MINERALIZATION AND VOLATILE LOSS OF NITROGEN FROM SOILS TREATED WITH COAL COMBUSTION BY-PRODUCTS

There is an increasing need to find a suitable means for disposal of c oal combustion byproducts because of the increasing world-wide product ion of these byproducts. This need has prompted interest in the use of land disposal, but there are concerns that this use may degrade the q uality of soil. To determine the influence of coal combustion byproduc ts on the transformation and fate of soil N and assess the potential i mpact of land disposal on soil quality, we studied the effects of two combustion byproducts (fly ash and bed ash) applied at rates of 22.5, 45, 90, and 180 Mg ha-1 on mineralization and volatile loss of N from soil. Studies comparing the influence of the byproducts on these proce sses showed that whereas fly ash had little influence on the fate of s oil N, bed ash caused substantial mineralization of organic soil N and volatile loss of this N as NH3. Studies monitoring the pH of soils tr eated with bed ash showed that soil pH increased immediately after thi s treatment, with values reaching as high as 12.8. These studies indic ated that such extreme alkaline conditions caused chemical degradation and volatile loss of as much as 10% of the organic N in soil, and the y provide strong evidence that the improper disposal of bed ash on lan d can have a substantial negative impact on soil quality.