Question

How is it possible to get a rough idea of the deficiency of an essential element in the soil without doing soil tests?
A. Only by making detailed analysis of the ash of a plant growing in it.
B. By noting the typical symptoms of deficiency shown by plants growing in it.
C. By observing the physical texture of the soil.
D. By determining the dry weight of the plant.

Answer 1

Soil is a mixture of various organic matter, minerals, gases, and microorganisms. It covers the top layer of the earth’s surface. It is essential for the growth of plants and hence supports the life of humans and animals.

Complete answer:
Essential elements in soil are required for the growth of plants. Essential elements present in soil are nitrogen, phosphorus, potassium calcium, magnesium, sulfur, iron, copper, zinc, magnesium, molybdenum, boron, and chlorine. Plants obtain these elements from the soil. If any of the minerals is deficient in the soil, it is reflected in the plants as a disease or as a deficiency. Thus, it is clear that by noting typical symptoms of deficiency shown by plants growing in it can be used to determine the deficiency of an essential element in the soil.
Let’s study the effects of deficiency of some nutrients on plants:
Phosphorus: deficiency of phosphorus in soil can lead to impaired vegetative growth, weak roots, low yield.
Potassium: plants deficient in potassium are more susceptible to disease as they are unable to utilize the nitrogen. It usually appears on the lower leaves of the plants such as chlorosis (yellow leaves) followed by necrosis (death).
Calcium: lower levels of calcium in soil lead to necrosis of tissues in plants, stunted growth of the plant and curling of young leaves
Magnesium: deficiency of magnesium leads to interveinal chlorosis especially in lower leaves and slow growth of the plants.
Sulfur: deficiency of sulfur in soil leads to slow growth of plants, necrosis of plants at young age.

Thus, the correct answer to this question is option-(B).

Note: Just as some nutrients are important for soil, some are harmful, too, such as lead and aluminum. Elevated levels of aluminum can be toxic for roots of the plants and would not allow the plant to grow. It also reduces phosphorus solubility. Similarly, elevated levels of lead are harmful for soil, too.