Composted biosolids for golf course turfgrass management: Impacts on the soil microbiome and nutrient cycling

Abstract

Land application of biosolids is a primary means of recycling human waste products globally; however, because biosolids are also heavily enriched with nutrients and pollutants, it is necessary to consider the environmental impacts of land applications in various agro-ecosystems. To reduce costs and divert waste, biosolids from Joint Base Lewis-McChord, a military installation south of Tacoma, WA, USA, are composted with organic materials derived from the base itself. The potential for turfgrass management using the composted biosolids was tested in a field study at the military recreation facility, Eagles Pride golf course. The composted biosolids were surface-amended to golf course fairways (n = 3) at a rate of 46 Mg ha−1, in split applications, fall and spring, over two years, 2015 and 2016. Soil bacterial and fungal community responses were evaluated in amended and unamended soils from each fairway, along with soil chemical properties, including soil pH, total carbon (C), total nitrogen (N), and the C:N ratio. Soil microbial community analysis on soils sampled pre- and post-amendment did not demonstrate changes in community structure as a result of the composted biosolids application. Differences observed in soil microbial community structure appears to reflect edaphic and vegetative differences between fairways. Generally, correlations between soil properties and bacterial community OTUs were stronger than those with fungal OTUs, and predicted bacterial community functional analysis revealed several KO term groups were significantly correlated with soil TC and TN. Turfgrass biomass was unaffected, while leaf tissue N was increased by 4.5 and 10.6% in 2015 and 2016, respectively. These results suggest that amendment with composted biosolids does not strongly impact microbial communities across two years; however, long-term amendment could have affects that are not detected during this short-term study.