Question

Which of the following is not true for fertilizers?
A. They increase the yield
B. Their excessive use disturb the balance of nutrients in soil
C. They are generally used in small quantity
D. They are environment friendly

Answer 1

Fertilizers are chemical substances supplied to the crops to increase their productivity. Fertilizers are natural or artificial substances which contain chemical elements that improve growth, development and reproduction in plants.

Complete answer:
Option A: Fertilizers are natural or artificial substances which contain chemical elements that improve growth, development and reproduction in plants. This statement is true.Therefore, this is the incorrect option.
Option B: Treatment with fertilizer introduces chemical elements present in fertilizers to the soil. It adds to the fertility of plants or replaces the chemical elements used up by previous crops. Excessive use of fertilizers will disturb the balance of nutrients in soil, which can lead to negative effects on the crops. This statement is true.Therefore, this is the incorrect option.
Option C: Fertilizers are concentrated with nutrients and the amount to be supplied to a given quantity of soil or given number of crops should be calculated accordingly. Use of too much fertilizers can kill the crops, therefore they are used in small quantities.This statement is true.Therefore, this is the incorrect option.
Option D: The excess nutrients from fertilizers are known to cause environmental pollution in many ways. Fertilizers are not environmentally friendly. Therefore, this is the correct option

The excess nutrients run off to the water bodies and accumulate there. This often poisons aquatic life. Also, they cause algal blooms,the death and decomposition of which will eventually lead to the removal of oxygen from water.This is known as eutrophication or death of the water body.
Also the non biodegradable components of fertilizers get absorbed by plants, and through the food chain they get accumulated in each trophic level. This process is called biomagnification.

Hence, the correct answer is option (D)

Note: Chemical fertilizers include one or more of the most important elements for plants, which are nitrogen, phosphorus and potassium. Sulphur, magnesium and calcium are elements of secondary importance.
Fertilizers increase the water retention capacity of the soil.