perchenia-

Plough is a very conservative word. Plowing is a heavy-duty, deep-soil process designed to break hard crusts and invert the earth, whereas tilling is a shallower, refining process used to pulverize the topsoil, control weeds, and blend in fertiliser or compost. Sindarin already has a word for the verb "till", "barna-", so it's necessary to create a new verb for "plough". I found very few languages with etymologies which can reconstruct a descriptive meaning, the best example I think is Japanese. "Tagayasu" 耕す, "to till, cultivate, plough", composed by "ta" 田 "cultivated field" and "kaesu" 返す "turn back, reverse, turn over", effectively means "to turn over the field". Since most languages have a word for "plough", I've used roots to create the neologism, to preserve it's antique character. The noun "plough" uses the instrumental suffix, and the verb "plough" uses the causative.