Too Much Phosphorus

• Zinc is one of the required micronutrients for plants.Jupiterimages/Photos.com/Getty Images
  
  Toxic levels of phosphorus in the garden prevent plants from absorbing and using other needed micronutrients, even when those nutrients are present in the soil in sufficient amounts. The most common micronutrients affected for plant use are zinc and iron.
  
  

Symptoms

• Chlorosis is a yellowing of the leaves often caused by iron deficiencies.Goodshoot/Goodshoot/Getty Images
  
  Symptoms of plants with phosphorous toxicity present as deficiencies in iron and zinc in the younger foliage. Iron deficiencies cause a yellowing of the leaf while maintaining green veins. Zinc deficiencies present as a bleached appearance to the younger foliage.
  
  

Remediation

• A laboratory analysis of your soil is a quick test for phosphorus toxicity.Jupiterimages/Comstock/Getty Images
  
  The only way to know for sure if the levels of phosphorus in a garden are too high is to have the soil analyzed. If the results reveal that there is indeed too much phosphorus, the only remedy is to cease all fertilizer applications that contain phosphorus and wait for the levels to drop back to normal over time.