不同改良剂对微碱性土壤镉形态及小麦吸收的影响

研究过磷酸钙、石灰和硅钙镁肥单一施用对土壤Cd形态和小麦植株不同器官Cd含量的影响，以期为微碱性Cd污染土壤安全利用提供理论参考.通过盆栽试验，研究不同改良剂对小麦成熟期土壤Cd形态以及二乙基三胺五乙酸（DTPA）提取态镉含量的影响，分析小麦不同器官中Cd的含量.结果表明：过磷酸钙显著降低了土壤的pH值，石灰和硅钙镁肥显著提高了土壤的pH值.3种改良剂均可以显著降低土壤DTPA提取态镉含量，其中施用硅钙镁肥（3%）的效果最好，降幅为73.60%.添加硅钙镁肥可显著降低土壤可交换态镉含量，同时增加残渣态镉含量，其中硅钙镁肥（3%）处理效果最佳，土壤可交换态镉含量降幅为63.30%，残渣态镉含量增幅为56.20%.3种改良剂均可显著降低小麦地上部、地下部Cd含量，其中硅钙镁肥处理对小麦地上部及地下部Cd含量降低效果最佳.硅钙镁肥（1.2%）处理对小麦籽粒镉含量降低效果最好，降幅为90.85%.土壤pH值与土壤DTPA提取态Cd含量达到了极负显著水平，土壤DTPA提取态Cd含量与小麦各器官中Cd呈极显著正相关.因此，施用不同改良剂可不同程度的降低土壤中Cd的生物有效性和小麦植株不同器官中Cd的含量，缓解Cd对植株的胁迫效应. 3种改良剂在同等剂量水平下，硅钙镁肥对小麦器官中镉的降低效果最佳.

Effects of different amendments on chemical speciation and uptake by winter wheat in slightly alkaline soil contaminated by Cadmium

The effects of a single application of three amendments (superphosphate, lime, and silicon-calcium-magnesium fertilizer) on chemical speciation of cadmium in soils and the uptake of cadmium in different organs of wheat plants were studied to provide a theoretical reference for the safe utilization of Cd contaminated slightly alkaline soils. Pot experiments were conducted to investigate the fraction transformation of soil Cd and cadmium content of the extracted state of diethylene triamine pentaacetic acid (DTPA) in the mature stage of wheat. The results showed that superphosphate significantly decreased soil pH, while lime and silicon-calcium- magnesium fertilizer increased soil pH. All three amendments could significantly reduce soil cadmium content of the extracted state of diethylene triamine pentaacetic acid (DTPA), and the biggest decline (73.60%) occurred in the silicon-calcium-magnesium (3%) fertilizer treatment. The treatment of adding silicon-calcium-magnesium fertilizer could significantly reduce the exchangeable Cd and increase the residual Cd content. The treatment of silicon-calcium-magnesium fertilizer (3%) had the best effect of the decrease of soil exchangeable Cd content by 63.30% and the increase of residual Cd content by 56.20%. All three amendments effectively reduced the content of Cd in above-ground and below-ground parts of wheat plants, while the treatment of silicon-calcium- magnesium fertilizer had the best effect. The treatment of silicon-calcium-magnesium fertilizer (1.2%) had the best effect of the decrease of Cd content in wheat grains by 90.85%. An extremely negative and significant correlation was found between soil pH value and soil cadmium content of DTPA, while Cd content of soil DTPA extract state was positively correlated with Cd content in wheat organs. Therefore, the application of three amendments (superphosphate, lime, and silicon-calcium-magnesium fertilizer) could reduce the bioavailability of Cd in soil and Cd content in different organs of wheat plants to various degrees, and alleviate the stress effect of Cd toxic action on plants. With the same dose, silicon-calcium-magnesium fertilizer had the best effect on reducing cadmium content in wheat organs among three amendments.