不同性质硅肥影响土壤生物有效态镉砷的主要因素

为研究硅肥影响土壤中生物有效态镉(Cd)和砷(As)的主要因素，选择不同性质的3种碱性硅肥Na₂SiO₃、 CaSiO₃与ASSF (pH 9～11)]和一种弱酸偏中性可溶硅肥(NSSF,pH 5～6)并通过添加不同用量硅肥(25～800 mg·kg^-1,以Si计)开展室内土盆试验，淹水共育21 d后对土壤基本理化性质进行检测，同时利用薄膜扩散梯度(DGT)提取土壤生物有效态Cd和As.结果表明，不同性质硅肥施用对土壤基本理化性质的影响差异显著，具体来说：3种碱性硅肥均显著提升土壤pH值(P<0.05),其中Na₂SiO₃提升土壤pH能力最强；而NSSF的施用则显著降低土壤pH值但提升了土壤Eh值(P<0.05),每单位质量(mg) Si添加量的NSSF可使土壤pH下降0.001 7个单位；在Si添加量达到400 mg·kg^-1后，3种碱性硅肥和NSSF土壤pH和Eh变化都趋于平缓. 4种不同性质硅肥提升土壤有效硅含量能...

Primary Factors Affecting Soil Bioavailable Cadmium and Asenic by Different Properties of Silicon Fertilizer

To clarify the primary factors affecting soil bioavailable cadmium (Cd) and arsenic (As) by silicon fertilizer, we chose different properties of silicon fertilizer, including three types of alkaline silicon fertilizerNa₂SiO₃, CaSiO₃, and ASSF (pH 9-11)] and one weak acid neutral soluble silicon fertilizer (NSSF, pH 5-6), to carry out a pot experiment by adding different amounts of Si fertilizer (25-800 mg·kg^-1, calculated as Si). After 21 days of flooding, soil basic physical and chemical properties, along with diffusive gradients in thin film Cd and As (DGT-Cd and DGT-As) were investigated. The results showed that the application of Si fertilizer with different properties had different significant effects on the basic physical and chemical properties of soil. Specifically, the three types of alkaline silicon fertilizer significantly increased the soil pH (P<0.05), among which Na₂SiO₃ exhibited the strongest ability; however, the application of NSSF remarkably reduced soil pH (P<0.05), and per unit (mg) Si application of NSSF could reduce soil pH by 0.0017 units. Furthermore, with each fertilizer application rate that reached 400 mg·kg^-1 (calculated as Si), the changes in soil pH and Eh tended to be gentle. The ability of the four types of silicon fertilizer to improve soil available silicon ranked as NSSF>Na₂SiO₃>ASSF>CaSiO₃. Additionally, the application of the three types of alkaline silicon fertilizer apparently decreased soil DGT-Cd while increasing soil DGT-As (P<0.05). When the addition rate of CaSiO₃ was up to 100 mg·kg^-1(calculated as Si), soil DGT-Cd concentration could be significantly decreased by approximately 50.89% without causing a significant increase in soil DGT-As concentration. Conversely, when the NSSF application rate was up to 400 mg·kg^-1 (calculated as Si), the soil DGT-As basically reached its steady-state, and the DGT-As reduction rate reached 85.87%. Strikingly, the correlation analysis of the influencing factors of soil DGT-Cd and DGT-As showed that soil pH was the main factor affecting soil bioavailable Cd and As (DGT-Cd and DGT-As), and the effect of soil available Si and P on soil Cd and As bioavailability was negligible. Consequently, soil DGT-Cd and soil DGT-As could reach a minimum when soil pH was adjusted to 6.5-7.0 or 5-5.5 by alkaline silicon fertilizer or NSSF, respectively. It is undoubtedly of great significance, to clarify the primary factors that influence soil bioavailable Cd and As to ensure food security production.