菜籽饼堆肥对水稻土壤Cd有效性及Cd在水稻全生育期转运与累积的影响

为研究菜籽饼堆肥对土壤Cd有效性和在水稻体内迁移转运与累积的影响,在Cd污染(Cd=0.72 mg/kg)土壤中施用不同添加量(0.75%,1.5%,3.0%)的菜籽饼堆肥,以未添加菜籽饼堆肥为对照(CK),并进行水稻盆栽种植试验。结果表明:(1)菜籽饼堆肥进入稻田土壤后会显著降低土壤中TCLP提取态Cd含量,在熟化期施用0.75%～3.0%的菜籽饼堆肥,与对照相比土壤TCLP提取态Cd含量下降了45.1%～68.7%。但水稻的种植会影响菜籽饼堆肥对土壤中TCLP提取态Cd含量的降低效果,使其含量随着水稻生育期的延长逐渐上升,但仍低于同时期的对照土壤。(2)施用菜籽饼堆肥能显著提高水稻产量,但同时也增加水稻糙米中Cd含量。与对照相比,施用0.75%～3.0%的菜籽饼堆肥,水稻糙米中Cd含量为0.04～0.14 mg/kg,低于国家食品中污染物限量标准(GB 2762—2012, Cd<0.2 mg/kg)。同时,每株水稻产量分别增加3.6～4.3 g/株,约为1 620～1 935 kg/hm^2。(3)施用菜籽饼堆肥会提高Cd在水稻体内的转运能力,同时显著提高水稻成熟期各部位Cd累积量,特别是地上部分。总体来说,施用菜籽饼堆肥增加水稻糙米中Cd含量,但依然保持在较低水平,满足中轻度Cd污染地区水稻的安全生产。但在Cd污染程度更高或者土壤Cd活性更强的土壤中施用菜籽饼堆肥,种植水稻糙米Cd含量可能高于国家食品中污染物限量标准。因此,在保证稻米安全的前提下对Cd污染稻田应该谨慎施用菜籽饼堆肥。

Effects of Rapeseed Cake Compost on Cd Availability in Soil, and Its Translocation and Accumulation in Rice Plant

The effects of rapeseed cake compost (RSC) on Cd availability in soil and its accumulation in different rice tissues were investigated using a pot experiment in this study. In order to provide reference for the safe production of moderately Cd-contaminated fields, RSC was applied to a Cd contaminated paddy soils (Cd=0.72 mg/kg) with different rates of 0, 0.75%, 1.5%, and 3.0% respectively, and then rice plants (Xiangwanxian 12#) were cultivated. The results showed that:(1) The application of RSC resulted in a sharp decrease in the soil TCLP-extractable Cd concentration. Compared with CK treatment, the soil TCLP-extractable Cd concentrations decreased by 45.1%~68.7% after 0.75%~3.0% RSC application. However, the soil TCLP-extractable Cd concentrations in the amended soil gradually increased during the rice growing period. (2) RSC was an effective organic fertilizer for increasing rice yield, but the total Cd concentrations in rice grain were also increased. Compared with CK treatment, when the 0.75%~3.0% RSC was applied, the total Cd concentrations in rice grain were 0.04~0.14 mg/kg, which met the national limit of Cd in food (GB 2762-2012, Cd<0.2 mg/kg). The rice yield was increased by 3.6~4.3 g/pant, 1 620~1 935 kg/hm² approximately. (3) The application of RSC increased Cd transport from root to shoot and significant raised the amount of Cd accumulated in rice plant, especially in the aerial part. In general, in the present study, the application of RSC increased the total Cd concentrations in rice grain. And it still remained at a low level, could meet the safety production of rice in Cd moderately pollution area. However, if RSC was applied to soil with higher Cd pollution level or higher Cd bioavailability, the total Cd concentrations in rice grain might be higher than the national limit of Cd in food. Therefore, we suggested that the application of RSC should be more prudent for the Cd-contaminated fields for the premise of ensuring rice safety production.