Modifications of the phosphorus cycle with development of lignite mine soils

Various aspects of the P cycle in four and seven year old soils from the Meirama lignite mine (northwest Spain) were studied. With increasing soil age, The organic P (P_o) content increased in parallel with the organic matter content. the observed increase in secondary inorganic P (Bic—P_i + NaOH-P_i + us-NaOH P_i) is related to the increase in the retention capacity for P with soil age. the observed increase in the HCl-P fraction can be attributed to a gradual dissolution of the non-extractable forms of P produced from fertilizers added in the course of spoil management. Both the C:P_o ratio and phosphatase activity also increased with soil age, suggesting that biochemical mineralization processes are taking place and indicating a need for the hydrolysis of phosphate esters to ensure an adequate phosphorus supply to plants. All these findings suggest that in the long term plants May, suffer a pronounced P deficiency.