Characterization of Physically Fractionated Wollastonite-Amended Agricultural Soils

Abstract

Wollastonite is a natural silicate mineral that can be used as an agricultural soil amendment. Once in the soil, this mineral undergoes weathering and carbonation reactions, and, under certain soil and field crop conditions, our previous work has shown that this practice leads to accumulation of inorganic carbon (calcium carbonate). Mineral carbonation is the carbon sequestration approach with the greatest potential for sequestration capacity and permanency. Agricultural lands offer vast areas onto which such minerals can be applied, while benefiting crops. This work illustrates a technique to separate wollastonite-containing soils into different fractions. These fractions are characterized separately to determine organic and inorganic content, as well as to determine the chemical and mineral composition. The aim is to detect the fate of wollastonite in agricultural soils, and the fate of weathering/carbonation products in the soil. The soils used in the study were collected from soybean and potato farmlands in Southern Ontario, and from an experimental pilot plot. Soil fractionation was done using sieving, and soil fractions were analyzed by a calcimeter, X-ray diffraction, and loss-on-ignition. Acid digested samples were measured by Inductively Coupled Plasma Mass Spectrometry. Carbonates and wollastonite were enriched by fractionation.

Mineral–Soil–Plant–Nutrient Synergisms of Enhanced Weathering for Agriculture: Short-Term Investigations Using Fast-Weathering Wollastonite Skarn

“…Each gram of coated fertilizer contains 18.85% of milled wollastonite skarn, which equals 0.60 g of wollastonite skarn in coated treatment. By considering the mineral composition in wollastonite skarn, and assuming that calcium released by the weathering of wollastonite and diopside can result in pedogenic carbonate formation (as observed by Dudhaiya et al, 2019), each gram of wollastonite skarn can potentially sequester 0.206 g of CO 2 as pedogenic CaCO 3 . In the present study, the SIC level in spring rye soil for three treatments showed a positive correlation between the SIC level and the application of wollastonite skarn.…”

Multiscale Process Intensification of Waste Valorization Reactions

“…In Dudhaiya and Santos, 33 several examples of our prior research employing LDA were exemplified (Figure 5), such as the growth of particles due to the deposition of a carbonate layer, the shrinkage of particles due to attrition that even more extensively reduces particle size when the mineral is weakened by the formation of carbonate-and silica-rich layers, 7 and even how the polymorphism of carbonates affects particle size and distribution. 26 Inspired by these observations, the work of Dudhaiya et al 14 translated this strategy of thinking about particle size distribution to the field of ERW, whereby soils were physically fractionated as a means to concentrate pedogenic carbonates and improve their detection and quantification accuracy via XRD and calcimetry, respectively. Notably, one of the goals of this research was to ascertain that the detection of pedogenic carbonates in short-term experiments using wollastonite was not an artifact of the technique and the hypothesis tested was that artifacts are not concentrated by fractionation.…”

Natural and Human-Induced Factors on the Accumulation and Migration of Pedogenic Carbonate in Soil: A Review

“…As is the case with natural PC formation, various climatic and environmental factors affect SIC formation in engineered soils [60,72]. This includes pH [64,67,72], fineness of particles [72,74], hydrological parameters (redistributing SIC content over the soil profile) [60,72], and additive mineral characteristics [62].…”