02076naa a2200265 a 450000100080000000500110000800800410001910000210006024500960008126000090017752013440018665000160153065000240154665000160157065000170158670000170160370000220162070000200164270000160166270000180167870000140169670000180171070000240172877300580175211360072025-10-16       2025    bl uuuu     u00u1 u    #d1 aBORTOLINI, J. G.  aSoil microbial activity in a long-term organic no-till onion system.h[electronic resource]  c2025  aSoil biological attributes are sensitive to management practices, and can be indicators of soil quality, especially in long-term sustainable areas. This study has been conducted in an area with organic no-till onion production for eight years in Ituporanga, southern Brazil. The experiment has a randomized block design with six replications and treatments are: fallow (natural weeds), rye (RY), oilseed radish (OR), or RY+ OR consortium, in winter, followed by onion in spring and velvet bean in summer, besides an area with onion in a conventional system (CS) as the control. Dry mass cover crops, activity fuorescein diacetate hydrolysis (FDA), soil basal respiration (SBR), metabolic quotient (qCO2), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) were evaluated at 0, 58, 80, and 99 days after cover crops sowing (DAS), and 40 and 99 days after onion transplanting (DAP). The cover crops had higher mass than the fallow treatment. FDA was 182% higher in the NTVS than in the CS. MBC at 80 DAS was 88% higher in the NTVS compared to the CS, while MBN at 58 DAS was 63% higher in NTVS compared to the CS area. In addition, CS had higher SBR and qCO2 contents due to the system disturbance. The organic no-till onion system promotes soil health in the long term by increasing biological activity compared to the CS.  aAllium cepa  aBiological activity  aCover crops  aSoil quality1 aCOMIN, J. J.1 aGIOVANETTI, L. K.1 aVENTURAS, B. S.1 aALMEIDA, J.1 aMORAIS, G. P.1 aKURTZ, C.1 aLOVATO, P. E.1 aSOARES, C. R. F. S.  tOrganic Agriculture, Berlingv. 15, p. 245-257, 2025.