organic matter, total nitrogen and mineral enrichment in the soil.
Twelve months after sludge application, the C:N ratio was
significantly lower in the Ts level of the 30S and 60S plants,
whereas no changes appeared in the Bs level. This decrease was
primarily due to the high nitrogen supply in the sludge. In fact, the
upper soil layers were enriched in total nitrogen by up to 1.8 times
for 30S and 2.1 times for 60S. Since the Bs layer remained
unchanged we can conclude that after one year of culturing no
downward leaching occurred. Similar results have been presented
by Egiarte et al. (2005) and Mañas et al. (2010).