Response of corn and fescue to land application of industrial waste arising from illmenite ore processing

Industrial sludge, a by-product of Ti extraction from illmenite ore (FeTiO₃), was applied to corn and fescue plots at rates of 0, 22, 45, and 90 metric tons/ha. Each rate of sludge, which characteristically has a pH value <2, was applied at two rates of lime, 9 and 18 metric tons/ha, except for the 0 rate which was maintained as a control. The application of the waste material and lime did not affect the yield of either corn or fescue.

Tissue samples were taken at three stages of growth from each species and analyzed for selected heavy metals. Concentrations of As, Cd, Fe, Na, Ni, Pb, Se, Ti, and Zn in the first and second harvests of fescue were not affected by any treatment. Manganese concentrations in the fescue samples were significantly increased as a result of the rate of sludge. The concentrations ranged from 183 to 358 yg/g of tissue in the first harvest, and from 231 to 410 yg/g in the third harvest. The Ni concentration in the second harvest was significantly increased by applying sludge at the rate of 22 metric tons/ha while the 90 metric tons/ha rate increased in Ni concentration in the third harvest.

Manganese concentration in the corn fodder and grain stages were not affected by any treatment. However, corn ear-leaf analysis gave a significant increase in Mn as a result of treatment with 22 metric tons/ha sludge with 18 metric tons/ha lime. Concentration of Cd, Na, Fe, and Zn showed considerable variation among the stages of growth. Titanium in both species was not influenced by the treatments.

Soil water samples were collected at four depths in both corn and fescue plots (30, 61, 92, and 122 cm). Analysis of soil water samples indicated that the conductivity, chloride concentration, and Ni content increased due to the 90 metric ton sludge application. The pH of the groundwater, however, was not decreased by the applied treatments.

Analysis of the soil from each treatment showed no tendency for the pH, CEC, and organic matter being altered by the sludge-lime treatments. Heavy metal analysis indicated a tendency for the concentration of Mn and Fe to be increased in the 0—15 cm layer while Ni concentrations increased in the subsurface layers.