The figure shows the two crop fields [Plots A and B] have been treated with manures and chemical fertilizers respectively, keeping other environmental factors the same. Observe the graph and answer the following questions:
(i) Why does plot B show a sudden increase and then a gradual decrease in yield?
(ii) Why is the highest peak in plot A graph slightly delayed?
(iii) What is the reason for the different patterns of the two graphs?
Manures:
(i) 1. The addition of chemical fertilizers causes a rapid rise in yield due to the rapid release of nutrients such as N, P, K, and others.
2. The graph's progressive fall could be attributed to the constant use and excessive quantity of pesticides, which kill bacteria important for rebuilding organic matter in the soil.
3. This reduces soil fertility.
(ii) 1. Manures provide tiny amounts of nutrients to the soil slowly because they include a lot of organic matter.
2. Soil organic matter increases the soil's ability to store and supply vital nutrients (such as nitrogen, phosphate, potassium, calcium, and magnesium) as well as retain harmful substances.
3. It permits the soil to adapt to changes in soil acidity and aids in the decomposition of soil minerals.
4. It consistently improves soil fertility by enriching it with nutrients.
(iii) The difference between the two graphs indicates that manure application is favorable for long-term cropping since yield tends to remain high as manure quantity grows.