SOIL ORGANIC CARBON IN THE CAMPOS DE CIMA DA SERRA REGION (SOUTHERN BRAZIL)
Description
The soil sampling points across the region of interest (KMZ attached) had been established in an earlier research effort on the effects of land-use change and grassland management on vegetation in the Campos de Cima da Serra region described in Leidinger et al. (2017). Our field sampling took place in 2015 and 2016 - using 62 sites from the UFRGS/TUM project. A detailed description of the site selection protocol is presented in Koch et al. (2016). In brief: Soil samples were obtained in dug pits (30 cm wide x 30 cm long x 40 cm depth) in triplicate at each sampling location, matching the smpling scheme of UFRGS/TUM project (Fig.1 in Leidinger et al., 2017): one central point and two additional points spaced by 30 m, aligned with the slope at the site. This sampling spacing was applied to minimize the effect of autocorrelation between the samples obtained and to estimate site variability. Soil samples were collected from the walls at each dug pit with volumetric rings ( = 8cm, 5 cm height), removed from the center of 0-10 and 10-20 and 20-30 cm layers for soil bulk density (SBD) and SOC analysis. At some sites, soils were shallower than 30 cm. << figure 2>> The soil cores obtained were oven dried at 50°C for five days, ground, homogenized and sieved (2 mm mesh). Subsequently, the residual moisture of the samples was determined to report SBD and SOC concentrations on a dry soil basis. Although a Brazilian protocol (Oliveira et al., 2014) suggests collection of separate samples for SBD and SOC, using the same soil sample to obtain SBD and SOC estimates has been adopted in regional studies (Pachompon et al., 2010; Schöning et al., 2013) when a large number of samples are collected to facilitate handling and processing. Moreover, a recent guideline issued by FAO (2019) explicitly recommends that SOC be determined in the same core (SBD sample). Soil organic C was analyzed in a C/N Thermo Flash elemental analyzer using finely ground aliquots from the samples. Soil C stocks were calculated as proposed by Ellert and Bettany (1995): SOC stock = SOC content (kg Mg-1) × layer thickness (m) × soil bulk density (Mg m-3) × 10.
Files
Steps to reproduce
To update SOC stocks and refine SOC distribution (in the form of a SOC map) we used two datasets: a) primary data: soil sampling campaigns followed by laboratory analysis; b) secondary data: compilation of surveys and published studies and yhe most up-to-date soil map of RS