Types

• Not all topsoil is created in the same way. Dark topsoil, for example, is indicative of a great deal of organic matter, which helps plants grow. Lighter-colored topsoil could indicate an absence of organic material and not suit many plants. While drainage is usually good for topsoil heavy in organic material, it also can be good in lighter, sandy soils. Plants suited for one type of topsoil may not do well in other types.
  
  

Depth

• The depth of topsoil can vary greatly among areas. Typical topsoil depths ranges from a few inches to several feet. Below the topsoil is a clay, till and bedrock. Very little, if any, life grows in those areas, which is why it is very important to take care of topsoil and preserve as much as possible. Plants with deep root systems may prefer topsoil with greater depth.
  
  

pH Level

• Topsoil in different parts of the world, or even different portions of the United States, can have very different pH levels. For example, the average soil pH in Florida is about 6.1, which is slightly acidic. In western portions of Iowa, pH could be as high as 9.5. Most plants prefer a soil that is neutral or either slightly acidic or alkaline. In some cases, it may be possible to change topsoil's pH level.
  
  

Plant Choices

• Topsoil acidity, drainage and moisture level combine to affect the types of plants growers choose. For example, blueberries, pines and citrus fruit do better in soil that is acidic. Plants such as asparagus, beech and sagebrush prefer more alkaline soil. Growers test their soil and compare the result to plant profiles to obtain the best idea of what will grow well in their area.
  
  

Problems

• Topsoil can suffer from a number of problems, including compaction and erosion. Compaction is the packing down of soil, which does not allow aeration or water penetration. Erosion is often the result of compaction because water runs off topsoil very quickly, taking topsoil with it. Ensuring that topsoil stays healthy, either through tilling or aeration, is key to avoiding these potential problems.
  
  

Fertilizers

• Growing plants and crops can deplete topsoil of various nutrients, especially nitrogen (N), phosphorous (P) and potassium (K). Growers replenish these nutrients through fertilizers. A balanced fertilizer, which is ideal for many types of crops, is a 2-to-1-to-2 ratio of N-P-K, meaning the fertilizer has twice as much nitrogen and potassium as phosphorous. To optimize conditions, however, growers should test topsoil to learn which nutrients, if any, it lacks.