Chemically Precipitated Struvite Dissolution Dynamics over Time in Various Soil Textures

Wastewater‐recovered struvite effects on total extractable phosphorus compared with other phosphorus sources

“…The major cause of the variation in soil pH among fertilizers likely occurred due to the different levels of affinity of the cations (i.e., Ca 2+ , Mg 2+ , and NH 4 + ) present in the fertilizers used in the incubation (Table 1). The various cations (i.e., Ca 2+ , Mg 2+ , and NH 4 + ), which have a greater affinity for cation exchange sites than H + , likely displaced H + into the soil at different concentrations (Anderson et al., 2020; Montalvo et al., 2014; Nascimento et al., 2018). Soil pH was also affected by the different compositions of the fertilizers themselves, which included different forms of P ions (H 2 PO 4 – and HPO 4 2– ; FTRC, 2015) and various cations including Ca 2+ , Mg 2+ , and NH 4 + .…”

“…Additionally, due to its chemical composition, struvite is also considered to be a potential fertilizer P source for row-crop agricultural use in the United States (Anderson et al, 2020) and in Europe (Huygens & Saveyn, 2018), which could help decrease the global dependence on traditional fertilizer P sources that are derived from the finite supply of mined RP. Once land-applied, P availability and mobility in a moistsoil environment is affected by several fertilizer and soil properties, such as granule size and P-species composition of fertilizer P materials (i.e., ammonium-based vs. calcium-based phosphates), soil pH, clay and soil organic matter (SOM) concentrations, cation exchange capacity (CEC), exchangeable soil aluminum (Al), calcium (Ca), and iron (Fe) concentrations, and ambient P concentrations (Nascimento et al, 2018).…”

“…Two watering schemes were used in the soil incubation to mimic common field practices for rice production. For the first month of the incubation, soil cups were watered in a similar procedure as described in Anderson et al (2020), in which soil cups were gravimetrically watered to a predetermined target mass for each soil. The target watering mass was derived from the measured gravimetric water content of the air-dried soils and the estimated bulk densities from Soil Water Characteristics sub-routine of the Soil Plant Atmosphere Water (SPAW) model (version 6.02.75, USDA, 2017; Saxton et al, 1986).…”

“…to evaluate initial soil property differences among the three soils. Based on a similar split-split-plot, randomized experimental design as described by Anderson et al (2020), a three-factor ANOVA was conducted in SAS using the PROC GLIMMIX procedure to evaluate the effects soil (SiCL, SiL 1, and SiL 2), fertilizer amendment (ST, TSP, MAP, and UC), sample time (0.5, 1, 2, 3, and 4 mo), and their interactions on the net change in soil pH and total WS and M3 P, K, Mg, Ca, and Fe concentrations from their initial magnitudes. The whole-plot factor was soil, the split-plot factor was fertilizer amendment, and the split-split-plot factor was time, all of which were fixed effects and only replication was a random effect.…”

“…Summary of initial soil properties (n = 3) among soils used in the soil incubation (adapted fromAnderson et al, 2020) Means in a row with different letters are different at p < .05. NOTE.…”