Which of the following is true about sawdust as a substrate?

Sawdust as a substrate is often valued for its properties that support plant growth, particularly because it has a structure similar to that of bark. Both sawdust and bark are organic materials that can improve soil aeration and drainage, while also providing a habitat for beneficial microorganisms. The similarity in their physical properties can make sawdust a suitable alternative to bark in various growing systems, allowing it to retain moisture while still providing adequate drainage.

In contrast, sawdust is generally not considered very expensive when compared to other substrates. Additionally, while it does decompose over time, it does not do so as quickly as some other organic materials; hence, it can be beneficial for longer-term use in containers. Lastly, sawdust typically has a lower nitrogen content, which contrasts with the options that discuss nitrogen, making it less suited for roles that require high nitrogen availability for plant growth.