Boron toxicity may occur if irrigation water of fertigation solution exceeds 0.5 to 1.0 mg/L, particularly with long-term exposure in slow-growing crops.

Chloride may occur naturally in water supply or from contamination (e.g. road salts, gas well drilling, etc.). Chloride can impact plants from excessive foliar absorption or root uptake. Most plants can tolerate levels as high as 100 mg/L, but levels above 30 mg/L may cause problems for sensitive plants.

Levels as low as 0.2 mg/L can be toxic to some plants. Typically originates from corrosion of copper plumbing.

Concentrations >0.3 mg/L can result in clogging of irrigation equipment. Levels >1.0 mg/L may cause foliar spotting with overhead irrigation. Levels >5.0 mg/L can cause severe staining and toxicity in sensitive plants.

Concentrations >0.05 mg/L can cause staining and result in clogging of irrigation equipment. Levels >2.0 mg/L may be toxic to sensitive plants especially if the pH of growth media is low.

Levels >0.05 mg/L can be toxic to plants.

High levels of sulfur are rare, but may be elevated in coal mining regions. Where sulfur levels are <10 mg/L, sulfur may need to be included in the fertilizer program for greenhouse production.

Sodium may originate from road salt, wastewaters, or water softening wastes. Levels in excess of 50 mg/L may cause toxicity in sensitive plants, particularly in recirculating irrigation systems. Problematic sodium levels may be further diagnosed by evaluating the relative concentrations of sodium, calcium, and magnesium, referred to as the Sodium Adsorption Ratio (SAR). A SAR of <2.0 is considered safe for most plants, especially if sodium is <50 mg/L.