Submitted to: Applied and Environmental Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2014
Publication Date: 5/6/2015
Citation: Jin, V.L., Potter, K.N., Johnson, M., Harmel, R.D., Arnold, J.G. 2015. Surface-applied biosolids enhance soil organic carbon and nitrogen stocks but have contrasting effects on soil physical quality. Applied and Environmental Soil Science. DOI: 10.1155/2015/715916.
Interpretive Summary: Land application of municipal wastes can be a cost-efficient disposal tool when applied appropriately. Surface applying biosolids may have different impacts on soils compared tilling biosolids into soils. The goal of this study was to examine the effects of biosolids application rate and application history for a forage production system at a municipal recycling facility that uses surface-applied biosolids. We found that adding biosolids increased soil organic carbon storage compared to control fields with no biosolids application. Biosolids additions had different impacts on soil physical characteristics affecting soil water erosion potential and soil water availability. Biosolids did not improve soil physical characteristics related to soil aggregate stability, which affects the potential for sediment losses in surface run-off. Biosolids additions did improve soil water holding characteristics, suggesting possible reduction in run-off because soils can hold more water before becoming saturated. These results differ from other field studies and show that site-specific characteristics are important for long-term management decisions in biosolids recycling systems.
Technical Abstract: Beneficial reuse of biosolids through land application can increase soil organic carbon (SOC) storage while also improving soil physical properties that affect fertility. The effects of continuous biosolids applications in the mid- to long-term, however, are likely to depend on application rate, method, biosolids composition, and site-specific characteristics (e.g. climate, soils). The objectives of this study were to evaluate the effect of application rate and duration on SOC stocks, soil aggregate stability, and selected soil hydraulic properties at a municipal biosolids recycling facility that surface-applies Class B biosolids on large-scale perennial forage production fields. Relative to unamended controls, SOC stocks (0-45 cm soil) were 9% lower in fields treated with 20 Mg DM ha-1 yr-1 but were 26% and 90% greater under 40 and 60 Mg ha-1 yr-1, respectively, after 8 years of continuous annual applications. Increases in SOC after 20 years of application at the lowest rate were 23% greater than controls. Surface-applying biosolids had contrasting effects on soil physical properties. Biosolids applications generally did not affect soil bulk densities, but applications decreased water-stable soil aggregates while also increasing soil water retention and available water-holding capacity. Although this study demonstrated the potential for carbon storage in soils treated with surface-applied biosolids, the contrasting effects on soil physical properties underscore the importance of site-specific management decisions for the beneficial reuse of biosolids in agricultural settings.