventional vineyards, with values ranging from 179.79 to 284.71 µg g-1 soil, which were similar to those of the adjacent forest soil. Overall, there were increases in both the microbial and the chemical attributes of soil under organic vineyards compared relative to conventional management, which might have been due to the continuous input of organic matter, crop rotation, and alternative plant protection and fertilizer compounds used in organic farming.

Abstract: Farmers sometimes sow soybean (Glycine max (L.) Merrill) in dry soil in the expectation of rain in the short time. However, the forecast may not confirm, letting the inoculated seeds in the dry soil indefinitely. We assessed the survival of inoculated Bradyrhizobium and physiological quality of soybean seeds sown in dry soil. In the first experiment, irrigation was applied with 2 h, 1, 4, 11, 18, or 21 days after sowing; in the second experiment, sowing was carried out 2 h, 1, 5, 12, 14, or 20 days before irrigation. Each time represented a treatment in a completely randomized design. Bradyrhizobium cells dropped from ~8-9 × 104 colony forming units per seed soon after inoculation to -60% at 2 h after sowing in dry soil, and decreased to close to zero with time in both experiments. Although there was no effect on germination (59% and 81% in the first and second experiments, respectively), the exposure to dry soil reduced the emergence speed index from 19.5 (2 h) to 12.0 (21 days) in the first experiment and from 37.8 (2 h) to 13.8 (21 days) in the second. In the first experiment, the number of abnormal seedlings increased from 7% (2 h) to 24% (21 days); in the second, cotyledons showed cracks, which increased from 1% (2 h) to ~50% (≥ 5 days). Sowing in dry soil negatively affects not only the inoculated Bradyrhizobium, but also the physiological quality of soybean seeds.

Resumo: Em alguns casos os agricultores semeiam a soja (Glycine max (L.) Merrill) no solo seco, na espera de ocorrência de chuvas no curto prazo. Entretanto, a previsão pode não se confirmar, fazendo com que as sementes inoculadas permaneçam no solo seco indefinidamente. Avaliou-se a sobrevivência de Bradyrhizobium e o efeito sobre a qualidade fisiológica de sementes de soja inoculadas e semeadas em solo seco. No primeiro experimento, a irrigação foi aplicada com 2 h, 1, 4, 11, 18 ou 21 dias após a semeadura; no segundo experimento, a semeadura ocorreu 2 h, 1, 5, 12, 14 ou 20 dias antes da irrigação. Cada tempo representou um tratamento em delineamento inteiramente casualizado. A recuperação de Bradyrhizobium caiu de ~8-9 × 104 unidades formadoras de colônias por semente logo após a inoculação para -60% 2 h após a semeadura em solo seco, e tendeu a zero com o tempo, em ambos experimentos. Apesar de não afetar a germinação (59% e 81% nos no primeiro e no segundo experimento, respectivamente), a exposição ao solo seco diminuiu o índice de velocidade de emergência de 19,5 (2 h) para 12,0 (21 dias) no primeiro e de 37,8 (2 h) para 13,8 (21 dias) no segundo. No primeiro experimento, o número de plântulas anormais aumentou de 7% (2 h) para 24% (21 dias); no segundo, os cotilédones apresentaram trincas, que aumentaram de 1% (2 h) para ~ 50% (≥ 5 dias). A semeadura em solo seco prejudica não apenas o Bradyrhizobium inoculado, mas também a qualidade fisiológica das sementes de soja.

O cultivo orgânico com inclusão de material orgânico fresco altera propriedades físicas e químicas do solo e, com isso, pode resultar em modificações nas características biológicas deste. Assim, o objetivo deste estudo foi estudar os efeitos do manejo da videira (Vitis labrusca L.) sobre as propriedades químicas e microbianas do solo. Em outubro de 2006, amostras de solo foram coletadas de dois experimentos instalados em 2000 e de uma área adjacente com floresta. Os seguintes tratamentos foram avaliados em um esquema fatorial 2 x 2 x 2: (i) orgânico (ORG) e convencional (CONV); (ii) dos cultivares (IAC-766/Isabel e IAC-766/Bordô); e (iii) da heterogeneidade espacial (linha e entrelinha) sobre as propriedades químicas e microbianas de um solo arenoso. Foi observada a formação de três grandes grupos (CONV, ORG/linha e ORG/entrelinha), que se destacaram na área de floresta. As variáveis químicas e microbianas, com exceção do K, foram alteradas em relação aos manejos da videira. Houve efeitos do cultivar no N da biomassa microbiana e na respiração basal (CO2). Também foram observados efeitos de heterogeneidade espacial do solo no C da biomassa microbiana e em atributos químicos, como P, pH, Mg e micronutrientes. No sistema orgânico da videira, aumentaram-se o carbono orgânico do solo (COS) e a biomassa microbiana na linha e entrelinha, em comparação com a videira convencional. Os aumentos foram de 172 % no SOC, 100 % no Cmic e 223 % no Nmic, na linha do orgânico. Os manejos da videira e a heterogeneidade espacial do solo foram os fatores mais relevantes no agrupamento (ou separação) das áreas devido às mudanças nos atributos químicos do solo, principalmente o COS, e na biomassa microbiana.

Organic cropping systems with input of fresh organic matter can modify the physical and chemical properties of soils and consequently affect their biological composition. The purpose of this study was to determine the effects of juice grape (Vitis labrusca L.) management on the soil chemical and microbial properties of a sandy-textured Oxisol. In October 2006, soil was sampled from two vineyard experiments set up in 2000, and from a neighboring forest area. The following treatments were evaluated in a 2 x 2 x 2 factorial design: (i) organic (ORG) and conventional (CONV) vineyard managements; (ii) cultivars in rootstock/graft combinations: grafts Isabel and Bordô on rootstock IAC-766 and (iii) spatial heterogeneity (row and inter-row). Based on the analyses, the vineyard soils were separated in three groups (CONV, ORG/row and ORG/inter-row), which differed from the adjacent forest area. All microbial and chemical variables, except K, were modified in the vineyards. Rootstock/graft cultivar combinations affected the N microbial biomass and basal respiration (CO2), while P, pH, Mg, micronutrients, and C microbial biomass were influenced by spatial heterogeneity. Soil Organic C (SOC) and microbial biomass in the rows and inter-rows were higher in the organic than the conventional vineyard management. In the rows under organic management, SOC was 172 % higher, Cmic 100 % and Nmic 223 % than in CONV. The same was observed in inter-rows, but to a lesser extent. The most relevant factors differentiating areas by changes in soil chemical properties, mainly SOC, and in microbial biomass were mainly caused by the vineyard management and soil spatial heterogeneity.