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• Silicate-containing amendments increased calcium and available silicate contents. • Silicate-containing amendments moderately increased soil fertility. • Silicate and lime co-application increased the relative change in soil fertility. • Long-term application of silicate and lime reduced C stratification. • Carbon stocks reduced in lime and silicate amended soils. Most agricultural soils are unproductive due to soil acidity which limits crop growth and yield. To ameliorate soil acidity constraints and enhance the ecosystem services the soil renders to achieve optimum crop yields, lime, and silicate are mostly used. However, there are few studies reporting the impacts of the combined application of silicate and lime on soil properties, soil fertility and carbon stocks and stratification in long-term experiments. This study evaluated the impacts of the combined application of silicate and lime on soil fertility indicators (pH, soil organic matter (SOM), available phosphorus, exchangeable potassium, magnesium, and calcium, and available SiO 2), carbon stratification and stocks in comparison to sole lime and sole silicate applied to a Fluvaquentic Eutrudepts over a 67-year period. Each treatment's rate of application was calculated to raise the soil pH to 6.5. Incorporation of the treatments increased the soil pH by 1.30, 1.22, and 1.35 folds in the sole silicate, sole lime, and combined silicate and lime-treated soils, respectively, relative to the baseline soil pH (5.5). The combined application of silicate and lime resulted in significant decreases in C stratification and C stocks. The significant reduction in the C stocks in the silicate and lime-treated soils implies that its long-term application could potentially reduce carbon sequestration and increase the carbon footprint of rice cultivation. This information is crucial to develop sustainable soil management interventions to curtail the environmental footprint in rice paddy ecosystems. Comparatively, the combined silicate and lime treatment caused an increase in the relative change of soil fertility by 65.7% and the average annual growth rate in the soil fertility improvement by 0.0115, as compared to the untreated soil. Among the soil variables, soil pH, exchangeable calcium, and available silicate contributed most to the variation the soil fertility. The obtained results could serve as a guide in revising the lime and silicate fertilization programs instituted by the Korean Government and reviewing national soil fertility management systems in temperate paddy ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: The stabilisation of soil organic matter (SOM) is the result of the simultaneous action of three mechanisms: chemical stabilisation, biochemical stabilisation and physical protection. The objectives of this study were (i) to evaluate carbon-protection mechanisms in different SOM pools in soil aggregates and (ii) to identify the association of Ca2+ with total organic carbon (TOC) under the influence of surface liming in a medium-textured Oxisol in a long-term experiment under no-till system (NTS) in southern Brazil (25° 10′ S, 50° 05′ W). The treatments consisted of application of zero or 6tons ha−1 of dolomitic lime on the soil surface in 1993 and a reapplication of zero or 3tons ha−1 of dolomitic lime in 2000 to plots with or without previous lime application. Soil samples collected at depths of 0–2.5, 2.5–5, 5–10 and 10–20cm were separated into seven aggregate classes. In each of these classes, TOC, particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) were analysed. The 8–19mm sized aggregates from the 0–2.5cm layer were assessed by energy-dispersive X-ray spectroscopy (EDS) for the elemental analysis of carbon (C) and calcium (Ca). The liming caused an accumulation of TOC in the aggregates, mainly at a depth of 0–2.5cm. The aggregates from soils treated with lime had a higher mean weight diameter (MWD) that resulted in the accumulation of TOC, especially in the 8–19mm aggregate class, that was linear and closely related with C input (R2 =0.99). The proportion of large aggregates in the treatments with lime was closely correlated with the TOC content of the whole sample. The largest dose of lime (9tons ha−1) resulted in higher TOC, POC and MAOC values, mainly in the 8–19mm aggregate class. The elemental analyses for C and Ca revealed similar spectra between them for the surface-liming treatments in the clay fraction found in the centres of the 8–19mm aggregates. The surface application of lime to NT fields provided greater stability and protection of the intra-aggregate C, presumably due to Ca2+ acting as a cationic bridge between OC and the kaolinite in the clay fraction. [Copyright &y& Elsevier]