Research report from OSU's North Willamette Agricultural Research and Extension Center
Delbert Hemphill and V. Van Volk
OSU Dept of Horticulture, NWREC
Tannery waste plots were established at the North Willamette Experiment Station in June 1978. Further applications of tannery wastes were made to the same plots in 1979. Crops of beans, corn, and tall fescue were grown on the plots in 1978 and 1979. To measure the residual availability of tannery waste nitrogen, the same plots were planted to broccoli and lettuce in 1980. The fescue plots were maintained and harvest of clippings was continued without addition of more waste.
Methods
Broccoli
Broccoli cultivar 'Waltham 29' was direct seeded on June 11 with between-row spacing of 20 inches, six rows per 10 foot x 20 foot plot, four replicates in randomized block design. Trifluralin at 0.75 pounds/acre and fonofos at 1.0 pounds/acre were incorporated before planting. Treatments consisted of unfertilized control, 328' pounds/plot of waste applied in 1978 and again in 1979, 656 pounds waste applied in 1978 and 1979, 1312 pounds waste applied in 1978 only, 656 pounds waste and 50 pounds/acre of commercial N applied in 1978 and 1979, and 100 pounds/acre of N applied at planting in 1980. Stands were thinned to 18 inch in-row spacing. Leaf samples were collected at the seven leaf stage. Plots were harvested once at maturity of the main head on September 12.
Lettuce
Lettuce cultivar 'Ithaca' was direct seeded on June 19 on 20-inch between-row spacing. Pronamide was applied at 2.0 pounds/acre immediately after planting. Treatments were check, 219, and 438 pounds of waste applied per 10 x 20 foot plot in both 1978 and 1979; 875 pounds of waste applied in 1979 only, 438 pounds waste and 50 pounds/acre of commercial N in 1978 and 1979, and 100 pounds/ acre of nitrogen applied in 1980. Stands were thinned to 12 inches between plants. Leaf samples were collected at harvest on August 14.
Fescue
Plots established in 1978 and 1979 were kept weed free with one application of 2,4-D and dicamba. Leaf samples were collected at first and last harvests of the 1979 plots. Treatments were check, 164 pounds waste per 7.5x15 foot plot, 328 pounds, 656 pounds, 160 pounds/acre of N applied in 1979 only, and 160 pounds/acre of N applied in 1980 to plots established in 1979.
Results
Broccoli
Plants from plots receiving the intermediate rate of waste in 1978 and 1979 and the plots receiving commercial N in 1980 yielded significantly more than plants from check plots and were not significantly different from each other. Thus, a significant amount of N was made available to the broccoli crop by a previous waste application. Treatments had no effect on plant stand or tendency to flower prematurely.
Lettuce
Treatments had no effect on stand establishment or number of heads harvested. Lettuce on all waste and commercial N treated plots yielded more than lettuce on check plots. As with broccoli, residual N from the waste was-sufficient to produce a good crop.
Fescue
Plots were harvested four times in 1980. Significant differences were obtained at each cutting.
Yields from plots treated with the intermediate or high level of waste in 1978 significantly exceeded those from check plots and were proportional to the amount of waste applied. Thus, even after two years, the residual tannery waste was providing significant N for crop growth. Yields from plots treated with waste in 1979 were significantly greater than check plot yields and yields were proportional to amount of waste applied. Yield from plots treated with the highest rate of waste did not differ significantly from the yield of plots receiving 160 pounds/acre of commercial nitrogen in 1980.
Tannery waste appears to be a very effective fertilizer for grass crops and the effect of a single application lasts for at least two years. Use of tannery waste as a fertilizer for food chain crops will not only depend on its efficacy as a fertilizer, but will also depend on demonstration that its use does not result in potentially toxic heavy metal accumulation in the crop. Previous results indicated little increase in metal content of beans and corn grown on tannery waste-amended soil.