Subtopic: Leaching requirement and salinity control
Question Statement:
The leaching requirement ($LR$) for maintaining permissible root zone salinity using irrigation water of electrical conductivity $EC_{iw}$ and drainage water electrical conductivity $EC_{dw}$ is given by:
Options:
(A) $LR = \frac{EC_{iw}}{EC_{dw}}$
(B) $LR = \frac{EC_{dw}}{EC_{iw}}$
(C) $LR = \frac{EC_{iw}}{EC_{iw} + EC_{dw}}$
(D) $LR = 1 - \frac{EC_{iw}}{EC_{dw}}$
Answer Key:
A
Step-by-Step Solution & Explanation
By steady-state salt balance:
$\text{Salt applied} = \text{Salt removed}$
$D_{iw} \cdot EC_{iw} = D_{dw} \cdot EC_{dw} \implies \frac{D_{dw}}{D_{iw}} = \frac{EC_{iw}}{EC_{dw}}$
Where $\frac{D_{dw}}{D_{iw}}$ is the Leaching Requirement ($LR$).