Seasonal variation in the availability of plant nutrients in acid colliery spoil.
The pH, percentage moisture, and temperature of colliery spoil, and the K, Ca, Mg, Na, Fe, Zn, Cu, Mn and Al concentration of saturation paste extracts of the spoil, were measured at frequent intervals for 2 years. Extractable Al, Mn, Cu, Zn and Fe were greater in the spoil in summer and autumn, whereas extractable K and pH were lower at these times. Addition of limestone significantly increased pH and reduced extractable Al, Mn and Zn. It also reduced extractable Zn, Fe and Cu, and increased Ca, though these effects were not significant. Neither shoddy nor sewage sludge had any significant effect on any of the attributes measured, or on the seasonal pattern of variation. Wide seasonal and diurnal variations in temperature were recorded at 1 cm depth and also, to a lesser extent, at greater depths in the spoil.