A Comparison of Turfgrass Response to Biologically Amended Fertilizers

Abstract

Initial release of N from waste materials used as natural organic N carriers for turfgrass may be slow due to the need for microbial degradation. In a greenhouse study, `Rebel' tall fescue (Festucau arundinacea Schreb.) and `Tifway' bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] growth response to a natural organic fertilizer (Turf Restore) amended or not amended with a soil-derived microbiological inoculum were compared with soluble urea using sterilized and nonsterilized soil. No interactions of soil sterilization and fertilizers were noted at 19 days after treatment (DAT). Urea fertilizer increased tall fescue growth rates by 68% in the nonsterilized soil and 126% in the sterilized soil compared to rates for turf grown with inoculated Turf Restore. Nitrogen uptake rate was 419% higher with urea-fertilized turf in the sterilized soil than for turf fertilized with inoculated Turf Restore. Soil sterilization at 33 DAT no longer affected turf response, but turf growth rate was 133% higher and N uptake 353% higher with urea fertilization than with inoculated Turf Restore. Infection of the plants with Rhizoctonia spp. at 72 DAT was unaffected by fertilizer treatments. Bermudagrass response was similar to that of tall fescue. Growth rate was 67% and N uptake 51% higher with urea than with Turf Restore through 17 DAT, regardless of inoculant addition. Amendment of the natural organic fertilizer Turf Restore with a soil-derived biological inoculant did not enhance turf growth rate or N uptake nor impact infection with Rhizoctonia spp.