The lower labile carbon of surface soils in Chinese semiarid areas

Figures & data

Figure 1. The location of the study area and the research sites from reported literature. (a) the sites location, XA: Xi’an, Chinese Loess Plateau, this study; AUS: Australia (Yao et al. 2019); GER: Germany (Spohn and Giani 2011); SC: South China, Hunan (Wang et al. 2007) and Guangxi (Wang and Wang 2007); SRB: Republic of Serbia (Šeremešić et al. 2013); USA: United States (Rodriguez et al. 2021). The map of mean annual precipitation (MAP) is from the data in https://psl.noaa.gov/. (b), the location of study site and Chinese Loess Plateau. (c), the mean annual temperature and annual precipitation of Xi’an, data are cited from http://data.cma.cn.

Figure 2. The carbon content of the topsoil of the study area. (a) soil organic carbon (SOC) content at 0-5 cm and 5-10 cm, (b) hot water extractable organic carbon (HWOC) content at 0-5 cm and 5-10 cm. The box shows the mean value and ±1σ standard deviation range, and the whisker shows the outlier data.

Table 1. The primary extraction conditions of hot water extractable organic carbon (HWOC).

Site	Location	Soil/water ratio	Temperature	Duration	Author(s)
AUS	Australia	1:5	70 ^oC	18 h	Yao et al. (2019)
GER	Germany	5g:25ml	—	60 min	Spohn and Giani (2011)
GX	Guangxi, China	4g:20ml	70 ^oC	18 h	Wang and Wang (2007)
HN	Hunan, China	20g:100ml	100 ^oC	1 h	Wang et al. (2007)
HN	Hunan, China	1:10	80 ^oC	16 h	Zhang et al. (2009)
SRB	Republic of Serbia	10g:40ml	80 ^oC	16 h	ŠermeŠiĆ et al. (2013)
USA	United States	3g:30ml	80 ^oC	16 h	Rodriguez et al. (2021)
XA	Xi’an, China	50g:200ml	85 ^oC	150 min	This study

Figure 3. Comparison of soil organic carbon (SOC) and hot water extractable organic carbon (HWOC) contents between the study area and literature reports. (a) SOC content of woodland, (b) SOC content of grassland, (c) SOC content of arable land, (d) HWOC content of woodland, (e) HWOC content of grassland, and (f) HWOC content of arable land. P/T is the ratio of annual precipitation to annual average temperature, which represents the corresponding precipitation per degree centigrade. AUS: Australia; GER: Germany; SC: South China, Hunan and Guangxi; SRB: Republic of Serbia; USA: United States; XA: Xi’an, Chinese Loess Plateau. Error bars show 1σ standard deviation. XA, AUS, HN and USA were 0-10 cm, and GX, SRB and GER were 0-20 cm.

Figure 4. Hot water extractable organic carbon (HWOC) content and HWOC proportion. (a) HWOC and soil organic carbon (SOC) contents of the study area in 0-10 cm, (b) HWOC and SOC contents from the literature reports, (c) HWOC proportion of the study area, (d), (e), (f), (g) and (h) HWOC proportion from the literature reports. AUS: Australia; GER: Germany; SC: South China, Hunan and Guangxi; SRB: Republic of Serbia; USA: United States; XA: Xi’an, Chinese Loess Plateau. Error bars show 1σ standard deviation.

Yao L, Rashti MR, Brough DM, Burford MA, Liu W, Liu G, Chen C. 2019. Stoichiometric control on riparian wetland carbon and nutrient dynamics under different land uses. Sci Total Environ. 697:134127.

 PubMed Web of Science ®Google Scholar

Spohn M, Giani L. 2011. Total, hot water extractable, and oxidation-resistant carbon in sandy hydromorphic soils-analysis of a 220-year chronosequence. Plant Soil. 338:183–192.

 Web of Science ®Google Scholar

Wang K, Wang K, Peng N, Lv H, Xie X. 2007. Water extractable carbon in red soil of paddy field. Chin J Soil Sci. 38(3):447–451. in Chinese.

 Google Scholar

Wang QK, Wang SL. 2007. Soil organic matter under different forest types in Southern China. Geoderma. 142:349–356.

 Web of Science ®Google Scholar

Šeremešić S, Milošev D, Sekulić P, Nešić L, Ćirić V. 2013. Total and hot-water extractable carbon relationship in chernozem soil under different cropping systems and land use. J Cent Eur Agric. 14(4):1479–1487. doi:10.5513/JCEA01/14.4.1382.

 Google Scholar

Rodriguez AF, Gerber S, Inglett PW, Tran NT, Long JR, Daroub AH. 2021. Soil carbon characterization in a subtropical drained peatland. Geoderma. 382:114758. doi:10.1016/j.geoderma.2020.114758.

 Web of Science ®Google Scholar

Zhang J, Wang S, Wang Q, Liu Y. 2009. Content and seasonal change in soil labile organic carbon under different forest covers. Chin J Eco-Agric. 17(1):41–47. in Chinese.

 Google Scholar