मृदा आणि पाणी संवर्धनाचे हे यांत्रिक उपाय आहेत :
(a) ढाळीचे बांध
(b) समपातळीत लागवड
(c) मजगीकरण
(d) समपातळीतील बांध

पर्यायी उत्तरे :

The correct answer is Option C ((d), (c) and (a) only).

Key Points:
• Soil and Water Conservation: Agronomic vs. Mechanical Measures:
• Mechanical / Engineering Measures (यांत्रिक / अभियांत्रिकी उपाय):
• (a) Graded Bunds (ढाळीचे बांध): Engineered earthen embankments constructed across slopes to safely convey excess runoff in high rainfall tracts.
• (c) Bench Terracing (मजगीकरण): Transforming steep hill slopes (16–33% slope) into a series of level bench-like step platforms.
• (d) Contour Bunding (समपातळीतील बांध): Constructing narrow earthen ridges along contours on mild slopes (<6%) to intercept runoff and enhance water retention.
• Agronomic Measures (कृषीविषयक उपाय):
• (b) Contour Cultivation (समपातळीत लागवड): Performing plowing, planting, and harrowing along contour lines (biological/cultural practice, not an engineered earthwork structure).
• Therefore, the purely mechanical measures are (a), (c), and (d) (Option 3).
• Key Takeaway: Contour bunds, graded bunds, and bench terracing are mechanical engineering measures, whereas contour cultivation is an agronomic practice.