ADDITION OF PULP MILL ASH RAISES PH, MODIFIES PHYSICAL PROPERTIES, AND ALTERS YOUNG TOMATO PLANT GROWTH AND MINERAL NUTRITION IN A PEAT-BASED SUBSTRATE

Abstract

Pulp and paper mills often burn wood waste to fuel their boilers. The ash from a Mississippi pulp mill boiler was evaluated for potential use as an amendment to peat moss-based greenhouse substrates for production of young tomato plants. Between 0 and 50% ash was added to a custom-blended peat moss-based substrate, and these were compared to a commercially available substrate without ash. Addition of ash increased substrate pH, conductivity (EC), bulk density and water holding capacity, while reducing airspace and average particle size. In general, tomato plants grown in 0–40% ash had similar growth indexes as plants grown in commercial substrate. Increasing amounts of ash decreased tomato shoot nitrogen (N), potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) concentration, and increased concentrations of phosphorus (P), calcium (Ca), sulfur (S), and boron (B). These results indicate that pulp mill ash has the potential to be used as a substrate component for greenhouse container production of tomato.