Chinese land measure, fields
畆 centers on a traditional Chinese unit of land area, roughly equivalent to a field or plot. The meaning extends naturally to fields in general.
畆 is a variant form of 畝, which historically combines 田 (field) with a phonetic component. The exact development of the right-side 厶 is uncertain, but it likely represents a simplified or corrupted phonetic element.
The left side 亩 looks like a field with a measuring line over it, and the right side 厶 resembles a small private marker. Picture a field divided into measured plots with boundary markers.
For ボウ, imagine a farmer bowing to the measured field: bow -> ボウ, as they respect the land.