Technique of reclaiming subsided land with Yellow River sediments in the form of spaced strips

Subsidence is one of the most serious ecological and environmental problems in eastern China,and the main purpose of subsided land reclamation in these areas is to restore into farmland. The new technique of reclaiming subsi- ded land with Yellow River sediments in the form of spaced strips was used in Qiuji Coal Mine,Shandong Province. The technique process,reclaimed landscape,soil profiles,soil physical and chemical properties,and productivity were researched. The results shown that 100% of subsided land could be reclaimed,and more than 95. 12% was cultivated land. Water-holding capacity of 60 cm soil covered on the sediment layer of reclaimed farmland was suitable to crops growth,but soil bulk density was higher and porosity was lower than control farmland due to mechanical compaction.Reclaimed farmland had higher pH values and lower EC content than control farmland where was available for crop growth. According to the standard classification of the Second Soil Survey of China,the contents of available nitrogen, available phosphorus and organic matter of soil in reclaimed farmland were in a low level;and the content of available potassium was in a medium level;the content of total nitrogen was in a very low level;and the content of total phos- phorus and total potassium were in a medium-high level. Therefore,the farmland should apply organic and nitrogen fer- tilizer before plant crops. The field investigation showed that the reclaimed and control farmland had the same corn yield. The research showed that the technique of reclaiming subsided land with Yellow River sediments in the form of spaced strips was feasible in a large-scale subsided area,and this case in Qiuji Coal Mine also could be a specific ex- ample for the reclamation of mining subsidence land with Yellow River sediment.