Phosphorus: a limiting factor for restoration of soil fertility in a newly reclaimed coal mined site in Xuzhou, China

Massive exploration of coal in China has resulted in a significant loss of agricultural land throughout the country. To relieve this increasing shortage, reclamation of abandoned coal mine areas has been prioritized. This study aims to identify the limiting factor(s) affecting the restoration of the soil fertility in a coal-mined area. The work was carried out in a typical area, the Xuzhou coalfield in northern Jiangsu province. Soil fertility parameters showed that the tested soil was very poor, especially in phosphorus. By using soil-pot experiments, it was demonstrated that application of nitrogen and potassium, but without phosphorus fertilizers, did not result in increase in crop yields, while the rational application of organic and inorganic fertilizers improves soil fertility significantly as shown by yields of rice, wheat and green vegetables. By comparing the effectiveness of different treatments, soil phosphorus was identified as the limiting factor in restoring the fertility of this newly reclaimed land. Study on the soil phosphorus speciation further revealed that Ca2-P was the main source of variation in the supplying capacity of soil phosphorus, whereas Ca10-P remained unchanged.