Explanation:

Ploughing up and down the slopes will not help in soil conservation. Let us understand why this is the case:

Contour ploughing:
- Contour ploughing involves ploughing furrows along the contours of the slope.
- This helps in reducing the speed of water runoff and prevents soil erosion.
- The furrows act as a barrier, trapping the water and preventing it from flowing downhill rapidly.
- This method helps in conserving the topsoil and retaining moisture in the soil.

Strip cropping:
- Strip cropping involves cultivating crops in alternating strips or bands across the slope.
- The strips of different crops act as barriers, preventing the flow of water and reducing soil erosion.
- The crops also help in holding the soil together with their roots, preventing it from being washed away.
- This method helps in conserving the soil and reducing erosion.

Creating shelter belts:
- Shelter belts are rows of trees or shrubs planted along the edges of fields or slopes.
- These belts act as windbreaks, reducing the speed of wind and preventing soil erosion.
- They also help in reducing the impact of heavy rain and protecting the soil from being washed away.
- The trees and shrubs also provide additional benefits such as providing shade, habitat for wildlife, and improving the overall microclimate.

Ploughing up and down the slopes:
- Ploughing up and down the slopes refers to ploughing along the gradient of the slope instead of across it.
- This method increases the length of the slope exposed to erosion by water runoff.
- It leads to the formation of furrows that act as channels for water to flow downhill.
- Ploughing up and down the slopes accelerates soil erosion and increases the risk of soil loss.
- It is an unsustainable practice that should be avoided to conserve the soil.

Therefore, ploughing up and down the slopes will not help in soil conservation. Instead, it will contribute to soil erosion and loss of topsoil, which are detrimental to agricultural productivity and the environment.