Kshetra is something quite different from Kshetrajna. Kshetra is Unmanifest. The Soul, which is above the twenty-four principles, is called the Knower.
अन्यदेव च क्षेत्रं स्यादन्यः क्षेत्रज्ञ उच्यते। क्षेत्रमव्यक्तमित्युक्तं ज्ञाता वै पञ्चविंशकः॥