ABSTRACT
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.
ABSTRACT
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.