RESUMO
Applications of deinking paper sludge (DPS) decreased the establishment of some crops, indicating that it may have inhibiting effects. The effects of soil-applied DPS on total carbon (C), nitrogen (N), C:N ratio, and nitrate, ammonium, and phenolic compounds were studied for 2 years. The phytotoxicity of simulated phenolic solutions of raw DPS and DPS-amended soil was investigated. Twelve phenolic compounds were quantified in raw DPS. Vanillin and 3-hydroxy-4-methoxycinnamic acids increased with DPS applications in amended soil for both years. Total soil C and the C:N ratio increased with DPS applications, while nitrate soil content decreased. Germination indices were affected differently by the phenolic compound solution that simulated DPS. This study highlights the lack of availability of nitrate as the main factor involved in the inhibiting effect of DPS. However, other inhibiting effects of phenolic compounds cannot be ruled out since they are known to inhibit nitrification and to trap nitrate into organic N compounds.
