「Feces as sign of something already happened」as LESS OBJECTIONABLE, PREFERABLE TO THE ALTERNATIVE, LESSER OF TWO EVILS since penetrating the vulva and breaking the hymen would have substantially decreased the future sale price of any daughter not a virgin in dynastic China:
　「Viewing women as commodities [see 品] was also made customary from Song Dynasty (960 - 1279) forward, both in the suddenly expanded labor market and within relationships. Men could sell their female kin to slavery or prostitution, and frequently did.」
　　[　https://www.zum.de/whkmla/sp/0910/hersheys/hersheys5.html 2011-04-05　]　
　「In traditional Chinese medicine, there has never been a mental disease called pedophilia (or an equivalent term), or homosexuality, or most of the other so-called sexual variations for that matter. …Children are usually described as natural sexual beings and erotic stimulation and sex-play are seen as beneficial to their healthy development.」
　　[　https://docx2.com/wp-content/uploads/Are-Any-of-the-Pharaphilias-in-DSM-Mental-Disorders_.pdf 2023-05-14　]　
　Nothing in these elements or vocabulary usage requires that the increase referred to is desired or virtuous. Evil often increases and multiplies more quickly than good at times, often by taking advantage of another's disadvantage.
　「Ground, clay, soil」and「tough wall, three generations ago」may depict the ramparts of a castle, or a dam, the former allows a BUILD UP, INCREASE and AUGMENTING of troop strength, the latter of water in a reservoir. Note that the bursting of a dam results in a large gush of various fluids, as the right element also depicts (mucus, blood, feces, and semen perhaps). The bursting of a castle wall allows the rush of troops from both sides in a battle to meet and mix to release a gush of these very same bodily fluids, with mud.
　「Soil three generations ago」used to construct a dam or some other sort of dike, levee, or packed wall might need AUGMENTING due to age and erosion, soil loosening, leaking spurts, crumbling in places, or what have you.
　「Feces as sign of something already happened」suggests that the shit has already hit the fan, or fanatics as it were, so why not INCREASE, AUGMENT, PACK IT IN HARDER AND HIGHER, MULTIPLY, MULTIPLE TIMES, and all that is LESS OBJECTIONABLE since 'hey, it already happened, so what's the harm in adding a little more?'…an excuse given as a pretext.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: variant of 增
Japanese: increase, better, less objectionable, preferable, more, extra, growth, to, to grow, to multiply, still more, to say nothing of, not to mention, still less, to add to, to augment
Unihan extended: increase
EDRDG: increase; add; augment; gain; promote

Used within names (nanori)
まし　･　ます