Tillage activates iron to prevent soil organic carbon loss following forest conversion to cornfields in tropical acidic red soils

Mingming Zong; Chen Lin; Shiyu Li; Haixia Li; Changqun Duan; Changhui Peng; Yongxing Guo; Ruiqi An

doi:10.1016/j.scitotenv.2020.143253

Tillage activates iron to prevent soil organic carbon loss following forest conversion to cornfields in tropical acidic red soils

Sci Total Environ. 2021 Mar 20:761:143253. doi: 10.1016/j.scitotenv.2020.143253. Epub 2020 Nov 3.

Authors

Mingming Zong¹, Chen Lin¹, Shiyu Li², Haixia Li³, Changqun Duan⁴, Changhui Peng⁵, Yongxing Guo⁶, Ruiqi An¹

Affiliations

¹ School of Ecology and Environmental Science & Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, Yunnan University, Kunming 650091, China.
² School of Ecology and Environmental Science & Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, Yunnan University, Kunming 650091, China; Institute of Environment Sciences, Department of Biology Science, University of Quebec at Montreal, Montreal C3H 3P8, Canada. Electronic address: lisy@ynu.edu.cn.
³ Institute of Environment Sciences, Department of Biology Science, University of Quebec at Montreal, Montreal C3H 3P8, Canada; Faculty of Land Resource Engineering, Kunming University of Science and Technology, Kunming 650093, China. Electronic address: 20030045@kust.edu.cn.
⁴ School of Ecology and Environmental Science & Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, Yunnan University, Kunming 650091, China. Electronic address: chqduan@ynu.edu.
⁵ Institute of Environment Sciences, Department of Biology Science, University of Quebec at Montreal, Montreal C3H 3P8, Canada.
⁶ School of Science, Hangzhou Normal University, Hangzhou 311121, China.

PMID: 33187714
DOI: 10.1016/j.scitotenv.2020.143253

Abstract

Previous studies have shown that deforestation and planting of corn resulted in the loss of soil organic carbon (SOC). However, this is not inevitable in regions with acidic red soil. We selected six cornfields that have been planted for 34 years and adjacent forest plots in southwest China. Using a structural equation model, we identified the SOC contents and 42 soil environmental factors in 11 soil layers that are conducive to SOC storage, and evaluated their relative weights hierarchically (0-40, 40-100, and 100-140 cm). Our results surprisingly indicated that after forest had been converted into cornfield, the SOC density did not change in any layer. In acidic red soil, reactive iron (Fe_o), soil water content, nitrogen, and pH were the main soil environmental factors that affected the storage of SOC. In the 0-40 cm soil layer, compared to forests, the contribution of Fe_o in cornfields increased significantly (by 11.65%), due to farming promoting the activation of iron, while the contribution of nitrogen decreased significantly (by 9.65%). In the 100-140 cm soil layer, the contribution of soil environmental factors was similar to that in the forest system, but the pH in cornfields increasing significantly (by 21.5%) may result from the leaching of hydrogen ions. Although the cultivation of cornfields caused a loss of nitrogen in the 0-40 cm soil layer, the increase in Fe_o promoted combination of iron and soil organic carbon, avoiding the soil layer from SOC loss.

Keywords: Carbon balance; Deep soil; Deforestation; Fe bound organic carbon; Land use change; Maize land.