Fertilizer burn is associated with which condition?

• A. High salt concentrations in soil causing water to move out of roots into soil
• B. Excess nitrogen causing rapid growth
• C. Low soil pH causing aluminum toxicity
• D. Waterlogged soil causing root suffocation

Answer: (A)

Fertilizer burn occurs from osmotic stress caused by high salt concentrations in the soil. When fertilizer salts raise the soil’s salinity, the water potential of the soil solution becomes higher than that inside the plant roots. Water then moves out of the root cells into the soil to try to balance the osmotic difference, leading to dehydration of root and shoot tissues and symptoms like leaf scorch. That makes the statement about high salt concentrations in soil causing water to move out of roots into the soil the best description of fertilizer burn.

Other scenarios involve different problems: excess nitrogen can drive rapid growth and other stress responses, low soil pH can cause aluminum toxicity, and waterlogged soil limits oxygen to roots. None of these describe the osmotic/solutal cause of fertilizer burn as directly as salinity does.