Relationship between soil inorganic carbon and organic carbon in the wheat-maize cropland of the North China Plain

Fractions of soil organic and inorganic carbon and their relationships in typical loess cropland of Fenggu Basin

“…Our study showed that SIC was signi cantly lower in LFB (9.2-10.6 g kg -1 ) than in YCB (11.4-13.4 g kg -1 ) above 80 cm, which corresponded with signi cantly higher DIC:SIC ratio in the LFB (0.91%) than in the YCB (0.39%) in the topsoil (Table 2). There were some studies on SIC dynamics in the croplands of north China that have the same or similar parent materials, such as in the Loess Plateau (Zhang et al 2015) and the North China Plain (Guo et al 2016, Shi et al 2017b. Clearly, SIC content in the LFB (with redeposited topsoil) is much lower than that in the western highland (>15 g kg -1 ) of Loess Plateau (Zhang et al 2015) that has much drier climate and higher soil pH (Table 3).…”

“…There are some studies addressing SIC-SOC relationship, which report inconsistent ndings. While there is evidence of a positive correlation between SIC and SOC stocks in the cropland of north China (Guo et al 2016, Shi et al 2017b, Wang et al 2015b, studies also report a negative SIC-SOC relationship under various land uses in the north China (Li et al 2010, Zhao et al 2016. In particular, Zhao et al (2016) found that SOC had a negative relationship with SIC under mixed land uses (i.e., forest, grass, shrub lands) in the Loess Plateau that undergoes profound erosion.…”

“…For instance, there is evidence that high soil pH often leads to low levels of SOC but high levels of SIC (Oste et al 2002, Tavakkoli et al 2015, Wang et al 2015a. Recent studies suggest that hydrologic process may have in uences on various fractions of soil carbon, including dissolved organic (DOC) and inorganic carbon (DIC) that result from the desorption of organic matter and the dissolution of inorganic carbon, respectively (Shi et al 2017b, Zhang et al 2020. There is evidence that higher levels of CaCO 3 or Ca 2+ /Mg 2+ are bene cial for SOC stabilization (Tavakkoli et al 2015, Virto et al 2011 because of enhanced formation of soil aggregates (Rowley et al 2018).…”

“…There is a distinctive difference in vertical distribution between SOC and SIC in the north China's cropland: i.e., a sharp decrease in SOC but a general increase in SIC with depth (Shi et al 2017b, Zhang et al 2015. Erosion and redeposition of topsoil from highlands to lowlands could have in uences on the storages of both SOC and SIC, thus altering the SOC-SIC relationship in the Loess Plateau.…”

Organic and inorganic carbon and their stable isotopes in surface sediments of the Yellow River Estuary

“…Recent studies have showed that there was a large amount of carbonate in the soils of lower part of the Yellow River Basin, and higher level of carbonate was associated with high level of organic carbon (Guo et al, 2016;Shi et al, 2017). One may expect a similar phenomenon in the sediment of the Yellow River Estuary.…”