Response of soil microbial communities to agroecological versus conventional systems of extensive agriculture

CHAVARRIA, DIEGO N.; PÉREZ-BRANDAN, CAROLINA; SERRI, DANNAE L.; MERILES, JOSÉ M.; RESTOVICH, SILVINA B.; ANDRIULO, ADRIAN E.; JACQUELIN, LUIS; VARGAS-GIL, SILVINA

AGRICULTURE, ECOSYSTEMS AND ENVIRONMENT

ELSEVIER SCIENCE BV

Año: 2018 vol. 264 p. 1 - 8

0167-8809

World population growth has led to a rise in resource demands imposed on agricultural systems, generating anincreased global use of natural resources. However, agroecology proposes self-regulation in order to achieve asustainable agricultural balance. Therefore, considering the rapid responses of microbial communities to smallchanges in soil use, the objective of this study was to assess the response of soil microbial communities to agroecologicalvs. conventional systems of extensive agriculture. Soil sampling was carried out in 2016 and 2017with three different treatments using the sequence soybean/maize (Glycine max L./Zea mays L.) as the maincrop: Agroecological (AE), conventional with cover crops (CC) and conventional without cover crops (control).Species used as cover crops were wheat (Triticum aestivum), vetch (Vicia sativa L.), oat (Avena sativa L.) and radish(Raphanus sativus L.). Agroecological treatment showed the lowest total nitrogen (0.18mgNg⁠−1) and organiccarbon (1.99mgCg⁠−1) content of soil, and CC treatment showed the highest value of fluorescein diacetate hydrolysis,with values 63.2% and 12.1% higher than AE and the control, respectively. However, AE treatment alsoproduced the highest F:B ratio (44.8) and the lowest metabolic quotient (1.14), which indicates an improvementin metabolic efficiency and soil quality. No significant differences were recorded in the abundance of fungal andbacterial communities between treatments. Our results suggest that agroecological management is characterisedby fungal dominance in soil microbial communities and a higher microbial metabolic efficiency compared toconventional management. These results demonstrate more efficient use of carbon substrates in agroecologicalsystems, which could counteract the negative effect of the lack of synthetic fertilisation and reduced-tillage inthe long term. The findings demonstrate that sustainable agricultural tools with adequate management can beeffectively used to preserve soil quality.