How Biosolids Can Benefit Wildlife and Ecosystem Health
Biosolids are widely recognized for their benefits to soil health, vegetation growth, and land restoration. When added to soil, they provide organic matter and slowly release nutrients, supporting healthy soils and plant productivity. Healthy plant communities, in turn, form the foundation of resilient ecosystems by providing habitat and food sources for birds, mammals, and other wildlife.
This post summarizes a research case study that examined wildlife responses to biosolids-amended grasslands in North Carolina.
Case Study: Effects of Biosolids on Grassland Habitat and Wildlife
Researchers from the United States Department of Agriculture’s Wildlife Service program conducted a two-year study at Marine Corps Air Station Cherry Point to evaluate whether long-term application of biosolids to grasslands altered plant and animal communities (1).
Lime-stabilized biosolids were applied for 17 years from 1989 to 2005 at approximately 7.6 megagrams per hectare on a dry weight basis to grassland areas near marine airfield runways. Researchers assessed whether these applications changed habitat conditions and influenced wildlife presence by comparing areas with and without biosolids application. Specifically, the study assessed:
Plant height, composition, and overall cover,
Bird abundance and species diversity, and
White-tailed deer abundance.
From 2003 to 2005, researchers monitored ten grassland plots: five treated with biosolids and five untreated controls. Each plot was approximately 1.7 hectares in size. Researchers measured vegetation height and composition and conducted standardized wildlife surveys across morning, mid-day, and evening periods each month. Bird use was assessed through point counts, while white-tailed deer activity was evaluated using spotlight surveys.
The results showed that long-term biosolids application significantly improved grassland vegetation structure and bird communities. Biosolids-treated plots developed taller, denser plant growth and greater overall vegetation cover compared to untreated plots.
These improvements in vegetation were associated with increased use by several grassland bird species. Researchers observed more than twice as many birds in biosolids-treated plots compared to control plots. As seen in Figure 1 below, species such as eastern meadowlarks, European starlings, and American robins were especially common in biosolids-amended plots. The greater use of these plots suggests that these more densely-vegetated habitats provided favorable conditions for foraging, shelter, or seasonal use.
The study did not find a significant difference in white-tailed deer use between treated and untreated grassland plots.
Figure 1 - Bird Observations in Biosolids Treated and Untreated Plots
Overall, this study illustrates how biosolids can provide ecosystem benefits beyond soil fertility and plant growth. By increasing plant biomass and altering vegetation structure, biosolids can enhance habitat conditions that support increased use by certain wildlife species, such as grassland birds. When thoughtfully managed, biosolids can be a valuable tool for improving ecosystem function while contributing to sustainable resource recovery and responsible land stewardship practices.
References
(1) Wildlife responses to long-term application of biosolids to grasslands in North Carolina. Research paper link.
Additional Research on Wildlife Benefits of Biosolids Land Application
Biosolids application increases grasshopper abundance in the short term in a northern Canadian grassland. Research paper link.
Effects of biosolids amendments on American Kestrel nest site selection and diet. Research paper link.
Effect of habitat area and isolation on fragmented animal populations. Research paper link.
Grassland compost amendments increase plant production without changing plant communities. Research paper link.