What is a characteristic of both rotary and drop spreaders in granular application?

In the context of granular application, both rotary and drop spreaders are designed to deliver materials evenly across a surface, and they operate by gravity feed mechanisms. This allows the spreaders to have adjustable openings that control the flow of the granular product being applied. The capability to adjust these openings is essential as it enables the applicator to modify the application rate based on the specific requirements of the task at hand, such as the type of granular material and the area being treated.

This characteristic distinguishes these spreaders from others that may use different mechanisms or are intended for different types of applications. It's also important to note that while they have similarities, rotary spreaders disperse the product in a broader swath, while drop spreaders release materials directly below the spreader, providing precision in application.

In contrast, the other options do not accurately describe the common characteristics of both types of spreaders. For instance, they are not used for liquid applications; they do not inherently require constant manual monitoring; and they can be used in various weather conditions, not solely dry weather.