Nitrogen deficiency

[2] Some symptoms of nitrogen deficiency (in absence or low supply) are given below : Plants look thin, pale and the condition is called general starvation.

[4] Nitrogen deficiencies also cause leaves to remain small, and drop prematurely, resulting in less photosynthesis occurring in the plant, and fewer, smaller tubers can form for harvest.

Research done by Yara International has shown that there is a direct correlation between tuber size and yield, and the amount of plant-available nitrogen in the soil.

Symptoms include poor plant growth, and leaves become pale green or yellow because they are unable to make sufficient chlorophyll.

[8] However, these physical symptoms can also be caused by numerous other stresses, such as deficiencies in other nutrients, toxicity, herbicide injury, disease, insect damage or environmental conditions.

Therefore, nitrogen deficiency is most reliably detected by conducting quantitative tests in addition to assessing the plant's visual symptoms.