富镉基质中紫花苜蓿的生长与利用研究

Study on growth and utilization of alfalfa grown in Cd-rich substrate

在采煤沉陷地缺乏土壤资源的情况下充填复垦,寻求来源丰富、养分含量高的复垦基质与适种作物成为土地复垦的研究热点。试验将粉煤灰与污泥(基质1)、粉煤灰与酒糟(基质2)各以5∶1的质量比混合,粉煤灰与糠醛渣(基质3)以9∶1的质量比混合制成基质,进行紫花苜蓿Medicago sativa的基质栽培试验。结果表明,第1年由于基质中盐分、重金属镉含量过高造成紫花苜蓿产量偏低,紫花苜蓿干样中重金属镉的含量超出饲料卫生标准,但是紫花苜蓿鲜样中重金属镉的含量不超标,可以为牲畜提供新鲜饲料,也可压青肥田。基质经过1年的淋洗与植物吸收后,基质中盐分含量降至正常水平,基质中镉含量虽然降至土壤环境质量二级标准以上,但苜蓿产量达到了正常土壤中的产量水平,苜蓿干样中镉的含量已达到饲料卫生标准,且营养成分含量丰富,可用于生产优质干饲料。适宜废弃地的大面积复垦与推广应用,为改善矿区生态环境提供了新的途径。

The improvement of coal mining subsidence land by finding the proper substrates with riclnutrition and suitable soil properties for crop has become the research focus at the case of soil become the scarce resource. Three substrate formulas, including fly ash ＋ sewage sludge （substrate 1）, fly ash ＋ lees （substrate 2） and fly ash ＋ furfural residue （substrate 3）, were used to study the effect on alfalfa cultivation. The results showed that the alfalfa yield was low and the dry matter based Ce content in alfalfa was over the health standard in the first year due to the high contents of salt and Cd, however, it could be used as fresh fodder for livestock or green manure. Due to the plant absorptior and leaching in the first year of, the content of salt in the substrates declined to the normal level ant the alfalfa yield achieved the normal level, the Cd content in substrates reduced to 4 to 6 times of environmental quality standards, and the dry matter based Cd content in alfalfa reached the health standard.