Topsoil
Topsoil
Topsoil is the upper, outermost layer of soil, usually the top 2 inches (5.1 cm) to 8 inches (20 cm). It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs.
Classification
In soil classification systems, topsoil is known as the "A Horizon," therefore, it is the very top layer.[1]
[edit]Evaluating Topsoil
The two common types of Topsoil are Bulk and Bagged Topsoil. The following table illustrates major differences between the two. [2]
| Topsoil Type | HM% | BS% | pH | P-I | K-I | Ca% | Mg% |
|---|---|---|---|---|---|---|---|
| Bulk | 0.3 | 69 | 5.2 | 009 | 026 | 45 | 10 |
| Bagged | 0.7 | 78 | 5.8 | 166+ | 178 | 56 | 12.3 |
When starting a gardening project, it is very crucial to check whether or not the Soil is satisfactory. Following are the desired levels of Topsoil nutrients. [3]
| Category | Desired Results |
|---|---|
| pH Level | 5.8 to 6.2 |
| Phosphorus (P-I) | Index of 50 |
| Potassium (K-I) | Index of 50 |
| Calcium (Ca%) | 40-60% of Cation Exchange Capacity (CEC) |
| Magnesium (Mg%) | 8-10% of CEC |
| Base saturation (BS%) | 60-80% of CEC |
| Manganese (Mn-I) | Index > 25 |
| Zinc (Zn-I) | Index > 25 |
| Copper (Cu-I) | Index > 25 |
Time in Riyadh 
at any time
