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| Effect of long-term straw returning and groundwater level on cadmium accumulation and availability in soils |
| Received:April 29, 2020 |
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| KeyWord:straw returning;groundwater level;total cadmium;available cadmium;paddy soil |
| Author Name | Affiliation | E-mail | | WU Jia-qi | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | | | HUANG Yun-xiang | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | yxhuang63@163.com | | YIN Li-chu | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | | | LIANG Yu-wen | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | | | HUANG Ling | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | | | XIANG Yan-yan | Xiangxi Station of Soil and Fertilizer, Jishou 416000, China | | | SHI Qiang | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | |
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| Abstract: |
| This study was carried out to better understand the effects of fertilization methods on Cd accumulation and availability in paddy soil in a long-term experiment that began in 1982. Three fertilization methods were investigated-high amount of straw returning(HS), normal amount of straw returning(MS), and chemical fertilizer(CF)-at two groundwater levels-high water level(-20 cm)and low water level(-80 cm). The results showed that, under high water level, long-term straw returning increased the content of total and available Cd in soils. In comparison to CF treatment, HS and MS treatments increased the content of total and available Cd in soils by 21.8% and 59.9%, and 9.8% and 49.2%, respectively. Under low water level, HS treatment had a higher content of total and available Cd than CF treatment and increased them by 11.2% and 31.6%, respectively. MS treatment had a lower content of total and available Cd than CF treatment and decreased them by 8.8% and 14.3%, respectively. In 2012, given the premise of sufficient repetition of the original positioning test, part of the test treatment under the high water level condition was changed. After 5 years of changing HS treatment to CF treatment, the content of total and available Cd in soil decreased by 2.5% and 5.7%, respectively; CF treatment was then changed to MS treatment, resulting in an increase in the content of total and available Cd in the soil by 16.5% and 58.9%, respectively. Under the same fertilization treatment, the total Cd content in the high water level was higher than that in the low water level condition. MS treatment caused the available Cd content in the high water level to be higher than that in the low water level condition, while HS and CF treatments caused the available Cd content in the low water level to be higher than that in the high water level condition. Correlation analysis of soil Cd content and the basic physical and chemical properties of the soil showed that the total Cd content in the soil had a significant positive correlation with soil organic matter, while complex iron content had a significant negative correlation with pH value. The available Cd in the soil had a significant negative correlation with soil pH value and free iron oxide. Fertilization and water levels affected the accumulation and chemical speciation of Cd in soil by changing the basic properties of the soil. |
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