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Flue gas desulfurization gypsum (FGDG), the by-product of wet and semi-dry desulfu-rization processes, has been used us an alkali soil amendment in China. We evaluated the change in soil properties, agricultural production and the safety of FGDG as a soil amendment. Ax a result, soil pH and ESP (exchangeable sodium percentage) decreased and corn production increased in Kind-treated plots. The metal (B, Cr Mn. Ni, Cu, As. Cd. Pb) contents in soil. FGDG. and corn grains were quantified by ICP-MS. Consequently, the contents of almost all metals in FGDG were lower than in soil. Moreover, the contents of almost all of the metal in the corn grains in the FGDG-treated plots were almost the same or lower than those in the control plot. Statistical analysis indicated that there was no effect of gypsum application on the metal content in the com grains. Almost all of the metal contents were lower than the standard values set by FAO/WHO for human intake. The results showed that the FGDG from wet and semi-dry FGD processes is suitable as an alkali soil amendment. [ABSTRACT FROM AUTHOR]

Increasing soil carbon storage and biomass utilization is an effective process for mitigating global warming. Coal bio-briquettes (CBB) are made using two low-ranked coals with high sulfur content, corn stalks, and calcium hydroxide, and the combustion ash can ameliorate the physicochemical properties in salt-affected soil. CBB ash contains mainly calcium compounds, such as calcium sulfate, calcium hydroxide, and calcium carbonate, and coal fly ash and biomass ash. In this paper, changes in soil carbon and nitrogen content through salt-affected soil amelioration during 5 months using two CBB ashes and pig manure were examined in Northeast China. Application rates of CBB ash were 0 tha−1 (control), 11.6 tha−1, 23.2 tha−1, 46.4 tha−1, and 69.6 tha−1. Consequently, total carbon content in topsoil (0–0.15 m) after harvest of maize in all test fields indicated a range between 27.7 tCha−1 and 50.2 tCha−1, and showed increased levels compared to untreated salt-affected soil. In a 3.0% (69.6 tha−1) application plot of only CBB ash with higher carbon and higher exchangeable Ca2+, the carbon content increased by 51.5% compared to control plot, and changes in carbon sequestration compared to untreated soil was roughly twice that of the control plot. CBB ash contributed to carbon application and pig manure supply as a form of N fertilization in the case of all test plots. Changes in carbon content due to soil amelioration have a significant relationship with changes in corn production and soil chemical properties, such as pH, Na+, Cl−, sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP). Therefore, CBB production from low-ranked coal and waste biomass, and the use of CBB ash in agriculture is advocated as an effective means for sequestering carbon. [ABSTRACT FROM AUTHOR]

Soil degradation due to salinity and sodicity is one of the most important impediments to agricultural production. Coal bio-briquettes (CBB) made from coal, biomass, and desulfurizers have been proposed for use in desulfurization and usage of sustainable energy for coal and biomass in China. CBB ash contains calcium compounds such as calcium sulfate, calcium carbonate, and fly ash. The potential improvement of salt-affected soils using ashes from CBB made from two low-quality coals and/or organic manure (OM) was investigated in northeast China. The CBB ash application rates were 0 kg/m2 (control), 1.16 kg/m2, 2.32 kg/m2, 4.64 kg/m2, and 6.96 kg/m2. Following the application of CBB ash and/or co-application of OM, maize production increased significantly, compared to control plots. Moreover, co-application with OM resulted in higher maize production than application of CBB ash only. Soil pH, sodium adsorption ratio (SAR), exchangeable sodium percentage (ESP), and Na+, HCO3−, and CO32− concentrations decreased, and Ca2+, Mg2+, and SO42− concentrations increased from the start of the experiment to harvesting time. Maize production showed a tendency to increase with increasing CBB ash/OM application rates. The decrease in pH, ESP, and HCO3−, and increase in Ca2+ in the application plots over time was particularly remarkable. Moreover, saturated hydraulic conductivity (Ks) after CBB ash application in the slightly and moderately salt-affected soils increased with increasing application rates. In case of the highest application rate (6.96 kg/m2), using ash from CBB made from lower quality coal, pH and ESP decreased from 9.47 to 7.61, and from 7.0% to 0.98%, respectively, and Ks increased drastically by three orders of magnitude. Therefore, not only soil chemical properties, but also Ks, were improved in salt-affected soils using CBB ash. In addition, the heavy metal content in CBB ashes was below the standard values according to Chinese guidelines. Taken together, these results demonstrate the feasibility of sustainable methods for energy usage and environmental application in China. [ABSTRACT FROM AUTHOR]