RESPONSE OF RYEGRASS TO PHOSPHATE IN THE RECLAMATION OF COAL MINE SOIL

An experiment was conducted to investigate the response of ryegrass to applied phosphate fertilizer in five different coal mine soils from Central Scotland during 1986-88. Different response of ryegrass was observed due to the wide variation in phosphorus supplying power of these soils. These soils also differ in other chemical and biological properties, which might also influence the reaction and availability to added phosphate. Since the other chemical and biological properties had no direct influence on crop response to applied phosphate, it is considered that the initial phosphate level of the soil is the most important factor influencing crop response to added phosphate. Lolium perenne can benefit from the addition of phosphorus in phosphate deficient soils. However, there is a danger that such an increase in phosphorus addition can cause phosphorus losses. This study further showed that all coal mine soils are not deficient in phosphate. Therefore any recommendation of phosphate fertilize for a given area cannot be applied to all coal mine soils. The poor correlation of acetic acid extractable phosphorus with phosphorus uptake and crop yield indicate that either acetic acid is extracting an unavailable pool due to low pH of coal mine soil, or it has limitations in the analysis of soils derived from different parent materials.