Efecto del contenido de Carbono en sustancias húmicas en suelo en un cultivo de cebolla

Le résumé fourni par la source

Carbon (C) contents of humic substances (HS) in soil aggregates are a sensitive indicator of changes in the edaphic quality caused by soil management systems and/or cover plant species.The aim of this study was to assess total contents of C and HS of organic matter in soil aggregates cultivated with onion under a no-till vegetable production system (NTVS) and conventional tillage (CT) compared to a secondary forest area.Treatments consisted of single and mixed cover crops and onion under NTVS: spontaneous vegetation, 100% black oat; 100% rye; 100% oilseed radish; consortium of oilseed radish (14%) + rye (86%); consortium of oilseed radish (14%) + black oat (86%).An area cultivated with onion under CT (± 37 years) and a forest area (secondary forest; ± 30 years) were also evaluated.Five years after implementation of NTVS, undisturbed soil specimens were collected from the 0.0-0.05,0.05-0.10 and 0.10-0.20 m layers and aggregates were obtained (8.00 mm > Ø ≥ 2.0 mm).In these aggregates, total organic carbon (TOC) and C of HS were determined, subdividided into a fulvic acid fraction (C-FAF), humic acid fraction (C-HAF) and humin (C-HUM).With the C values of the HS the following ratios were calculated: C-HAF/C-FAF and (C-HAF+C-FAF)/C-HUM.The highest content of TOC, C-FAF, C-HAF and C-HUM were found in the forest.In NTVS, the contents of TOC (at the 0.0-0.05m depth) and C-HUM (0.0-0.05 and 0.05-0.10m) were higher than those found under CT.The highest C-FAF contents were found under CT.NTVS compared to CT favors the humification process (higher C-HUM content and lower ratios of C-HAF+C-FAF/C-HUM (at the 0.0-0.05 and 0.05-0.10m depths) and the protection of organic matter (higher TOC contents at the 0.0-0.05m depth)).A linear relationship was observed between C-HUM and N of HS.Among the cover plant species, rye alone and rye combined with oilseed radish had the best results regarding humification of organic matter with predominance of C-HUM and C-HAF.This pattern was also observed in the control for C-HUM, due to the abundance of plant families and species, indicating that plant biodiversification is an effective way to improve the quality of soil.

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