# Usage of Si, P, Se, and Ca Decrease Arsenic Concentration/Toxicity in Rice, a Review
### Phosphorus (P) and As
Unlike hydroponics, P usage in the soil increases arsenic uptake by the plants because of arsenic excretion [67]. Due to the essential role of phosphate in controlling the solubility of arsenic in the soil and its uptake through plants, special attention to P in paddy fields should be given [68]; in addition, the simultaneous usage of calcium and phosphorus forms the Ca-P-As complex and reduces mobility in enriched soils, [69]. Because As and P interactions in the soil-plant system are complicated, most studies have failed, while the variability competition between P and As depends on substrate conditions and soil type [70, 71, 72]. The much higher application of P may help compete for arsenic uptake in plants. In contrast, increasing the concentration of arsenic with increasing P in the soil solution may also increase arsenic toxicity because of As excretion in the soil solution. On the other hand, excessive P usage for the plants may also enhance the environmental risks [73]. For example, triple superphosphate (TSP) is vital among the phosphorus fertilizers, and the raw material of TSP, phosphate rock, may contain arsenic and release arsenic from solid soils into the soil solution [65]. At similar concentrations of P and As, arsenic is more available for uptake by the plants because of the smaller size of arsenic, and the charge of P ions binds to the soil with a higher intensity than As (V) [64,74]. In addition, P competes with As (V) over time because of the lower soil uptake of P, and according to the stock charge hypothesis, ligand exchange theory, and Steindorf-Rehbon-Shintoch equation, Pi is more likely to be replaced by As (V) in soil [64,75]. Soil properties, soil texture, soil mineralogy, and environmental factors may have a significant impact on soil availability, mobility, and interaction of As-Pi [76], and uptake through plants, including mineral components, the presence of anions (e.g., microbial activity, organic matter (OM), redox potential, citrate, phosphate, pH, phytates/phytic acid, and in particular, iron oxide and Al oxide/hydroxides) [77,78]. Amid these factors, pH and goethite firmly control the behaviour of P and As. Iron and magnesium-rich minerals such as phronesis smectites, nontronite, goethite, bronchitis, and pyrolusite absorb more As (V) than Pi when prepared in molar ratio. However, Pi absorbs more than As (V) in non-crystalline allergens containing allophane, boehmite, gibbsite, and clay sections (e.g., vermiculite, illite, and kaolinite) [79,80]. Goethite's high levels in the soil can decrease P and As uptake by plants. Adding Fe and P to high arsenic soils using a sequential combination method can reduce arsenic toxicity to plant roots by providing a food source [81,82]. In the presence of sandy soils and sandy loans, with P, due to the low uptake of As (V) ions, they are displaced from the surface of the sand and increase the uptake of arsenic by plants, and as a result, this reduces plant growth. However, arsenic absorption and toxicity are reduced in sandy loam, silty loam, and clay loam soils [83,84,85]. High supply P can severely change arsenic solubility and mobility in alkaline or anion-fixing soils [80]. The adsorption and desorption of Pi and As (V) have similar properties and follow the [PERSON] and Freundlich equations in high pH (calcareous purple), neutral, and low pH (acid) soils, but because of mobility and dissolution, and non-reactivity of P at low pH are not always interdependent--the main difference between the two models is that [PERSON] assumes that ions are adsorbed as a monolayer on the surface, and maximum adsorption occurs when the surface is completely covered, while [PERSON] assumes heterogeneous surfaces with which it has different affinities that have multi-layered adsorption [74,86,87]. Therefore, phosphate fertilizers, the concentration of As, and soil properties in the soil solution are the most critical factors that control the absorption of arsenic by rice in soils contaminated with As [73] (Table 2).