Conversion of coastal marshes to croplands decreases organic carbon but increases inorganic carbon in saline soils

Yuanshan Zhu, Yidong Wang, Changcheng Guo, Dongmei Xue, Jun Li, Qing Chen, Zhaoliang Song, Yilai Lou, Yakov Kuzyakov, Zhong Liang Wang, Davey L. Jones

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


Over the past century, conversion to agriculture has greatly reduced the global extent of coastal wetlands leading to degradation and loss of these ecosystems. However, it remains unclear how this land conversion affects the confluent soil organic and inorganic carbon (SOC and SIC) storage as well as their localizations in soil matrix. Here, we investigated these issues using wet sieving at two coastal saline–alkali sites in northern China. Conversion of marshes to cropland (>60 years) decreased the portion of large macroaggregates (>2 mm) and correspondingly increased the portion of microaggregates (0.053–0.25 mm) at both sites. Land conversion decreased SOC contents by 31–67% in all fractions (>2, 0.25–2, 0.053–0.25, and <0.053 mm) in the topsoil (0–15 cm) and subsoil (15–30 cm). In contrast, irrigation- and NH4HCO3 fertilization-derived carbonates increased SIC storages in almost all fractions due to the saline–alkali soil conditions, especially for the subsoil. This increases in SIC almost offset and compensate for the SOC losses at both sites. Consequently, the irrigation- and NH4HCO3-induced SIC accumulation should be included in the full C balance of saline–alkali soils. It should be noted, however, that the progressive loss of SOC due to cultivation will lead to soil degradation in fertility and ecological function, thereby hampering long-term sustainability of coastal ecosystems. Therefore, the compensation of SIC for the loss of SOC is not sustainable in the longer term.

Original languageEnglish
Pages (from-to)1099-1109
Number of pages11
JournalLand Degradation and Development
Issue number9
Publication statusPublished - 30 May 2020


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