Which type of soil map is defined as a second order survey?

The correct answer is a general soil map, which is classified as a second order survey. This type of map provides an overview of the soil characteristics across a specific area but does so in a less detailed manner compared to higher intensity surveys. General soil maps are useful for understanding broad soil types and their general distribution, making them suitable for initial assessments of soil-related properties in a region.

In contrast, high-intensity soil maps are more detailed, typically involving extensive data collection and analysis. They offer a finer resolution of soil types and properties, allowing for more specific applications, such as agricultural planning or land use management. Extra-high intensity soil maps take this a step further, providing even greater detail, while custom soil maps are tailored specifically to particular needs or projects, often requiring specific survey protocols. Each of these options serves unique purposes, but only the general soil map aligns with the definition of a second order survey.