Leaching requirement can be estimated by formula

Answer: Option A

Leaching is the process of loss of soluble substances and colloids from the top layer of soil by percolating precipitation.
In agriculture, leaching is the loss of water-soluble plant nutrients from the soil, due to rain and irrigation.
The leaching requirement of any soil can be estimated by the formula:
$$\text{LR}=\frac{\text{E}{\text{C}}_{\text{iw}}}{\text{E}{\text{C}}_{\text{dw}}}$$