title: Effects of soil acidification and liming on the phytoavailability of cadmium in paddy soils of central subtropical China.
abstract: Intensive and paired soil and rice grain survey and multiple-field liming experiments were conducted to assess soil acidification in the past 30 years, quantify the relationships of Cd phytoavailability with soil acidity, and determine efficacies of liming on soil acidity and Cd phytoavailability in paddy soils of central subtropical China at a regional scale. Soil pH, total and extractable Cd (Cdtotand Cdext), rice grain Cd were determined, and all measured data were analyzed separately in groups of 0.1 pH units intervals. Paddy soil pH averagely declined at 0.031 unit yr-1between 1980s and 2014 (P < 0.01). Piecewise means of log Cd transfer ratio kept around -0.062 between soil pH 4.0 and 5.5 and around -1.31 between pH 6.9 and 7.3, whereas linearly decreased by a factor of 0.76 with pH 5.5-6.9, and by a factor of 1.38 with pH 7.3-8.2 (P < 0.01), respectively. Similar responses to soil pH were observed for soil Cdextto Cdtotratio. However, the former exhibited a lag effect to soil acidification in the acidic soils and a leading effect in alkaline soils. Liming increased soil pH by 0.50 units, and decreased rice grain Cd by 35.3% and log Cd transfer ratio by a factor of 0.76 (P < 0.01). The piecewise relationship based on the survey precisely predicted the changes in Cd transfer ratio across the multiple-field liming experiments. In conclusion, soil acidification occurred and accelerated in the past 30 years, and piecewise-linearly increased Cd phytoavailability of paddy soils in central subtropical China. Mitigating soil acidification, i.e. liming, should be preferentially implemented to minimize Cd phytoavailability.
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, PR China.
authors: Hanhua
authors: H
authors: Zhu
authors: Hunan Agricultural Resources & Environment Protection Station, Changsha 410005, PR China; College of Resource & Environment, Hunan Agricultural University, Changsha 410128, PR China.
authors: Cheng
authors: C
authors: Chen
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, PR China.
authors: Chao
authors: C
authors: Xu
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, PR China. Electronic address: qhzhu@isa.ac.cn.
authors: Qihong
authors: Q
authors: Zhu
authors: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, PR China.
authors: Daoyou
authors: D
authors: Huang
mesh_terms: D000143:Acids / Q000009:adverse effects* / Q000737:chemistry; D001682:Biological Availability; D002104:Cadmium / Q000009:adverse effects / Q000032:analysis / Q000378:metabolism*; D017610:Calcium Compounds / Q000009:adverse effects* / Q000737:chemistry; D002681:China; D004787:Environmental Pollution / Q000009:adverse effects*; D005506:Food Contamination / Q000517:prevention & control / Q000706:statistics & numerical data*; D006863:Hydrogen-Ion Concentration; D012275:Oryza / Q000187:drug effects* / Q000378:metabolism*; D010087:Oxides / Q000009:adverse effects* / Q000737:chemistry; D012987:Soil / Q000737:chemistry*
chemical_list: D000143:Acids; D017610:Calcium Compounds; D010087:Oxides; D012987:Soil; D002104:Cadmium; C016538:lime
keywords: Cadmium; Liming; Paddy soil; Phytoavailability; Soil acidification