There are various types of soil sampling and soil sampling basically helps in quantification of the soil content as well. These types of soil sampling can be used for different purposes- they could be used in order to determine whether or not site would be good enough for construction purposes or if certain types of trees and plants can be grown here. You know how there are parks where certain types of plants are grown? Prior to the plantation of these types of plant, certain types of soil sampling are carried out to judge whether or not the site is suitable for that particular type of plant.
Random sampling is one of the many types of soil sampling where the researcher would take samples from different points at random in able to quantify the soil and to be able to determine if it is suitable for a certain purpose or use. This is one of the more general types of soil sampling- that means that it is done in order to get a general idea of what the soil at a site is like. These may be done to determine if the soil is usable for a number of reasons.
Then there is grid sampling. What happens in these types of soil sampling is that soil at a site is divided into many sections and each one these sections is studied in order to determine how useful the site would be for a certain purpose. In some cases this may be done in order to determine whether or not different types of plants and/or crops can be grown on the site. The thing about this is that it gives a clearer picture as to the nutrients density of the soil which enables the researcher to determine the kinds of plants that can be grown here.
Topographical unit is one of the other many types of soil sampling methods that are used in some areas. However, as the title of this form of sampling suggests- it helps get a clearer idea on the nutrient content in the soil from one place to another. Sometimes the soil nutrient content may differ from one spot to the next on the same site and this is usually due to topographical reasons. For example, some areas of a site may be richer in the nutrient content of soil because they are close to the river and rivers are known to consist of silt which enriches the soil. Other spots may be less rich in some nutrients because they are further away from these. Interestingly both can be found on/in the same site and as a result one may be able to grow some types of crops on the enriched areas whereas other types of crops may be grown in other areas on the same site.
These are some types of soil sampling though there are many others that even geologists use in order to determine how old a certain site or place may be as well.