Sodium Adsorption Ratio (SAR) is a critical factor in irrigation water quality, as it affects soil structure and fertility. High SAR values can lead to soil dispersion, reducing its water infiltration rate and increasing erosion. This can result in decreased soil fertility, as nutrients are washed away, and reduced crop growth. Furthermore, high SAR can also cause calcium and magnesium ions to be displaced by sodium ions, leading to soil degradation and reduced soil aeration. Managing SAR levels in irrigation water is crucial to maintaining healthy soil structure and fertility.