Physico-chemical properties of reclaimed soil filled with flyash: A case study of Huainan

The test site locates in the subsidence area of Panyi colliery, Huainan city, and flyash used come from Tianji power station. Three different covering thickness test fields are designed, including of 20cm, 30cm and 50cm. Indexes chosen are as follows volume weight, texture, moisture content, pH, organic matter, total nitrogen, available phosphorus and rapidly-available potassium. The variation of soil physical-chemical properties is analyzed. Test results show that, the texture of flyash is silty loam, and the capacity of holding water is good; in addition, the pH of original flyash is strongly alkaline, but the influence to pH of reclaimed soil is unconspicuous after natural weathering in the open environment. Comparing with "soil fertility index classification", more conclusions are as follows: the average level of organic matter in topsoils is Grade II or IH; organic matter in ash layers comes to Grade I; the average level of total nitrogen in topsoils and ash layers get to Grade III or I; the average level of available phosphorus in all layers is Grade El; the average of rapidly-available potassium in all layers comes to Grade I.