Assessment of the ecological impact of applying biosolids is important for determining both the risks and bene-
fits. This study investigated the impact on soil physical, chemical and biological properties, tree nutrition and
growth of long-term biosolids applications to a radiata pine (Pinus radiata D. Don) plantation growing on a
Sandy Raw Soil in New Zealand. Biosolids were applied to the trial site every 3 years from tree age 6 to
19 years at three application rates: 0 (Control), 300 (Standard) and 600 (High) kg nitrogen (N) ha−1, equivalent
to 0, 3 and 6 Mg ha−1 of dry biosolids, respectively. Tree nutrition status and growth have been monitored annu-
ally. Soil samples were collected 13 years after the first biosolids application to assess the soil properties and func-
tioning. Both the Standard and High biosolids treatments significantly increased soil (0–50 cm depth) total
carbon (C), N, and phosphorus (P), Olsen P and cation exchange capacity (CEC), reduced soil pH, but had no sig-
nificant effects on soil (0–20 cm depth) physical properties including bulk density, total porosity and unsaturated