Shikantaza, or "just sitting" meditation, is a form of meditation practiced in Soto Zen Buddhism. It is a simple and direct method of meditation that involves sitting in a relaxed and upright posture, with a clear and open mind. The focus is on being present in the moment, without any specific object of meditation.

One of the unique aspects of shikantaza meditation is its emphasis on non-duality, or the idea that there is no separation between the meditator and the object of meditation. This means that there is no need for a specific technique or object to focus on during meditation. Instead, the practitioner simply sits and allows their mind to be present without trying to control or manipulate it in any way.

Given this approach, it is possible to combine shikantaza meditation with other forms of meditation. In fact, many practitioners of Soto Zen Buddhism incorporate other forms of meditation into their practice, such as walking meditation or chanting. However, it is important to keep in mind that the focus of shikantaza meditation is on simply being present in the moment, without any specific object or technique. Therefore, any other forms of meditation should be approached with the same open and non-dualistic mindset.

It is also worth noting that shikantaza meditation is not a passive form of meditation. While the practice involves sitting and being present without any specific goal or object, it is still an active and engaged form of meditation. The practitioner is actively observing their thoughts and experiences without judgment or attachment, and this requires a certain level of mental discipline and focus.

Incorporating other forms of meditation into shikantaza practice can be beneficial in providing variety and helping to deepen one's understanding of the present moment. However, it is important to approach these other forms of meditation with the same open and non-dualistic mindset as shikantaza. This means not becoming attached to any particular technique or object, and being willing to let go of any expectations or preconceived notions.

In conclusion, while shikantaza meditation is a distinct form of meditation, it can be combined with other forms of meditation as long as the practitioner maintains the same non-dualistic and open mindset. Incorporating other forms of meditation can provide variety and deepen one's understanding of the present moment, but it is important to not become attached to any specific technique or object. Ultimately, the focus of shikantaza meditation is on being present and engaged in the moment, without any specific goal or object.