وسبب وجوب العشر الأراضي النامية حقيقة الريع
The source links ʿushr to land that yields actual agricultural produce.
The relevant analysis concerns productive land and its yield. ʿUshr does not share the identical legal cause with business-wealth zakat or sadaqat al-fitr; those obligations have separately defined structures.
This is why landownership alone, growth or yield, and the timing of the levy must be examined under the rules for agricultural produce rather than by automatically importing all the conditions of zakat on money.