Rhizosphere-associated microbiota of Canavalia ensiformis in sulfentrazone bioremediation.

The objective of this study was to determine the efficiency of the microbial rhizosphere (Canavalia ensiformis) in the phytoremediation of sulfentrazone using quantification methods (CO2 evolution, microbial biomass carbon, and metabolic quotient) and identification of bacteria (PCR-DGGE technique). The experiment was conducted in a completely randomized design, in a 2x4 factorial scheme, with four replications. The treatments were composed of rhizospheric soil (cultivated with C. ensiformis) and non-rhizosphere soil (uncultivated soil); and four levels of contamination by sulfentrazone (0, 200, 400, and 800 g ha-1 a.i.). The microbiota associated with the rhizosphere of C. ensiformis efficiently reduced sulfentrazone residues in the soil, with better performance at the dose of 200 g ha-1 a.i. Using the PCR-DGGE technique allowed the distinction of two profiles of bacteria in the rhizospheric activity of C. ensiformis. The second bacterial profile formed was more efficient in decontaminating soil contaminated with sulfentrazone residue. The microbiota associated with the rhizosphere of C. ensiformis has an efficient profile in decontaminating soils with residues equivalent to 200 g ha-1 a.i. the herbicide sulfentrazone.

Phytoremediation of soils contaminated with herbicide residues is a viable technique for decontamination of the environment.Canavalia ensiformis has an efficient profile in the decontamination of soils with residue equivalent to 200 g ha⁻¹ a.i. of the herbicide sulfentrazone.The PCR technique and microbial respiration used to analyze the diversity and estimate the bacterial population of a soil are viable tools to evaluate the phytoremediation potential of the microbiota associated with plant species.

Avaliação do uso de plantas de cobertura de solo na entressafra milho-trigo no noroeste do Rio Grande do Sul / Evaluation of the use of cover crops in corn-wheat off-seasonin northwest of Rio Grande do Sul

A utilização de plantas de cobertura de solo, em especial de verão em janelas entressafras, é uma prática pouco comum por competirem com as culturas de importância econômica. O objetivo foi avaliar o uso de plantas de cobertura, na cobertura do soloe supressão de plantas espontâneas na entressafra milho-trigo no noroeste do Rio Grande do Sul. Para isso, utilizou-se crotalária espectabilis, mucuna-cinza, feijão-de-porco, tremoço, trigo-mourisco, milheto, consórcio de milheto e crotalária (50%) e pousio (testemunha). As espécies foram semeadas após a colheita do milho safra com 0,45 m de espaçamento entre linhas em blocos ao acaso com seis repetições. A taxa de cobertura do solo foi analisada aos 30, 45, 60, 75 e 90 dias após a semeadura. A matéria seca foi determinada na plena floração de cada cultura, separada em talos/colmos e folhas e secos a 65ºC. A incidência de plantas espontâneas foi avaliada no momento de plena floração. No período entressafra o milheto, consórcio de milheto + crotalária, mucuna-cinza e feijão-de-porco apresentam maior eficiência de cobertura do solo, ambos atingindo 100% de cobertura de solo. Os maiores acúmulos de matéria seca foram do milheto (11.204 kg.ha-1) e consórcio (9291 kg.ha-1). As culturas mais eficientes para a supressão de plantas espontâneas foram o milheto, o consórcio e a mucuna-cinza. A crotalária e trigo-mourisco apresentarambaixo desempenho, logo, não são recomendadas para cultivo solteiro na entressafra milho-trigo.(AU)

The use of cover crops, especially in summer in off-season, is an uncommon practice because they compete with crops of economic importance. The objective was to evaluate the use of cover crops, soil cover and suppression of weeds in the corn-wheat off-season in northwest of Rio Grande do Sul. For this, sunn hemp, gray mucuna, jack bean, lupine, buckwheat, millet, millet, and sunn hemp intercrop (50%) and fallow (control) were used. The species were sown after harvesting the corn crop with 0.45 m spacing between rows in randomized blocks with six replications. The soil cover rate was analyzed at 30, 45, 60, 75 and 90 days after sowing. Dry matter was determined at full flowering of each crop, separated into stalks/stems and leaves, and dried at 65ºC. The incidence of weeds was evaluated at the time of full flowering. In the off-season, millet, millet + crotalaria, gray mucuna and jack bean intercropped have greater soil cover efficiency, both reaching 100% soil cover. The highest accumulations of dry matter were from millet (11,204 kg.ha-1) and intercropped (9291 kg.ha-1). The most efficient crops for the suppression of weeds were pearl millet, intercropped and gray mucuna. Sunn hemp and buckwheat showed low performance; therefore, they are not recommended for single cultivation in the corn-wheat off-season.(AU)

The effect of green fertilizers on the ecological structure of soil invertebrate communities in an andisol of Southwestern Colombia / Efecto de fertilizantes verdes en la estructura ecológica de las comunidades de invertebrados edáficos en un suelo andisol del suroestre de Colombia

Introduction: Chemical fertilizers for agriculture can negatively affect the communities of soil invertebrates that contribute to nutrient cycling, nutrient availability, soil formation and fertility. As an alternative, previous work has suggested that green fertilizers (fresh tissue from plants) are effective to preserve soil fertility, without affecting the ecological properties of invertebrate communities. Objective: This work aimed to evaluate how green fertilizers affect the ecological structure of an invertebrate community in an andisol from Southwestern Colombia. Methods: Fresh leaves from seven plant species locally sown and grown in March 2018 were used as the fertilizers by incorporating and mixing them with the soil in 24 experimental subplots. After 45 days of incorporation, the abundance, richness, biomass and diversity of soil invertebrates were measured in three replicate soil cores per subplot and at three depths. Results: Comparing against a control treatment with no fertilization, the richness and abundance of soil invertebrates were up to 14-fold higher in treatments with Alnus jorullensis and Brassica napus, and up to 5-fold higher in treatments with Vicia sativa, Lupinus mutabilis, Plantago lanceolata and Medicago sativa. Diversity indices showed a shift from high dominance by one or a few invertebrate families in the control treatment, to a high diversity and greater evenness in the A. jorullensis, P. lanceolata and M. sativa treatments. Biomass was negatively correlated with richness and abundance, suggesting a possible ecological trade-off worth to evaluate in further research. Conclusions: In general, our results demonstrate that the application of green fertilizers in this Andean environment can significantly improve the ecological status of soil invertebrate communities. These communities ultimately provide the ecological functions for soil dynamics; thus, agroecology practices should consider them as a valuable alternative to balance production and conservation.

Introducción: Los fertilizantes químicos para la agricultura afectan negativamente a las comunidades de invertebrados, las cuales contribuyen al ciclaje, disponibilidad de los nutrientes y a la formación y fertilidad del suelo. Como alternativa, investigaciones previas han sugerido que los abonos verdes (tejido fresco de plantas) son efectivos para conservar la fertilidad del suelo, posiblemente sin afectar los invertebrados. Objetivo: Evaluar como la aplicación de abonos verdes al suelo afecta cuantitativamente estas propiedades en una comunidad de macrofauna edáfica de un andisol al suroccidente de Colombia. Métodos: El follaje fresco de siete especies de plantas sembradas y cultivadas localmente durante marzo 2018 fue utilizado como abono verde, el cual fue incorporado y mezclado con el suelo superficial en 24 subparcelas experimentales. Después de 45 días de aplicar los abonos, se midió la abundancia, riqueza, biomasa y diversidad de la comunidad de invertebrados. Resultados: En comparación a un tratamiento testigo la riqueza y abundancia de invertebrados fue 14 veces más alta en tratamientos con A. jorullensis y B. napus, y cinco veces más alta en tratamientos con V. sativa, L. mutabilis, P. lanceolata y M. sativa. Los índices de diversidad mostraron un cambio desde una dominancia por una o pocas familias de invertebrados en el testigo, a una alta diversidad y equitatividad en los tratamientos con A. jorullensis, P. lanceolata y M. sativa. La biomasa estuvo correlacionada negativamente con la riqueza y la abundancia, sugiriendo un posible trade-off, en este sentido se sugiere que sea estudiada en futuras investigaciones. Conclusiones: En general, estos resultados demuestran que la aplicación de abonos verdes en estos suelos andinos puede mejorar significativamente la presencia de macroinvertebrados en el suelo.

Influência da adubação verde nas propriedades físicas e biológicas do solo e na produtividade da cultura de soja / Influence of green manure in physical and biological properties of soil and productivity in the culture of soybean

A adubação verde consiste na prática de uso de espécies vegetais em rotação, sucessão ou consorciação com outras culturas comerciais, objetivando melhoria, manutenção e recuperação das propriedades físicas, química se biológicas do solo. Assim, objetivou-se avaliar a influência de diferentes adubos verdes nas características do solo e na produtividade da cultura de soja. O experimento foi realizado em Maringá (PR), em delineamento de blocos casualizados, com seis tratamentos e quatro repetições: T1: aveia branca (Avena Sativa); T2: aveia preta (Avena strigosa), T3: guandu anão (Cajanus cajan), T4: nabo forrageiro (Raphanus sativus L.), T5: tremoço branco (Lupinus albus) e T6: testemunha (pousio). Ao final do experimento foram estabelecidas relações entre o adubo verde utilizado, à produção de soja, à produção de fitomassa, ao desenvolvimento de microrganismos e densidade aparente do solo. Os dados foram analisados em programa estatístico e as médias comparadas pelo teste de Tukey a 5% de probabilidade. As coberturas que propiciaram maior teor de fitomassa foram o tremoço, a aveia preta e feijão guandu. Os tratamentos que mais influenciaram o aumento de microrganismos do solo foram o tremoço, nabo forrageiro e feijão guandu. Em relação à produtividade,maiores valores encontrados foram obtidos nos tratamentos com feijão guandu, tremoço e aveia branca.Quanto à densidade aparente do solo, o tratamento com nabo forrageiro apresentou melhor resultado.

Green manuring is the practice of using plant species in rotation, succession or intercropped with other crops, aiming improvement, maintenance and recovery of physical, chemical and biological soil properties. The objective was to evaluate the influence of different green manures on soil characteristics and productivity of soybean. The experiment was conducted in Maringá (PR) in a randomized block design with six treatments and four replications: T1: oat (Avena Sativa), T2: black oat (Avena strigosa), T3: dwarf pigeon pea (Cajanuscajan), T4: radish (Raphanus sativus L.), T5: white lupine (Lupinus albus) and T6: control (fallow). At the end of the experiment, relations were established between the green manure used for soybean production, the production of biomass, the development of microorganisms and soil bulk density. The data were analyzed with statistical software and means were compared by Tukey test at 5% probability. The coverages provided higher content of dry matter were lupine, black oat and faba bean. Treatments that most influenced the increase of soil microorganisms were lupine, radish and pigeonpea. Regarding productivity, higher values were obtained in treatments with pigeon pea, lupine and oat. The apparent density of the soil, treatment with turnip showed better results.