Statement 1 is correct: Reduced or zero tillage of the land minimises soil disturbance, promoting better water retention. Less disturbed soil creates a more compact surface that reduces evaporation and allows rainwater to infiltrate deeper into the ground.

Statement 2 is incorrect: Applying gypsum before irrigating the field Gypsum (calcium sulfate) is a soil amendment that can improve soil structure and drainage in some situations. However, it doesn't directly conserve water. In some cases, excessive gypsum application might even increase the leaching of nutrients and salts.

Statement 3 is correct: Allowing crop residue to remain in the field Leaving crop residue on the soil surface acts like a mulch. This mulch helps suppress weeds, reduces soil erosion, and minimises water evaporation from the soil surface.