Effect Of Fertilizer Application On Soil Heavy Mental Phytoremediation By Sedum Alfredii Hance

As one of the most important measures of traditional agronomic management practice, fertilization to cropland is to improve soil nutrient status and to promote nutrient uptake by plant, so that to achieve high-yield and high-quality output. Fertilization could be also used to enhance heavy metal removal in phytoremediation of soils contaminated with heavy metals through its promotion to plant growth and increase of heavy metal absorption. In addition, through the interaction of fertilizers with soil heavy metals, fertilization can affect soil adsorption - desorption of heavy metals, change the forms of heavy metals in soils, and change heavy metal activity in the soils.Consequently, heavy metal absorption and accumulation of plants is influenced. Sedum alfredii Hance has been identified as a zinc (Zn) and cadmium (Cd) hyperaccumulator native to China. It has characteristics of large biomass, fast growth and easy propagation. It is a good material for phytoremediation and study of phytoremediation mechanism. The objectives of this thesis are to enhance the phytoremediation efficiency of heavy metal contaminated soils by Sedum alfredii Hance through fertilization practice. Efficacy of nitrogen (N), phosphorus (P) or potassium (K) fertilizers and organic manure on phytoremediation of Zn and Cd by Sedum alfredii Hance were examined by a series of pot experiments. The results indicated that increase of heavy metal accumulation in Sedum alfredii Hance could be achieved by appropriate fertilization management. For N application, plant of Sedum alfredii Hance requires low level of N to increase Zn and Cd uptake. When high rate of N was applied the growth of Sedum alfredii Hance was restrained, and heavy metal accumulation in the plant declined. Growth of plant dry matter of Sedum alfredii Hance increased remarkably with P application, and uptake and transport of Zn and Cd from roots to shoots of Sedum alfredii Hance were effectively improved as well in the range from 0.1 to 0.4 mmol P/L in the solution culture experiment. However, higher P supply reduced Zn and Cd accumulation and the transport from the roots to the shoots. Effect of K on the biomass of Sedum alfredii Hance was significant but the effect of K on Zn and Cd accumulation of Sedum alfredii Hance was not minimal. Organic manure greatly significantly biomass growth and Zn and Cd accumulation of Sedum alfredii Hance. Integrated fertilization of inorganic fertilizers of N, P and K in combination with organic manure revealed the best treatment to improve soil Zn and Cd phytoremediation by Sedum alfredii Hance.