EFFECTS ON CHEMICAL SURFACE-PROPERTIES OF TUFF BY GROWING ROSE PLANTS

The desorption and solubilization characteristics of scoria tuff, a vo lcanic material used as growth substrate under protected environments and in the open fields were determined following two years of rose gro wing, and compared with uncropped fertigated tuff and with original, u nfertigated tuff. Rose growing in the tuff increased the tuff's water- soluble P, Ca and Mg concentrations and decreased the Al and Si concen trations, compared with plantless and intact tuff sources. It is sugge sted that these changes stemmed from accumulation of soluble organic c ompounds exuded by roots or released from decomposing dead roots in th e cultivated tuff.