Mobility of nitrogen and phosphorus solutes in fertilized and silicate-amended soil profiles
摘要
Enhanced rock weathering (ERW) using silicate minerals such as wollastonite is gaining attention for atmospheric CO2 removal, yet its effects on nutrient dynamics in agricultural soils remain underexplored. This study investigates how wollastonite skarn, when co-applied with nitrogen fertilizer as a low-dose blended formulation (wollastonite mixed with urea) or with phosphorus fertilizer as a high-rate amendment (large wollastonite addition with rock phosphate), influences nutrient mobility and availability in soil. Two soil column experiments were conducted using two distinct agricultural soils, one amended with urea and the other with rock phosphate, with and without wollastonite. Leachate and soil samples were analyzed over eight weeks (nitrogen) and 21 days (phosphorus) to assess pH, conductivity, and nutrient concentrations. In the nitrogen experiment, wollastonite co‑application with urea (+ MNF) delayed the nitrate peak by about one week compared to NF and showed slightly higher leachate conductivity and marginally higher pH than NF, indicating a modest buffering effect. In the phosphorus experiment, wollastonite co‑application (+ MPF) slightly increased soil pH, reduced dissolved reactive phosphorus leaching by 58%, and raised plant‑available phosphorus by ~ 58% (Olsen‑P) relative to PF, highlighting its role in moderating solution chemistry and enhancing phosphorus retention. These findings suggest that wollastonite may influence nutrient solubility and retention through pH modification and mineral interactions, potentially offering co-benefits for nutrient use efficiency. However, these effects might be soil-dependent and require further investigation. This study contributes to understanding the agronomic implications of ERW mineral applications and underscores the importance of evaluating nutrient cycling impacts when deploying silicate amendments for carbon sequestration in agricultural systems.