02607naa a2200289 a 450000100080000000500110000800800410001910000180006024501900007826000090026852017530027765300160203065300160204665300180206265300230208065300250210370000130212870000150214170000140215670000200217070000140219070000170220470000200222170000180224170000170225977300410227611290782019-11-04       2018    bl uuuu     u00u1 u    #d1 aSANTOS, L. H.  aCarbon and nitrogen content in granulometric fractions of organic matter in soil aggregates under no-tillage and conventional tillage planting systems for onions.h[electronic resource]  c2018  aCarbon (C) and nitrogen (N) content in granulometric fractions of soil organic matter (SOM) are sensitive indicators of soil quality changes caused by management systems. This study evaluated the C and N content in granulometric fractions of SOM of aggregates, an Inceptisol under onion grown in no-till vegetable farming systems (NTVFS) and conventional tillage systems (CTS), comparing them to a secondary forest. Treatments consisted of soil cover crops, monocropped and intercropped with onions grown under NTVFS: spontaneous vegetation, 100% black oats; 100% rye; 100% oilseed radish; oilseed (14%) + rye (86%) intercrop and oilseed (14%) + oats (86%) intercrop. The same evaluations were also performed in an area with onions grown under CTS for ± 37 years, and in secondary forest (± 30 years). Undeformed soil samples were collected from 0-5, 5-10, and 10-20 cm deep soil layers, and aggregates were subsequently separated (8.00 mm &gt Ø ≥ 2.0 mm). Organic C (OC) and N of the granulometric fractions contents were quantified in aggregates, which were subdivided into particulate fractions (POC and PN) and mineral-associated fractions (OCam and Nam). NTVFS promoted protection of SOM at the 0-5 cm depth compared to CTS, as a result of higher POC content. Intercropped oats+oilseed and spontaneous vegetation contributed to an increase in PN content compared to all other treatments under NTVFS. Monocropped and intercroppped oilseed radish caused an increase in Nam, which was more effective than OCam to indicate differences among the systems. Conversion of areas from CTS to NTVFS promotes increases in POC and PN content in the upper soil layer. NTVFS improves the quality of aggregates, and it may reduce damage caused by CTS  aAllium cepa  aCover crops  aintercropping  aparticulate carbon  aparticulate nitrogen1 aLOSS, A.1 aCANTON, L.1 aSOUZA, M.1 aFERREIRA, G. W.1 aKURTZ, C.1 aBRUNETTO, G.1 aLOURENZI, C. R.1 aLOVATO, P. E.1 aCOMIN, J. J.  tIDESIA , Chilegv. 36, p. 1-9, 2018.