Suitable Chemical Properties of Animal Manure Compost to Facilitate Pb Immobilization in Soil

Role of Inorganic and Organic Fractions in Animal Manure Compost in Lead Immobilization and Microbial Activity in Soil

“…In contrast, 25% inorganic AMC can alter lead phases to be more insoluble and simultaneously enhance microbial activities, whereas the water-soluble lead level is higher than that in the soil without compost during the first 30 days after the application. This is consistent with the result of Katoh et al [17], who indicated that the application of 25% inorganic swine manure compost could alter lead phases to be more insoluble and improve plant growth and microbial enzyme activities; however, the level of water-soluble lead was higher than that in the cattle manure compost during the early stage of incubation (90 days after application). These findings suggest that AMCs cannot immobilize both lead and restore microbial activity.…”

“…These observations would be explained by the higher level of water-soluble organic matter and its sorption and decomposition in the soil thereby increasing the incubation time. The water-soluble organic matter can easily form complexes with lead ions, and its complexes could enhance the lead mobility in the soil [17,32,33]. Therefore, at the early stage of incubation, the high level of water-soluble organic carbon would result in an enhancement of the lead mobility in the soil treated by AMC with inorganic-to-organic ratios of 0/100 and 25/75.…”

“…Animal manure compost (AMC), which is the most abundantly found organic waste material in Japan, can immobilize heavy metals and improve plant growth and microbial activity [8][9][10][11][12][13][14][15][16] by supplying nutrients to plant and soil biota. Therefore, in addition to lead immobilization, the application of AMC to lead-contaminated soil can help rehabilitate soil ecosystems, which inorganic immobilization materials cannot [17]. Numerous studies have investigated the effectiveness of AMC for lead immobilization [18,19]; however, consistent conclusions on the mechanisms behind this process have not been obtained as such immobilization that greatly depends upon the AMC type, that is, AMC's physicochemical properties.…”

“…These results imply that the inorganic component in AMC has a crucial role in lead immobilization, and AMC with a higher inorganic content is more suitable. However, to rehabilitate microbial activity, the organic component in AMC is also required since it supplies sufficient nutrients to soil microorganisms [17]. This component, however, may negatively affect lead mobility; water-soluble organic matter in AMC reacts and forms complexes with lead ions, resulting in enhancements in lead mobility.…”

Potential for Lead Release from Lead-Immobilized Animal Manure Compost in Rhizosphere Soil of Shooting Range

“…Although these advantages may encourage the application of AMC onto contaminated soils, less is known about the mechanisms of immobilization by AMC [12,13] compared with other inorganic and organic waste materials [14], particularly the applicability of AMC to the shooting range soil and the remobilization of lead that was once immobilized by AMC. Katoh et al [13,15,16] conducted several studies to elucidate the mechanisms of lead immobilization by AMC using the inorganic and organic components of specifically fractionated AMC to understand the suitable chemical properties of AMC to immobilize lead present in the shooting range soil. The studies revealed that the inorganic components in AMC can immobilize lead more effectively than the organic components [13].…”