Cover cropping promotes soil carbon sequestration by enhancing microaggregate-protected and mineral-associated carbon

Shaoqing Zhu; Upendra M Sainju; Shaohong Zhang; Guangye Tan; Mengmeng Wen; Ying Dou; Ruijia Yang; Jinfa Chen; Fazhu Zhao; Jun Wang

doi:10.1016/j.scitotenv.2023.168330

Cover cropping promotes soil carbon sequestration by enhancing microaggregate-protected and mineral-associated carbon

Sci Total Environ. 2024 Jan 15:908:168330. doi: 10.1016/j.scitotenv.2023.168330. Epub 2023 Nov 4.

Authors

Affiliations

¹ Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, College of Urban and Environmental Science, Northwest University, Xi'an 710127, China; Shaanxi Key Laboratory for Carbon Neutral Technology, Northwest University, Xi'an 710127, China.
² USDA-ARS, Northern Plains Agricultural Research Laboratory, 1500 North Central Avenue, Sidney, MT 59270, USA.
³ College of Chemistry and Chemical Engineering, Dezhou University, Dezhou 253023, China.
⁴ Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, College of Urban and Environmental Science, Northwest University, Xi'an 710127, China; Shaanxi Key Laboratory for Carbon Neutral Technology, Northwest University, Xi'an 710127, China. Electronic address: wangj@nwu.edu.cn.

PMID: 37931820
DOI: 10.1016/j.scitotenv.2023.168330

Abstract

Cover cropping can improve soil C sequestration compared to no cover cropping, but the mechanism of C sequestration in soil aggregates and minerals needs more exploration. We explored C sequestration using C fractions in soil aggregates and minerals by cover crops in a five-year old summer cover crop - winter wheat (Triticum aestivum L.) rotation system at Changwu National Agroecology Experimental Station in the Chinese Loess Plateau. Three cover crops as soybean (Glycine max L., SB), sudangrass (Sorghum sudanense (Piper) Stapf, SG), soybean and sudangrass mixture (SS) were planted during summer fallow and incorporated into the soil two weeks prior to wheat planting each year. Soil samples at 0-10, 10-20, and 20-40 cm depths were collected at wheat harvest after 5-yr and analyzed for C fractions which were coarse particulate organic C (cPOC), intra-microaggregate fine particulate organic C (iPOC), free fine particulate organic C (fPOC), and mineral-associated organic C (MOC). The iPOC and MOC are considered as protected C against mineralization. Compared to no cover crop (CK), cover crops increased large macroaggregate proportion at 0-10 cm by 18-22 %, with SS having a greater mean-weight diameter (MWD) than other treatments. Cover crops had greater MOC, iPOC, and fPOC fractions than CK in most aggregate-size classes and the bulk soil at all depths, with SS having the greatest C fractions. The MOC was greater than any other C fractions, regardless of cover crop species. Cover cropping can enhance soil aggregation and C sequestration by increasing microaggregate-protected and mineral-associated C compared to no cover cropping, resulting in improved soil C stabilization. Cover crop mixture was more effective in promoting soil aggregate stability and C fractions than single cover crop species.

Keywords: Aggregate-protected carbon; Carbon fractions; Carbon sequestration; Cover crop; Soil aggregation.