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With the increase in iron/steel production, the higher volume of by-products (slag) generated necessitates its efficient recycling. Because the Linz-Donawitz (LD) slag is rich in silicon (Si) and other fertilizer components, we aim to evaluate the impact of the LD slag amendment on soil quality (by measuring soil physicochemical and biological properties), plant nutrient uptake, and strengthens correlations between nutrient uptake and soil bacterial communities. We used 16 S rRNA illumine sequencing to study soil bacterial community and APIZYM assay to study soil enzymes involved in C, N, and P cycling. The LD slag was applied at 2 Mg ha −1 to Japonica and indica rice cultivated under flooded conditions. The LD slag amendment significantly improved soil pH, plant photosynthesis, soil nutrient availability, and the crop yield, irrespective of cultivars. It significantly increased N, P, and Si uptake of rice straw. The slag amendment enhanced soil microbial biomass, soil enzyme activities and enriched certain bacterial taxa featuring copiotrophic lifestyles and having the potential role for ecosystem services provided to the benefit of the plant. The study evidenced that the short-term LD slag amendment in rice cropping systems is useful to improve soil physicochemical and biological status, and the crop yield. Soil enzyme activities.Labile carbon degrading enzymes such as α-glucosidase, β-glucosidase, α-galactosidase, β-galactosidase, α-mannosidase, and α-fucosidase which can degrade maltose, cellobiose, melibiose, lactose, mannose, and fructose, respectively, markedly increased in the slag amendment treatments in comparison to the unamended treatments, irrespective of rice cultivars (Fig. 1). Likewise, recalcitrant carbon degrading enzymes such as esterase, lipase, and N-acetyl-β-glucosaminidase which can degrade hemicelluloses and polysaccharide respectively, increased by the slag amendment. Notably, the increase was more in labile carbon degrading enzymes (mostly β-glucosidase, and β-galactosidase) compared to the recalcitrant carbon degrading enzymes. The LD slag amendment also noticeably increased soil enzyme activities involved in nitrogen cycling (i.e., leucine-aminopeptidase and trypsin) and phosphorus cycling (i.e., alkaline phosphomonoesterase and phosphohydrolase). Notably, the increase in soil enzyme activities was more prominent in Indica in comparison to Japonica rice variety. Among the C cycling enzyme, β-glucosidase, and β-galactosidase were dominant, whereas among the N cycling enzyme, aminopeptidase and among the P cycling enzyme, alkaline phosphomonoesterase were dominant in the paddy soil (Fig. 1).Relative abundance and diversity of rhizosphere bacterial community. The most abundant (≥ 1.0%) bacterial phyla across treatments were Proteobacteria (34-48%), Fermicutes (15-17%), Actinobacteria (7-18%), Acidobacteria (3-7%), Bacteroidetes (2-6%), Nitrospirae (2-3%), and Chloroflexi (1-4%). The LD slag amendment significantly (P < 0.05) increased the relative abundance of Proteobacteria by 28.9 and 2...

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18Rye (Secale cerealis) has been widely cultivated to improve soil quality in temperate paddies. However, 19its biomass incorporation can significantly increase greenhouse gas emissions, particularly the emission

The aerenchymal transport of oxygen to rice roots has significantly influenced the anaerobic root zone of flooded paddy soils. Therefore, the visualization of redox dynamics may be useful to characterize rice root oxidation potentials and the dynamics of redox-influenced ions in the root zone of paddy soils. In order to investigate the interaction between root oxidation potential and Fe uptake of (a) six different rice cultivars (Oryza sativa L.; Chuchung, Dongjin, Ilmi, Junam, Nampyeong, and Samkwang) were monitored in a flooded paddy soil with the aid of rhizotron experiment throughout the vegetation period, (b) digital images of the root zone were taken at the important growing stages, and (c) rice Fe uptake was characterized simultaneously. The images were processed by image analysis to display the reduction and oxidation areas in the root zones, and the distinct areas which were colorized due to varying soil redox changes were localized and quantified. Oxidized areas were mainly observed in the surrounding active roots and in a distinct layer on the soil surface. The selected rice cultivars have shown significantly different root-oxidized areas at the same rice growing stage. Root-oxidized area was significantly and positively correlated with total Fe content of rice root, but negatively correlated with the inner root Fe content. Rice cultivars having higher root oxidation potential precipitated more Fe on the outer root surface in the form of Fe plaques. In conclusion, digital image analysis is an effective tool for evaluating the oxidizing potential of rice root under anaerobic soil condition.