Evaluation of Compost Topdressing and Compost Tea Applications on Sports Field Turfgrass Swards.

Athletic fields are becoming target sites for compost topdressing, as the trend for municipalities to divert organic materials from landfills increases and regional composting facilities are employed. While many provincial and state extension websites recommend topdressing home lawns with compost and/or vermicompost, there is limited scientific evaluation of these products and their teas that quantify the ecological response of turfgrass and the surrounding rhizosphere to compost, vermicompost, aerated vermicompost tea, and thermophilic compost tea applications. The overall objective of the study was to determine the effect of compost topdressing and compost tea applications on actively worn Kentucky bluegrass (KB), and consisted of three separate experiments. Experiment 1 evaluated rates and timing of municipal compost and vermicompost on worn KB and their effects on wear tolerance. Experiment 2 evaluated the effects of compost tea made from either municipal or vermicompost on preventing wear damage on KB turf. Experiment 3 evaluated the effects of both compost topdressing and compost teas on in-use play fields. Experiments 1&2 were performed on KB that was worn with a Brinkman wear simulator for the duration of the growing season (May-Sept.). Plots were treated with either thermophilic compost or vermicompost topdressing at depths of: 0.25 cm, 0.5 cm, or 1.0 cm, and were topdressed either once or 3 times throughout the growing season in experiment 1. Compost tea applications were applied at a rate of 750 ml m^-2, and either biannually (spring and fall) or monthly during the growing season in experiment 2. Compost topdressing improved the performance of all plots, and those that were topdressed 3 times per season with 0.25 or 0.5 cm had softer surface hardness ratings and the highest quality ratings. The compost tea applications alone did not improve wear tolerance. The use of compost topdressing (0.5 cm depth) combined with compost teas improved the overall turfgrass quality of the in-use fields evaluated regardless of the type of compost used.