Deficiency and Toxicity Symptoms for the Essential Element

1. Nitrogen
Deficiency Symptoms: Growth is restricted and plants are generally yellow (chlorotic) from lack of chlorophyll, especially older leaves. Younger leaves remain green longer. Stem petioles and lower leaves surfaces of corn and tomato can turn purple.
Toxicity symptoms: Plants usually dark green in color with abundant foliage but usually with a restricted root system. Potatoes form only small tubers and flowering and seed production can be retarded.
2. Phosporus
Deficiency Symptoms: Plants are stunted and often a dark green color. Anthocyanin pigment may accumulate. Deficiency symptoms occur first in more mature leaves. Plant maturity often delayed.
Toxicity symptoms: No primary symptoms yet noted. Sometimes copper and zinc deficiency occurs in the presence of excess phosporus.
3. Potassium.
Deficiency Symptoms: Symtoms first visible on older leaves. In dicots, these leaves are initially chlorotic but soon scattered dark necrotic lession (dead areas) develop. In many monocots, the tips and margins of the leaves die first. Pottasium deficient corn develops weak stalks and easily lodged.
Toxicity symptoms: Usually not excessively absorbed by plants. Oranges develop course fruit at high potassium levels. Excess potassium may lead to magnesium deficiency and possible manganese, zinc or iron deficiency.
4. Sulfur.
Deficiency Symptoms: Not often encountered. Generally yellowing of leaves, usually first visible in younger leaves
Toxicity symptoms: Reduction in growth and leaf size. Leaf symptoms often absent or poorly defined. Sometime interveinal yellowing or leaf burning.
5. Magnesium.
Deficiency Symptoms: Interveinal chlorosis wich first develops on the older leaves. The chlorosis mays start at leaf margins or tip and progress inward interveinally.
Toxicity symptoms: Very little information available on visual symptoms.