Impacts of Steel-Slag-Based Silicate Fertilizer on Soil Acidity and Silicon Availability and Metals-Immobilization in a Paddy Soil

Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. A consecutive early rice-late rice rotation experiment was conducted to test the impacts of steel slag on soil pH, silicon availability, rice growth and metals-immobilization in paddy soil. Our results show that application of slag at a rate above higher or equal to 1 600 mg plant-available SiO2 per kg soil increased soil pH, dry weight of rice straw and grain, plant-available Si concentration and Si concentration in rice shoots compared with the control treatment. No significant accumulation of total cadmium (Cd) and lead (Pb) was noted in soil; rather, the exchangeable fraction of Cd significantly decreased. The cadmium concentrations in rice grains decreased significantly compared with the control treatment. In conclusion, application of steel slag reduced soil acidity, increased plant–availability of silicon, promoted rice growth and inhibited Cd transport to rice grain in the soil-plant system.

渣基硅酸盐肥料（slag-based silicate fertilizer）已被广泛用于提升土壤有效硅含量与作物生产能力。本研究开展了连作早稻-晚稻轮作试验，以探究钢渣（steel slag）对稻田土壤pH值、有效硅含量、水稻生长及重金属固定效果的影响。研究结果表明，与对照组相比，当施用量达到每千克土壤含1600毫克植物有效二氧化硅（SiO₂）及以上时，可提升土壤pH值、水稻秸秆及籽粒干重、植株有效硅浓度以及稻株地上部硅含量。土壤中总镉（Cd）与总铅（Pb）未出现显著累积，反而镉的可交换态占比显著降低。水稻籽粒中的镉浓度较对照组显著下降。综上，施加钢渣可降低土壤酸度，提升硅的植物有效性，促进水稻生长，并抑制土壤-植物系统中镉向水稻籽粒的转运。