施用磷肥对南方酸性红壤镉生物有效性及土壤酶活性影响

Effects of phosphorous fertilizers on Cd bioavailability and soil enzyme activities in south acidic red soil

采用盆栽试验,研究了普钙和钙镁磷肥对油菜生物量和Cd含量、土壤p H值和Cd有效态含量以及土壤酶活性的影响.结果表明,施加普钙和钙镁磷肥后,油菜生物量分别比对照处理增加41.8%—60.5%和90.2%—171.6%,油菜地上部Cd含量分别降低达54.3%—86.7%和74.4%—79.6%,其中当普钙和钙镁磷肥施加量为中高剂量时,油菜地上部Cd含量降低至0.18 mg·kg-1和0.10 mg·kg-1,符合国家食品安全标准《食品中污染物限量》(GB 2762—2012)规定的叶菜蔬菜中Cd的最大限量值.施加普钙和钙镁磷肥均降低了土壤中Cd有效态,与对照相比,土壤中HCl提取态Cd含量分别降低0.9%—21.2%和33.8%—43.9%,CMP处理下TCLP(Toxicity characteristic leaching procedure,TCLP)提取态Cd含量降低33.0%—43.0%.施加高剂量普钙和中剂量钙镁磷肥时,土壤过氧化氢酶活性与对照相比分别增加了202.5%和52.6%,施加不同剂量的普钙均显著降低土壤脲酶活性,降低率达28.2%—65.9%,而添加普钙和钙镁磷肥对蔗糖酶活性均无显著性影响.土壤p H与油菜生物量以及土壤脲酶成极显著正相关关系,与TCLP-Cd成显著负相关关系.油菜生物量与土壤有效态Cd含量和油菜体内Cd含量存在负相关关系,其中与HCl提取态Cd及地上部Cd含量存在显著负相关关系.

Pot experiments were conducted to investigate the effects of the two phosphate fertilizers（ SSP,CMP） on the rape biomass and Cd content,soil p H and available Cd,and soil enzyme activities. The results showed that the rape biomass increased by 41. 8%—60. 5% and 90. 2%—171.6%,respectively compared with the control groups after the application of the two fertilizers. Incontrast,the available Cd content decreased by 54. 3%—86. 7% and 74. 4%—79.6%,and the Cd concentration in the shoots decreased to 0.18 and 0.10 mg·kg-1,which met the national food safety standards ＂the limits of contaminants in food＂（ GB 2762—2005）,the maximum limits of Cd in the leaves and vegetables when the treatments of SSP was up to middle and high concentration. The soil available Cd showed a certain degree of reduction with the addition of SSP and CMP. Compared with no-phosphate treated soil,HCl-Cd concentrations decreased by 0.9%—21.2% and 33.8%—43.9%,respectively,under the application of SSP and CMP,and the contents of TCLP-Cd in soils suffered33.0%—43. 0% reduction after applying CMP. Under the treatments of higher level of SSP and medium level of CMP,the activity of catalase increased by 2. 0% and 52. 6%,respectively. The urease activity significantly decreased, resulting in 28. 2%—65. 9% reduction under different concentrations of SSP,while there were no significantly difference in invertase activity under the addition of SSP and CMP. Soil p H was significantly positively correlated with the rape biomass and soil urease,but significantly negatively with the concentration of TCLP-Cd. Rape biomass was negative with soil available Cd and the Cd uptake by rape.