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| Effects of different long-term tillage methods and straw returning on cadmium bioavailability in paddy fields |
| Received:February 04, 2021 |
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| KeyWord:tillage methods;straw returning;double cropping rice;cadmium;bioavailability |
| Author Name | Affiliation | E-mail | | LONG Zedong | Institute of Soil and Fertilizer, Hunan Academy of Agricultural Sciences, Changsha, 410125 China | | | SUN Mei | Institute of Soil and Fertilizer, Hunan Academy of Agricultural Sciences, Changsha, 410125 China | | | LUO Zunchang | Institute of Soil and Fertilizer, Hunan Academy of Agricultural Sciences, Changsha, 410125 China | | | SUN Geng | Institute of Soil and Fertilizer, Hunan Academy of Agricultural Sciences, Changsha, 410125 China | sungeng@hunaas.cn | | LI Chao | Institute of Soil and Fertilizer, Hunan Academy of Agricultural Sciences, Changsha, 410125 China | | | XIAO Xiaoping | Institute of Soil and Fertilizer, Hunan Academy of Agricultural Sciences, Changsha, 410125 China | |
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| Abstract: |
| The effects of different tillage methods and straw returning on the bioavailability of cadmium in a soil-rice system in Hunan Province were studied with the aim to provide supporting data for improved soil quality and reduced rice cadmium content in these systems. The trial was randomized and a total of four treatment groups were designed:plow tillage with residue removed(CT); plow tillage with residue retention(CTS); rotary tillage with residue retention(RTS); no-tillage with residue retention(NTS). The study found that the NTS group increased the soil CEC content and reduced the proportion of powder particles. The total cadmium and ion-exchanged cadmium contents in NTS soil were(0.48±0.01) mg·kg-1 and(0.39±0.01) mg·kg-1, respectively. These were not significantly different from the CTS and RTS treatments but were significantly higher than the CT treatments. The total cadmium content of brown rice from early and late rice in NTS were(0.30±0.04) mg·kg-1 and(0.60±0.07) mg·kg-1, respectively, which exceeded the national food safety standards(0.20 mg· kg-1) and were significantly higher than in the other treatment groups. The total cadmium content in brown rice was positively correlated with total soil cadmium, carbonate bound cadmium, and iron-manganese bound cadmium. The weaker the tillage intensity, the higher the bioavailability of cadmium in soil, and the higher the bioavailability of cadmium in straw returning to the field compared with the nonreturn treatment. Tillage methods and straw returning affect the cadmium content in rice by affecting soil bioavailable cadmium. No-tillage with straw returning to the field increases the cadmium content in soil and brown rice, resulting in unsafe cadmium levels that exceed the national food safety standards. |
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