Effect of de-inking paper sludge compost application on soil chemical and biological properties

A 2-yr field study evaluated the effect of applying compost of deinking pap er residues and poultry manure (DSPC) on the chemical and biological proper ties of Tilly silt loam (Gleyed Humo-Ferric Podzol) in Sainte-Croix de Lotb iniere, Quebec, Canada. The experiment began in 1996 with snap bean (Phaseo lus vulgaris L. 'Centralia') and continued in 1997 on the same plots with p otato (Solarium tuberosum L. 'Gold Rush'). In 1996, treatments included thr ee rates of mineral fertilizer (MF) (60, 120 and 180 kg P2O5-K2O ha(-1)), t hree rates of DSPC (14, 28 and 42 Mg ha(-1) on a dry matter basis) alone or in combination with MF, and an untreated control. In the spring of 1997, m ain plots were divided into four subplots and P fertilizer was applied at 0 , 44, 88 and 132 kg ha(-1). The DSPC increased soil pH and water content. S oil inorganic N increased just after DSPC application, but this effect last ed only 1 yr. Soil Mehlich-3 extractable P showed a significant increase du e to DSPC application and the increase was much larger when DSPC was applie d in combination with P fertilizer. Soil phosphatase and urease activities were also increased by DSPC. Application of DSPC increased soil Mehlich-3 e xtractable K and Mg contents. Except for Mn and Zn, soil Mehlich-3 extracta ble heavy metal contents were not influenced by DSPC. This experiment indic ates that compost derived from a mixture of de-inking papermill sludges and poultry manure is a potential source of nutrients for crops and can effect ively improve chemical and biological properties of low fertility or degrad ed soils.