A particular wormcasting (vermicompost from biological sludges) and sewage water (from a municipal sewage plant) have been employed in an ecological strategy for the conservation of arable soils. A soil sampled in the south of Italy (Matera), seeded with Avena sativa was used in experiments on: (1) direct incorporation of vermicompost into the soil (VC treatment) and (2) fertirrigation with sewage waters mixed with humic substances extracted from vermicompost (IH treatment). The soil biochemical activities (dehydrogenase and BAA-protease) were higher under IH treatment in which the humic substances stimulated soil metabolic activity. Ar the end of the experiments (one month) a phyto-test (with Lepidium sativum) was carried out on the treated soils; a growth index (GI%) was calculated. A positive correlation (p <0.05) between chemical and biochemical parameters was found meaning that soil productivity was affected by mineral nutrients derived from organic matter mineralisation. (C) 1997 Elsevier Science Ltd.