Effects of Compost Sources and Treatments On Germination and Emergence of Four Turfgrass Species.

Compost is increasingly used as an amendment for enhancing revegetation of disturbed residential soils. The objective of this research was to compare the effects of compost source and management on turfgrass germination and emergence. The study was conducted in greenhouse pots. Eight seeding treatments and 4 turfgrass types were factorially combined, replicated four times, and arranged in a completely randomized design. The seeding treatments were: 1) seed planted on surface of 2.6 cm compost overlying soil, 2) seed planted on soil surface below 0.65 cm compost, 3) seed planted on soil surface below 1.3 cm compost,  4) seed planted on soil surface below 2.6 cm compost, 5) seed planted on 2.6 cm soil surface covered with a straw mat,  6) seed planted below 1.3 cm soil, 7) seed planted below 1.3 cm of compost-amended soil,  and 8) seed planted on soil surface. Tall fescue (Festuca arundinacea), Kentucky bluegrass (Poa pratensis), bermudagrass (Cynodon spp.), and zoysiagrass (Zoysia Spp.) were used as the bioassay crops. Each of 5 studies was conducted, in turn, using a different source of compost. Compost was produced predominantly from five feedstocks – yard waste, food waste, dairy manure, papermill sludge and biosolids. A surface soil from an eroded Piedmont landscape (Appomattox loam: fine, mixed, semiactive, mesic Oxyaquic Hapludults) was used as a container medium at a thickness of 5 cm. 211 tall fescue turfgrass seeds, 469 kentucky bluegrass seeds, 80 bermudagrass seeds and 273 zoysiagrass seeds  were planted per pot. Following application of the seeding treatments, the pots were watered to field capacity. Optimum seed germination soil moisture conditions were maintained by misting the pots 6 times daily throughout the course of the study. Greenhouse temperatures were maintained between 20 (minimum) and 22 (maximum) degrees C. The number of seedlings that germinated and emerged were counted and recorded. The composts were analyzed for total solids, total organic C, total Kjeldahl N, C/N ratio, ammonium and nitrate N, P, K, trace elements, pH, electrical conductivity (EC), porosity, bulk density, water-holding capacity, and Solvita compost maturity tests for ammonia and carbon dioxide evolution. All of the composts were determined to be very stable by means of the Solvita test except for the biosolids compost, which evolved relatively high concentrations of ammonia. The pH ranged from approximately 6.1 (food waste compost) to 9.3 (dairy manure compost). The EC of all composts were below 2.5 dS/m, except for biosolids compost (6.25 dS/m). We will use SAS to calculate mean germination and emergence for each treatment x turfgrass type for each compost source and use the SAS GLM GRCBD procedure to determine statistical effects. Results of analysis of variance between treatments, between turfgrass and between each treatment x turfgrass type were all significant differences (P<0.05).  For the yard waste compost, the treatments that resulted in the highest and lowest germination and emergence, respectively, were T2 (95.7%) and T1 (72.9%) for tall fescue, T1 (74.0%) and T4 (8.3%) for Kentucky bluegrass, T1 (54.1%) and T5 (0.94%) for bermudagrass, and T8 (23.4%) and T4 (1.56%) for zoysiagrass. For the food waste compost, the treatments that resulted in the highest and lowest germination and emergence, respectively, were T1 (91.69%) and T4 (76.4%) for tall fescue, T1 (64.8%) and T4 (1.3%) for Kentucky bluegrass, T8 (70.0%) and T4 (7.2%) for bermudagrass, and T8 (28.1%) and T4 (0.5%) for zoysiagrass. For the dairy manure compost, the treatments that resulted in the highest and lowest germination and emergence, respectively, were T5 (98%) and T7 (69%) for tall fescue, T1 (77%) and T4 (5.7%) for Kentucky bluegrass, T8 (86%) and T4 (5.6%) for bermudagrasss, and T8 (22%) and T4 (0.09%) for  zoysiagrass. For the biosolids compost, the treatments that resulted in the highest and lowest germination and emergence, respectively, were T5 (85%) and T4 (34%) for tall fescue, T8 (51%) and T4 (0.16%) for Kentucky bluegrass, T8 (86%) and T4 (0%) for bermudagrass, and T8 (20%) and T4 (0%) for zoysiagrass. For the papermill sludge compost, the treatments that resulted in the highest and lowest germination and emergence, respectively, were T5 (86%) and T7 (16%) for tall fescue, T1 (73%) and T4 (0.64%) for Kentucky bluegrass, T1 (89%) and T4 (2.8%) for bermudagrass, and T1 (28%) and T4 (0.37%) for zoysiagrass. The percent of germination and emergence of four turfgrass seeds decreased when depth of burial increased under the all compost sources, and the results of surface seeding on the compost or soil were significantly better than those of the other treatments.