A description or derogatory for someone easy going, unskilled or useless.

It originates from the fact that Buckwheat is a crop that is extremely easy to grow in most climates and in even the poorest soil, hence requiring less skill from the farmer than more demanding crops.
Further Buckwheat is often used to condition soil for other crops, so the farmer really should be able to grow other primary crops in the conditioned soil, given that the farmer is active and skilled.
An alternate origin could be the black character in "The Little Rascals" series named Buckwheat who became synonymous with the picaninny character, attributing the characteristics of black/picaninny stereotype mixed with the word farmer to suggest that someone works with the skill and efforts of a picaninny stereotype.
"Go out and fix it you buckweat farmer"

"Don't let him do the job he is a buckwheat farmer"
by Sohave December 31, 2019
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