Mill wastewater and olive pomace compost as amendments for rye-grass

A two-year experiment was carried out to study the effects of applying untreated Olive Wastewater (OWW), treated OWW and olive pomace compost as soil amendments on both rye-grass growth and soil characteristics. We analysed growth parameters (Leaf Area Index, and fresh and dry weight), leaf green colour (SPAD readings), N uptake of the rye-grass and chemical soil characteristics. The results indicate that the highest untreated OWW application increased growth parameters by 18.2% in 2001 and by 41.1% in 2002, indicating the possible use of OWW as an amendment to rye-grass. We observed a significant increase in total, extracted and humified organic carbon, and humification parameters. No accumulations of heavy metals in the soil were observed. Furthermore, the N content in OWW was used by the rye-grass for plant growth that increases N uptake, and consequently, dry matter accumulation.