• 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

• Salt-Affected Soils in Maharashtra:
• In Maharashtra, salt-affected soils occur extensively across three distinct physiographic and agro-ecological regions:
• Saline Soils: Extensive inland salinity in the vertisols of the Purna Valley (Vidarbha region) and the canal command tracts of Western Maharashtra due to deep waterlogging.
• Alkali (Sodic) Soils: Widespread in black cotton soil basins where high exchangeable sodium percentage ($ESP \gt 15\%$) causes clay dispersion and severe impermeability.
• Coastal Saline Soils: Locally termed Khar lands, covering over 65,000 hectares along the Konkan coastline (Thane, Raigad, Ratnagiri, Sindhudurg) subject to marine tidal ingress.
• Conclusion: (A), (B) and (C) (Option 4).

Correct option: (4) (A), (B) and (C).