Abstract

RODRIGUEZ, Silvia et al. Hot-water extractable carbon as indicator of southeastern Buenos Aires province mollisol's health. Cienc. suelo [online]. 2020, vol.38, n.1, pp.149-161. ISSN 1850-2067.

Sustainable agriculture requires early soil health indicators (ISE). Some easily measurable variables, as hot-water extractable carbon (CAC), are needed to monitor soil health status frequently. The aim of this study was to evaluate CAC as an ISE. We explored: i) the magnitude of the changes in CAC, total organic carbon (TOC), and particulate organic carbon (POC) due to cropping, and ii) the relationship between CAC, POC, TOC, and ammonium nitrogen mineralized in anaerobiosis (NAN) with aggregate stability. Soil samples (0-5 and 5-20 cm) from 32 production fields (LP) and pseudo-pristine situations (SP) from Southeastern Buenos Aires province were analyzed for: bulk density (DA), change of mean weight aggregate diameter (CDMP), TOC, POC, NAN, and CAC. At 0-20 cm depth, CAC ranged between 0.69 and 1.41 g kg^-1 for LP and between 0.75 and 2.36 g kg^-1 for SP. Hot-water extractable carbon represented 3.23% and 3.57% of TOC for LP and SP, respectively. Hot-water extractable carbon was negatively related to DA and CDMP, and positively related to TOC or POC expressed as stock related to an equivalent mass (TOC_ME and POC_ME), and to NAN. Under LP CAC dropped 35% respect to SP, whereas POC_ME and TOC_ME decreased 62% and 25%, respectively. The CAC could be used as an ISE, given it was sensitive to the changes produced by cropping and it related to some other soil properties that indicate soil health status. Its determination is simple, fast, and cheap, which favors its adoption by commercial soil testing laboratories.

Keywords : particulate organic carbon; aggregate stability; mineralizable nitrogen.

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