Common Nutrient Deficiencies in Vegetable & Fruit Plants

Container Gardening for Health: The 12 Most Important Fruits & Vegetables for Your Organic Garden
Organic gardening is different from traditional gardening in its focus on creating healthy soil. When soil is nutrient rich, plants grow quickly and are better able to withstand pest and disease stress.
Nitrogen is necessary for photosynthesis, cell growth, and reproduction. This is the element plants use in greatest amounts. Plants deficient in Nitrogen may have yellow leaves and poor growth. Adding organic matter, such as aged manure, cottonseed, and composted plant materials will improve nitrogen levels in the soil.
Phosphorousis required for cell growth, plant reproduction, and flower and fruit formation. Plants deficient in Phosphorous will be stunted, a purplish tinge on the underside of their leaves (yellow leaves in the final stages), poor flowering and poor fruiting. Amend deficient soil with bone meal or rock phosphate.
Potassium is necessary for formation of flowers, leaves, and fruit. It plays a role in photosynthesis in low light conditions and in plants' water regulation. Potassium deficiency occurs most commonly in sandy and acidic soils. Amend deficient soil with kelp or seaweed.
Calcium strengthens stems and other plant parts. Calcium deficiency begins with yellowing and progresses to browning of young leaves. Calcium deficiency is responsible for blossom end rot in tomatoes and tip-burn in lettuce. Amend deficient soil with eggshells and oystershells.
Magnesium is crucial for photosynthesis. It also aids in the action of nitrogen, phosphorus, and sulfur. Magnesium aids in cleansing plants of natural metabolic waste. It assists in the formation of proteins. First symptoms include the discoloration of veins in the lower leaves. Leaves may also become thin and brittle and may cup upward. Amend soils deficient in Magnesium with Epsom salts, Fishmeal, or Greensand.

Other Nutrient Deficiencies discussed in the book include Iron, Zinc, Boron, and Copper.
Container Gardening for Health