Infrequent composted biosolids applications affect semi-arid grassland soils and vegetation

Area of Science:

• Environmental Science
• Soil Science
• Ecology

Background:

• Composted biosolids are increasingly reused in land applications.
• Monitoring repeated applications is crucial for sustainable management.
• Understanding long-term impacts on soil and plant communities is essential.

Purpose of the Study:

• To evaluate the short- and long-term effects of single and repeated composted biosolids applications.
• To assess impacts on soil chemistry and plant community composition in a semi-arid grassland.
• To determine the influence of varying application rates and timing on ecosystem health.

Main Methods:

• A split-plot field trial was conducted with six composted biosolids rates (0-30 Mg ha(-1)).
• Applications were surface-applied in 1991 (single) and 1991/2002 (repeated).
• Soil properties (pH, EC, N, P, metals) and plant community were analyzed 2-3 and 13-14 years post-application.

Main Results:

• Soil organic matter increased 13-14 years after application.
• Repeated applications boosted soil nitrogen (NO(3)-N, NH(4)-N) and reduced extractable barium (Ba).
• Increased native perennial grass cover and altered plant tissue nutrient concentrations (Cu, Mo, Zn, P, Ba) were observed.

Conclusions:

• Composted biosolids applications, even repeated ones, did not adversely affect the semi-arid grassland ecosystem at the studied rates.
• Long-term soil organic matter benefits and increased vegetation cover suggest positive outcomes for beneficial reuse.
• Further monitoring can refine management strategies for composted biosolids in similar ecosystems.