Evaluating spoil amendment use and mycorrhizal inoculation on reforestation success in the eastern and western kentucky coalfields

A factorial experiment using inoculated vs. non-inoculated forest species in non-fertilized, fertilized only, amended (organic mulch) only, and fertilized + amended plots was established in 2004 on two mined lands in the Eastern (EKY) and Western (WKY) Kentucky coalfields. Fifty-four 15 × 15 meter plots were delineated on each site. Half of the plots received an application of 40 tons per acre of a wood chip/manure compost mixture. All plots were subsequently ripped to a depth of approximately 2-meters using a dozer. Two tree species; Loblolly Pine (LP) (Pinus taeda) and Northern Red Oak (NRO) (Quercus rubra), were planted in the plots. Each plot received 100 seedlings spaced at 1.5 meter centers. The mycorrhizal trees were inoculated with Pisolithus tinctorius (Pt) and Scleroderma cepa (Sc) in the nursery beds. Additional spores were applied in the field after they were transplanted. The non-mycorrihizal plots received an application of fungicide on an annual basis (Bayleton; 1 kg per plot) to suppress natural inoculation. Fertilized plots received 150 pounds of 20-20-20 fertilizer per acre (168 kg per ha) on an annual basis. Each treatment was examined in triplicate for each species. Ripping of the sites reduced in-situ bulk density at both locations. Application and incorporation of the compost resulted in a further decrease in bulk density both at the surface and through the entire 30.5-cm depth examined. Although the effect was similar between the two sites, the WKY site exhibited a higher final bulk density than that observed in EKY. After four years, growth and survival of planted seedlings differed with respect to species, site and treatments. LP exhibited almost a doubling in growth at the EKY mine as compared to the WKY mine. Amendments had no effect on LP growth at the WKY site. All amendments had a positive effect on LP growth over that of the control in the EKY site. Use of compost and mycorrhizal fungi yielded the highest survival for LP at both sites. NRO growth was very low compared to LP and did not differ drastically between the two sites. Treatment effects were observed on both sites and results varied. Compost and fertilizer without mycorrhizae exhibited the highest NRO survival at both sites. Fertilizer addition improved NRO survival at the EKY mine and the use of compost without fertilizer appeared to increase mortality. The use of compost with mycorrhizae may have also had an inhibitory effect on NRO survival in WKY, or fungicide application may have provided a positive effect at this site. Herbaceous biomass was much higher on the EKY mine, but no correlations between herbaceous biomass and tree growth or survival were observed for either site.