Converting rice paddy to upland fields decreased plant lignin but increased the contribution of microbial residue to SOC

• Published in: Geoderma Vol. 425; p. 116079
• Main Authors: Wang, Quan-Cheng, Wang, Weiqi, Zheng, Yong, Vancov, Tony, Fang, Yunying, Xia, Yun, Liu, Xuyang, Fan, Yuexin, Wei, Zhihua, Yang, Liuming
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2022
• Subjects: Amino sugar; Land-use change; Lignin phenol; Microbial residue; Soil moisture content; Soil organic carbon; Lignin phenol; Soil organic carbon; Land-use change; Soil moisture content; Amino sugar; Microbial residue
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2022.116079

•Conversion of paddy to upland lowered SOC, microbial biomass and nutrient availability.•Contribution of plant lignin phenols to SOC decreased in upland soils.•Microbial residues declined but their relative contribution to SOC increased in upland soils.•Soil moisture determined plant lignin phenols and microbial residues accumulation. Most land-use changes profoundly alter the composition of soil organic carbon (SOC) via changes in plant- and microbial-derived C in soils. Whether this equally holds true for soils converted from paddy fields to upland fields is hitherto unknown. Herein, we investigate and report on plant-derived C (lignin phenols as biomarkers), microbial-derived C (amino sugars as biomarkers), Phospholipid fatty acids (PLFAs), and soil properties following the conversion of rice paddy to upland (vegetable and jasmine) fields in a subtropical farmland ecosystem. Lower moisture, pH, and available nitrogen (AN) but higher temperatures were observed in upland soils compared to paddy soils. Moreover, fungal- and bacterial-PLFAs were 41–63% and 58–69% lower, respectively, in upland soils than in paddy soils. Compared to paddy soils, concentrations of SOC, total lignin phenols (VSC) and amino sugars (TAS) declined in upland soils by 18–46%, 32–70% and 6–31%, respectively. Converting rice paddy fields to vegetable/jasmine cropping fields also altered the composition of SOC; i.e., the contribution of total lignin phenols to SOC declined by 25–48% in the upland soils, while total amino sugars input towards SOC increased by 22–28%. Our findings highlight the ecological risk of carbon loss caused by land-use changes, namely, the conversion of paddy fields to upland field systems.