aciemar

A regional verb from Álava, La Rioja, and Soria in northern Spain meaning to spread manure/fertilizer on a field (estercolar), or in some local uses, to perfect something down to the last detail. Extremely rare outside those areas.

• Los labradores aciemaban el campo antes de la siembra. — The farmers spread manure on the field before sowing.
• En esa comarca todavía se dice 'aciemar' por estercolar. — In that region, 'aciemar' is still used to mean spreading manure.
• Aciemó cada detalle del proyecto hasta dejarlo perfecto. — He perfected every detail of the project until it was flawless.

It's a narrow regionalism from northern Spain — estercolar or abonar are what the rest of the Spanish-speaking world says for fertilizing a field.