Soil Respiration of Paddy Soils Were Stimulated by Semiconductor Minerals

Yinping Bai; Ling Nan; Qing Wang; Weiqi Wang; Jiangbo Hai; Xiaoya Yu; Qin Cao; Jing Huang; Rongping Zhang; Yunwei Han; Min Yang; Gang Yang

doi:10.3389/fpls.2022.941144

Soil Respiration of Paddy Soils Were Stimulated by Semiconductor Minerals

Front Plant Sci. 2022 Jun 27:13:941144. doi: 10.3389/fpls.2022.941144. eCollection 2022.

Authors

Yinping Bai^{1

2}, Ling Nan³, Qing Wang², Weiqi Wang⁴, Jiangbo Hai⁵, Xiaoya Yu⁶, Qin Cao², Jing Huang², Rongping Zhang², Yunwei Han¹, Min Yang¹, Gang Yang²

Affiliations

¹ School of Environment and Resource, Southwest University of Science and Technology, Mianyang, China.
² School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, China.
³ School of Resources and Environmental Engineering, Tianshui Normal University, Tianshui, China.
⁴ Key Laboratory of Humid Subtropical Eco-geographical Process, Ministry of Education, Fujian Normal University, Fuzhou, China.
⁵ College of Agronomy, Northwest A&F University, Yangling, China.
⁶ School of Tourism and Resources Environment, Qiannan Normal University for Nationalities, Duyun, China.

Abstract

Large quantities of semiconductor minerals on soil surfaces have a sensitive photoelectric response. These semiconductor minerals generate photo-electrons and photo-hole pairs that can stimulate soil oxidation-reduction reactions when exposed to sunlight. We speculated that the photocatalysis of semiconductor minerals would affect soil carbon cycles. As the main component of the carbon cycle, soil respiration from paddy soil is often ignored. Five rice cropping areas in China were chosen for soil sampling. Semiconductor minerals were measured, and three main semiconductor minerals including hematile, rutile, and manganosite were identified in the paddy soils. The identified semiconductor minerals consisted of iron, manganese, and titanium oxides. Content of Fe₂O₃, TiO₂, and MnO in the sampled soil was between 4.21-14%, 0.91-2.72%, and 0.02-0.22%, respectively. Most abundant semiconductor mineral was found in the DBDJ rice cropping area in Jilin province, with the highest content of Fe₂O₃ of 14%. Soils from the five main rice cropping areas were also identified as having strong photoelectric response characteristics. The highest photoelectric response was found in the DBDJ rice cropping area in Jilin province with a maximum photocurrent density of 0.48 μA/cm². Soil respiration was monitored under both dark and light (3,000 lux light density) conditions. Soil respiration rates in the five regions were (from highest to lowest): DBDJ > XNDJ > XBDJ > HZSJ > HNSJ. Soil respiration was positively correlated with semiconductor mineral content, and soil respiration was higher under the light treatment than the dark treatment in every rice cropping area. This result suggested that soil respiration was stimulated by semiconductor mineral photocatalysis. This analysis provided indirect evidence of the effect semiconductor mineral photocatalysis has on the carbon cycle within paddy soils, while exploring carbon conversion mechanisms that could provide a new perspective on the soil carbon cycle.

Keywords: photocatalysis; rice cropped area; semiconductor minerals; soil carbon; soil respiration.