Research report from OSU's North Willamette Agricultural Research and Extension Center
Delbert Hemphill and V. Van Volk
OSU Dept of Horticulture, NWREC
Chrome tanneries in the United States produce more than 150,000 dry metric tons of solid wastes each year. These wastes consist of hide trimmings, hair, fat, lime, dyes, and heavy metals, particularly Cr. The high N and lime content of the wastes indicate that utilization as a crop fertilizer might be a suitable disposal method. However, high soil concentrations of Cr are toxic to several crops. Tannery waste plots were established at the North Willamette Station in June 1978. Further waste applications were made to the same plots in 1979. Crops of beans and sweet corn were grown on the plots in 1978 and 1979.
To measure residual availability of tannery waste N, the same plots were planted to lettuce and broccoli in 1980. Methods and yield results for these crops were reported in "Vegetable Research at the North Willamette Agricultural Experiment Station, 1979-1980" (Special Report 611, April 1981, Oregon State University Agricultural Experiment Station). This report deals mainly with related soil and plant tissue analyses completed in 1981.
Results and Discussion
Tannery waste application increased soil pH by as much as 1.3 units in the plow layer and 0.9 units at 16-30 cm depth. Soil electroconductivity was also significantly increased by waste treatment but the conductivity was not high enough to affect germination or seedling growth. Waste application increased soil total N, N03-N, NH4-N, B, Ca, and Ni content, decreased extractable P, Mg, and Fe concentrations slightly, and had very little effect on extractable K, Zn, Mn, Cu, S, Pb, Cd, and Mo levels. Soil total Cr levels increased as much as four-fold with application of high rates of tannery waste.
Application of tannery waste had no effect on lettuce or broccoli leaf concentrations of P, K, Ca, Mg, and Fe. Total N levels in the two crops did increase on waste-amended soils but were in the normal range for all treatments. In agreement with soil analysis, waste application had no consistent effect on Zn, Cu, or Mn concentrations of lettuce or broccoli leaves or heads. Plant tissue Ni concentrations were always below the 0.3 mg/kg detection limit. Broccoli and lettuce Cr concentrations were not affected by waste treatments. This confirms results obtained for bush beans and sweet corn in 1978 and 1979.
Increased yields, comparable to those obtained with commercial N fertilizers, and increased tissue N levels occurred when lettuce and broccoli were grown on residual tannery waste plots, indicating that significant quantities of available N were mineralized from waste organic N. There was no movement of Cr through the soil profile, but some movement of N03-N to at least 90 cm depth was noted. Application of chrome tannery waste to cropland may be a feasible disposal alternative with little risk to crops if the waste is applied in amounts providing agronomically suitable amounts of available N. Soil pH, metal content, and movement of Cr and N03 should be closely monitored.