Subtopic: Salt-Affected Soils and Land Reclamation
Question Statement:
According to the USDA Salinity Laboratory, the leaching requirement ($LR$) for steady-state root zone salinity management with irrigation water salinity $EC_{iw}$ and maximum permissible drainage water salinity $EC_{dw}$ is expressed as:
Options:
(A) $LR = \frac{EC_{iw}}{EC_{dw}}$
(B) $LR = \frac{EC_{dw}}{EC_{iw}}$
(C) $LR = EC_{iw} - EC_{dw}$
(D) $LR = EC_{iw} \times EC_{dw}$
Answer Key:
A
Step-by-Step Solution & Explanation
By steady-state salt mass balance (salt applied = salt leached: $D_{iw} EC_{iw} = D_{dw} EC_{dw}$), leaching fraction $LR = D_{dw} / D_{iw} = EC_{iw} / EC_{dw}$.