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The deficiency of available silicon (Si) incurred by year-round agricultural and horticultural practices highlights the significance of Si fertilization for soil replenishment. This study focuses on a novel and economical route for the synthesis of Si fertilizer via the calcination method using talc and calcium carbonate (CaCO3) as starting materials. The molar ratio of talc to CaCO3 of 1:2.0, calcination temperature of 1150 °C and calcination time of 120 min were identified as the optimal conditions to maximize the available Si content of the prepared Si fertilizer. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) characterizations elucidate the principles of the calcination temperature-dependent microstructure evolution of Si fertilizers, and the akermanite Ca2Mg(Si2O7) and merwinite Ca3Mg(SiO4)2 were identified as the primary silicates products. The results of release and solubility experiments suggest the content of available metallic element and slow-release property of the Si fertilizer obtained at the optimum preparation condition (Si-OPC). The surface morphology and properties of Si-OPC were illuminated by the results of scanning electron microscope (SEM), surface area and nitrogen adsorption analysis. The acceleration action of CaCO3 in the decomposition process of talc was demonstrated by the thermogravimetry-differential scanning calorimetry (TG-DSC) test. The pot experiment corroborates that 5 g kg−1 soil Si-OPC application sufficed to facilitate the pakchoi growth by providing nutrient elements. This evidence indicates the prepared Si fertilizer as a promising candidate for Si-deficient soil replenishment.

Silicon (Si) plays an essential role in the mineral nutrition of plants. This creates a need to improve tools can provide plant-available Si (PAS) and increase its use efficiency (UE), especially under sandy soil conditions. This study was conducted to estimate Si use efficiency (Si-UE) in sandy soil treated by a hydrogel (water-absorbing polymer) loaded by Si. A field experiment was carried out using a hydrogel (H, 0.7 g kg−1 soil) that was mixed with quartz silica (S, 98.4% SiO2) to give HS homogenous mixtures with three mixing ratios 1:0.5 (HS1), 1:1 (HS2) and 1:1.5 (HS3). The HS mixture was sprayed by potassium humate solution (K-humate, 0.5 mL g−1 hydrogel) to obtain HS1K, HS2K, and HS3K treatments. All treatments were mixed with soil subsurface before wheat (Triticum aestivumL.) cultivation. Results showed that wheat yield and seed yield (t ha−1) increased significantly by applied treatments compared to the control C in the range 9.52–23.80% and 2.59–30.60%, respectively. The HS3 treatment significantly increased the total nitrogen N (mg kg−1) in seeds by 34.99%, phosphorus P by 17.46%, and potassium K by 4.84%. Available Si in soil (mg kg−1) increased in the order HS1 < HS2 < HS3, and with K-humate in the order HS1K < HS2K < HS3K. Total Si (g kg−1) in wheat seeds increased significantly in the order HS1 < HS2 < HS3, and HS1K < HS2K < HS3K with K-humate. Silicon use efficiency may decrease as the rate of applied Si increases. [ABSTRACT FROM AUTHOR]

A silicon–potash (Si–K) fertilizer was synthesized from magnesium slag (Ms), which is an industrial residue generated from the refining process of magnesium and magnesium alloy. Nutrient release characteristic and the effect of Si–K fertilizer on soil fertility and agronomic performance were evaluated so that an alternative, effective, and sustainable method of utilizing Ms in Chinese agriculture could be developed. The results showed that unevenly shaped aggregates were formed, and Ca, K, Si, and Mg coexisted in a mixed heterogeneous mass of amorphous and crystalline materials when Ms reacted with K2CO3 at high temperature. The solubility of K+ in synthetic Si–K fertilizer was decreased, and that of Si was improved due to K+ entering in the Si–O network resulting in the depolymerization of Si–O tetrahedrons. Application of Si–K fertilizer improved the accumulation of K and Si in soil and two plant tissues. Maize plants exhibited larger K demand to maintain growth compared to pakchoi plants. And as a monocotyledon of gramineae, maize could accumulate more Si concentration than pakchoi, which is a dicotyledon of non-gramineae. Compared to K2SO4, Si–K fertilizer prepared from Ms had an equivalent and superior impact on the growth of pakchoi and maize plants, respectively. In conclusion, Si–K fertilizer synthesized from Ms has a potentially beneficial application in the calcareous cinnamon soil of Northern China. Abbreviation: Ms: Magnesium slag; Si–K fertilizer: silicon–potash fertilizer; NUE: nutrient use efficiency; K: potassium; Si: silicon; NER: nutrient efficiency ratio; PE: physiological efficiency; AE: agronomic efficiency; APE: agrophysiological efficiency; ANR: apparent nutrient recovery efficiency [ABSTRACT FROM AUTHOR]

The deficiency of available silicon (Si) incurred by year-round agricultural and horticultural practices highlights the significance of Si fertilization for soil replenishment. This study focuses on a novel and economical route for the synthesis of Si fertilizer via the calcination method using talc and calcium carbonate (CaCO3) as starting materials. The molar ratio of talc to CaCO3 of 1:2.0, calcination temperature of 1150 °C and calcination time of 120 min were identified as the optimal conditions to maximize the available Si content of the prepared Si fertilizer. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) characterizations elucidate the principles of the calcination temperature-dependent microstructure evolution of Si fertilizers, and the akermanite Ca2Mg(Si2O7) and merwinite Ca3Mg(SiO4)2 were identified as the primary silicates products. The results of release and solubility experiments suggest the content of available metallic element and slow-release property of the Si fertilizer obtained at the optimum preparation condition (Si-OPC). The surface morphology and properties of Si-OPC were illuminated by the results of scanning electron microscope (SEM), surface area and nitrogen adsorption analysis. The acceleration action of CaCO3 in the decomposition process of talc was demonstrated by the thermogravimetry-differential scanning calorimetry (TG-DSC) test. The pot experiment corroborates that 5 g kg−1 soil Si-OPC application sufficed to facilitate the pakchoi growth by providing nutrient elements. This evidence indicates the prepared Si fertilizer as a promising candidate for Si-deficient soil replenishment. [ABSTRACT FROM AUTHOR]