EFFECTS OF LIME AND FERTILIZER AMENDMENTS ON PLANT-GROWTH IN SMELTER IMPACTED SOILS IN MONTANA

A greenhouse study was conducted in 1995 to determine shoot and root b iomass and shoot concentrations of trace elements in bluebunch wheatgr ass [Agropyron spicatum (Pursch)Scribn.] grown in soils impacted by co pper smelting that extended for a period of 96 years. Soils from two s eparate sites, ranging from 2 to 8 km from the smelter, were used in t he study along with soil from the same area that was nor impacted by s melting activities. Soils from the two impacted sites were amended wit h lime, fertilizer, or lime + fertilizer or were nor treated with any amendments (control) to determine the effect of lime and fertilizer on plant growth, shoot concentrations of trace elements, and plant avail ability of trace elements in the soil. Following a 13-week growth peri od, bluebunch wheatgrass growing on unamended smelter impacted soils h ad reduced amounts of shoot and root biomass compared to the control s oil, but the differences were not significant. An increase in shoot an d root biomass resulted from the application of fertilizer or lime to the impacted soils, but the increases were not significant. The additi on of nitrogen, phosphorus, and potassium resulted in a greater increa se in shoot and root biomass than the application of lime alone. Plant growth in the soil from the site closest to the smelter was reduced c ompared to the plant growth measured on the control soil or the soil t aken from the impacted site 8 km from the smelter. The only two trace elements with concentrations in plant shoots that exceeded established phytotoxic levels for agricultural plants were copper and zinc. The t issue concentrations of these elements, however, fell within the low e nd of the phytotoxicity range for moderately sensitive agricultural pl ants, and the concentrations were therefore not considered to represen t a toxicity problem for the native perennial species evaluated in thi s study. Overall, the application of lime reduced plant-available trac e element concentrations in the soil and trace element concentrations measured in shoot material.