Surface-Applied Biosolids Enhance Soil Organic Carbon and Nitrogen Stocks but Have Contrasting Effects on Soil Physical Quality

Abstract

Mid-to long-term impacts of land applying biosolids will depend on application rate, duration, and method; biosolids composition; and site-specific characteristics (e.g., climate, soils). This study evaluates the effects of surface-broadcast biosolids application rate and duration on soil organic carbon (SOC) stocks, soil aggregate stability, and selected soil hydraulic properties in a municipally operated, no-till forage production system. Total SOC stocks (0-45 cm soil) increased nonlinearly with application rate in perennial grass fields treated for 8 years with 0, 20, 40, or 60 Mg of Class B biosolids (DM) ha −1 yr −1 (midterm treatments). Soil organic C stocks in long-term treatment fields receiving 20 years of 20 Mg ha −1 yr −1 were 36% higher than those in midterm fields treated at the same rate. Surface-applying biosolids had contrasting effects on soil physical properties. Soil bulk density was little affected by biosolids applications, but applications were associated with decreased water-stable soil aggregates, increased soil water retention, and increased available water-holding capacity. This study contrasts the potential for C storage in soils treated with surface-applied biosolids with application effects on soil physical properties, underscoring the importance of site-specific management decisions for the beneficial reuse of biosolids in agricultural settings.

Measuring Rotation and Manure Effects in an Iowa Farm Soil Health Assessment

“…In another study, Jin et al (2015) found that the fraction of water stable aggregates did not increase in plots receiving biosolids for 20 yr, but changes were noted at another site after receiving biosolids for only 8 yr. Both sites showed a nonlinear increase in total C stocks as manure application rates increased (Jin et al, 2015). One possible reason for this apparent discrepancy is that development of stable soil aggregates is influenced not only by total carbon content, but also by root derived C and decomposition .…”

“…For example, 9 yr of continuous animal manure application increased SOC, POM-C, MBC, and soil P, but had no effect on aggregate stability (Delate et al, 2013). In another study, Jin et al (2015) found that the fraction of water stable aggregates did not increase in plots receiving biosolids for 20 yr, but changes were noted at another site after receiving biosolids for only 8 yr. Both sites showed a nonlinear increase in total C stocks as manure application rates increased (Jin et al, 2015).…”

“…The routine, but not annual, application of the manure/biosolids mixture was not sufficient to increase soil organic carbon over time. In studies where manure application occurs annually, soil organic carbon stocks may increase (Delate et al, 2013;Jin et al, 2015).…”

Fate of Antibiotics and Antibiotic Resistance during Digestion and Composting: A Review

“…Waste-derived soil amendments such as manure and biosolids contain all nutrients essential for plant growth and can replace or complement inorganic fertilizers in many types of agricultural production systems (Brown et al, 2011;Gale et al, 2006). Beyond being a source of nutrients, organic soil amendments are valuable sources of stable organic carbon (Wuest and Gollany, 2013;Jin et al, 2015). Soil organic carbon is an indicator of soil quality.…”

Soil health assessments: how and why?

“…The soil health assessment data were also used to estimate the potential impact of the animal manure/municipal biosolid application on the SOC pool. Starting with the maximum application rate (16 tons/ac) and assuming (1) a carbon content of 58% and (2) that 80% of the material decomposed within one year of application (Magdoff and van Es, 2010), Table 2 shows that the five‐year rotation effect (with two applications of animal manure/municipal biosolids) on SOC stocks would probably be non‐detectable through routine soil testing. Our reason for this conclusion is that when averaged across all four treatments, the surface (0 to 6 inch) soil bulk density was approximately 1.53 g/cm 3 .…”