• Leaching Requirement (LR) in Salinity Management:
• The Leaching Requirement ($LR$) is the fraction of applied irrigation water that must pass through the crop root zone to prevent soil salinity from exceeding a specified threshold:

where:

• $D_d$ = depth of drainage water percolating below root zone
• $D_i$ = depth of applied irrigation water
• $EC_{iw}$ = electrical conductivity of the irrigation water
• $EC_{dw}$ = electrical conductivity of drainage water at bottom of root zone
• Conclusion: Option 1.

Correct option: (1) Option 1