Influence of steam-treated grass clippings on grass growth, drainage water quality and soil microbial properties in a simulated golf course

Abstract The effects of steam-treated (hydrolytic process using high temperature 207°C and high pressure steam 1.6 MPaG for 30 min) grass clippings and their liquid residue on growth, drainage water quality and soil microbial properties were evaluated. Soils were placed in plastic containers (47 cm length × 40 cm width × 22.5 cm depth) so that the surface (0–10 cm depth) was a mixture of Andisol and sand (3:2 volume) and the subsurface soil (10–20 cm depth) was Andisol only. A basal dose of chemical fertilizer (25 g m−2 NPK 8–8–8) and poultry manure (20 g m−2) was applied. The treatments were: CF (without incorporation of plant residues and 25 g m−2 NPK 8–8–8 top dressing 1 month after transplanting), LL (1 kg m−2 commercial leaf litter), GT (1 kg m−2 steam-treated grass clippings), GT + BL (1 kg m−2 steam-treated grass clippings plus 6 L m−2 liquid residue in a single application as basal fertilizer), GT + FL (1 kg m−2 steam-treated grass clippings plus 3.2 L m−2 liquid residue diluted 10-fold and applie...