Conserving anything means to make use of it in a wise manner so as to preserve the destruction of it to the extent that it is no longer available for use or cannot be used anymore. When we refer to different types of soil conservation methods we are talking about the methods used in order to prevent soil from being eroded on a daily basis so that the soil can be used in future as well. Since people use soils in different ways, most soils are now getting leached of their nutrients and important qualities which means, less food resources in the future.
Crop rotation is one of the oldest and many types of soil conservation methods that is still used to date. What farmers do is that they may divide the area into different parts. So, one piece of land, with different types of soils would be divided, into parts according to the nutrients and the soil quality. At one point they may decide to grow wheat and barley on A, cotton and sugar cane on B and say, rice on C. D would be left empty because it will have already been used and this way D can regain its qualities. It is given time to regain the nutrients it has lost. The way the crops are grown later would be different, then and the farmer would use lands B, C and D and leave A empty for the same reason as they left A empty initially.
Contour bunding is also one of the many types of soil conservation methods. What happens sometimes is that water run off erodes the soil by stripping the top layer of the soil and leaching it of very important nutrients. This often happens in landslide. What bunding does is that it helps conserve the soil by preventing the top layer of the soil from getting eroded in this way. Landslides often strip the soil of important nutrients and bunding helps ensure that this does not happen. This way the soil is not eroded and it is protected against all sorts of water run off at all times.
Another thing that is done is to plant cover crops. These types of soil conservation methods ensure that the top layer of the soil is protected against erosion (wind or water erosion) by using unused land. This way organic matter can build up and become part of the soil so that it can be used for other crops later on.
Bench terracing is also one of the many types of soil conservation methods and what happens here is that the soil is literally made into terraces. Each “step” of the terrace is used to grow a different type of crop. Think of it in terms of budgeting. You decide how much money to spend on what part of your life, for example. Bench terracing is similar in the sense that it helps you determine what crop you want to grow where on the soil. The unused part is conserved.