How can nitrogen deficiency in plants be identified?

Nitrogen deficiency in plants can be identified primarily by observing that the lower leaves turn yellow and may eventually fall off. This yellowing, known as chlorosis, occurs because nitrogen is an essential nutrient that plants need to produce chlorophyll, the pigment responsible for photosynthesis. When there is insufficient nitrogen, the plant redirects resources from older, lower leaves to support the growth of newer leaves and stems. Consequently, the lower leaves become deficient, leading to their yellowing and premature drop as the plant prioritizes growth in more vital areas.

This characteristic symptom is one of the most common signs of nitrogen deficiency and can help gardeners and landscape architects identify and correct nutrient imbalances in plants effectively. The other symptoms associated with nitrogen deficiency, like stunting or deformation of new leaves, while relevant to other nutrient deficiencies, are not as indicative of nitrogen limitation compared to the yellowing of lower leaves.