The long-term effect of sludge application on Cu, Zn, and Mo behavior in soils and accumulation in soybean seeds

Abstract

A long-term greenhouse column experiment using two soils of different textures amended with dewatered, composted and alkaline-stabilized sludges (biosolids) tested the effect of aging on trace metal solubility, mobility and crop uptake over 15 cropping cycles. Specifically, soil chemical properties and extractability of Cu, Zn and Mo were measured after each cropping cycle, and soybeans (Glycine max (L.) Merr.) grown as the final crop were analyzed for those metal concentrations in the seeds. Significant Cu loss from the surface soil through leaching, and increased Zn extractability resulting from soil acidification were evident in the early cropping cycles shortly after sludge application, with the degree of Cu mobilization and soil acidification strongly dependent on the type of soil and sludge. Liming to counter acidification in later cycles enhanced Mo extractability and bioavailability substantially, with some sludge treatments producing soybean seeds with Mo concentrations up to 5 times greater than the control. Aging effects were difficult to discern for trace metals in this long-term study, since soil pH changes caused by sludge and liming amendments dominated metal solubility and crop uptake.

Relationship between photosynthetic capacity, nitrogen assimilation and nodule metabolism in alfalfa (Medicago sativa) grown with sewage sludge

“…Sewage sludge addition also improves soil fertility due to increased availability of some nutrients (N and P), and addition of mineral fertilizer (N) produced the same fertilizer effect as the sludge because our experimental design was performed by equalizing the amounts of main nutrients added (Table 1). Sewage sludge application also led to increases in soil DTPA-extractable heavy metals (Cd, Cu, Fe, Mn, Mo, Pb and Zn) as it has been observed previously [20,21,[50][51][52]. Besides, the addition of organic (RS) or inorganic (N) amendments to substrate produced similar amount of heavy metals in plant tissues being significant from some elements (Cr, Cu, Fe, Ni and Zn) with respect to untreated (R) alfalfa (Table 2).…”

Effect of soil metal contamination on glyphosate mineralization: Role of zinc in the mineralization rates of two copper‐spiked mineral soils

“…Because of repeated applications or coapplications of fungicides, waste materials, animal manure, and herbicides on agricultural lands, contamination by more than one metal may impact the soil ecosystem. Previous studies in our laboratory with metal-spiked and sludge-amended soils illustrated the complicated nature of the combined toxic effects of Cu, Zn, and Mo at various loading rates on different biological endpoints [20][21][22]. To understand better the complexity of agricultural soils when both herbicides and metals are present, there is a need for a systematic investigation into herbicide degradation rates affected by the type of the soil, the nature of the metal, the level of metal loading, and the particular combinations of metals.…”

Surface chemistry variations among a series of laboratory-produced biochars

“…Zeta potential (ZP), which is related to a particle's surface charge, can be measured by tracking suspended particle movement in a voltage field, but is also dependent upon the concentration and speciation of electrolytes, dielectric constant of the medium. But solution pH usually has the strongest influence on the sign and magnitude of ZP (Asadi et al, 2009;Han et al, 2004;Kim et al, 2007). The pH at which the ZP becomes zero is the isoelectric point (IEP).…”