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

Abstract

A 2-yr field study evaluated the effect of applying compost of de-inking paper residues and poultry manure (DSPC) on the chemical and biological properties of Tilly silt loam (Gleyed Humo-Ferric Podzol) in Sainte-Croix de Lotbinière, Qué bec, Canada. The experiment began in 1996 with snap bean ( Phaseolus vulgaris L. ‘Centralia’) and continued in 1997 on the same plots with potato ( Solanum tuberosum L. ‘Gold Rush’). In 1996, treatments included three rates of mineral fertilizer (MF) (60, 120 and 180 kg P2O5-K2O ha-1), three 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, main 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. Soil inorganic N increased just after DSPC application, but this effect lasted only 1 yr. Soil Mehlich-3 extractable P showed a significant increase due to DSPC application and the increase was much larger when DSPC was applied in combination with P fertilizer. Soil phosphatase and urease activities were also increased by DSPC. Application of DSPC increased soil Mehlich-3 extractable K and Mg contents. Except for Mn and Zn, soil Mehlich-3 extractable heavy metal contents were not influenced by DSPC. This experiment indicates that compost derived from a mixture of de-inking papermill sludges and poultry manure is a potential source of nutrients for crops and can effectively improve chemical and biological properties of low fertility or degraded soils. Key Words: De-inking sludge, paper biosolids, poultry manure, phosphorus, potassium, enzyme activity