Different Impacts of Early and Late Rice Straw Incorporation on Cadmium Bioavailability and Accumulation in Double-Cropping Rice

Zhong Hu, Qian Qi, Yuhui Zeng, Yuling Liu, Xiao Deng, Yang Yang, Qingru Zeng, Shijing Zhang () and Si Luo ()
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Zhong Hu: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Qian Qi: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Yuhui Zeng: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Yuling Liu: Hunan Cultivated Land and Agricultural Eco-Environment Institute, Hunan Academy of Agricultural Science (HAAS), Changsha 410125, China
Xiao Deng: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Yang Yang: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Qingru Zeng: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Shijing Zhang: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China
Si Luo: College of Environment and Ecology, Hunan Agricultural University, Changsha 410128, China

Sustainability, 2025, vol. 17, issue 17, 1-20

Abstract: Straw return is widely adopted to promote agricultural sustainability, but it can also increase cadmium (Cd) bioavailability in contaminated paddy soils, potentially leading to higher Cd accumulation in rice grains. Although numerous studies have investigated straw incorporation, the specific differences between early- and late-season straw return regarding Cd dynamics within double-cropping rice systems remain inadequately characterized. To address this knowledge gap, we conducted a two-year field experiment comparing early-rice (ER) and late-rice (LR) straw return, complemented by controlled pot experiments simulating ER (ER-S, ER-CK; July–September 2023) and LR (LR-S, LR-CK; December 2022–March 2023) straw incorporation. The results revealed that the Total-Cd exhibited an upward trend following both ER and LR straw incorporation. The ER treatment caused a rapid yet short-lived increase in CaCl 2 -extractable Cd (CaCl 2 -Cd) concentration, peaking around 60 days following straw return and exhibiting a 28.83% increase compared to the LR treatment. In contrast, the LR treatment induced a slower but more prolonged Cd release, with CaCl 2 -Cd concentration peaking around 210 days and exhibiting a 34.89% increase relative to the ER treatment. Additionally, at the late-rice stage, grain Cd concentration in the ER treatment increased by 23.64% relative to the LR treatment. In the subsequent year, grain Cd concentrations in the LR treatment increased significantly by 32.12% to 45.08% compared to the ER treatment for both early- and late-rice crops. These differences were attributed to variations in straw decomposition rates, soil pH, and redox potential between warm, aerobic summer–autumn conditions and cooler, anaerobic winter–spring conditions. This suggests that returning late-rice straw constitutes an elevated hazard to soil health and rice safety compared to early-rice straw return.

Keywords: rice straw; cadmium; bioavailability; double-cropping rice (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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