Question

Following figure shows the two crop fields (Plots $A$ and $B$) have been treated by manures and chemical fertilisers respectively, keeping other environmental factors same. Observe the graph and answer the following questions.​
(a) Why does plot $B$ show sudden increase and then gradual decrease in yield?​

Answer 1

• With addition of chemical fertilisers there is sudden increase in yield due to release of nutrients $N$, $P$, $K$ etc. in high quantity which are absorbed by the roots quickly. ​
• The gradual decline in the graph may be due to continuous use and high quantity of chemicals which kill microbes useful for replenishing the organic matter in the soil. ​
• This decreases the soil fertility.​