I used to do a fair amount of work with grain farmers (corn, soybeans, wheat) as part of my job.
First of all, other than very small hobby farms, nearly all U.S. farmers do not sell directly to consumers (or if they do, it’s a small part of their business, at farmers’ markets, county fairs, and the like). They are selling to a processor, or (as is the case with dairy farms), they may be members of a co-operative. Either way, they hand off their crops/output to some sort of processor, which aggregates the output from many farms in order to produce what eventually winds up at the grocery store, and on your dinner table.
It may not be “sales skills,” per se, but successful farmers absolutely need a range of business skills. They enter into contracts to sell their crops (in this case, to an ag processing company, like ADM or Cargill), and as the prices of commodities (and in those contracts) go up and down, they have to weigh the cost/benefit to signing a contract today, or waiting to see if the prices go up.
Their materials (seed, fertilizer, etc.) and equipment (tractor, combine harvester, trucks, etc.) can be extremely expensive investments, and again, they have to weigh the cost of purchases versus the anticipated pay-out, or other options. A new variety of corn may have a higher yield, but the seed may be more expensive – will they get their investment back? Do they buy a new combine this year, or keep their fingers crossed that they can get one more year out of it? (A new combine costs about $300K-$500K, and despite the fact that they are only used for a few weeks out of the year, they can wear out in a decade or less.)
Every farmer I dealt with back then was very computer-savvy – they all had PCs in their houses (or barns), and they kept abreast of the contract prices, weather forecasts, etc. on a daily basis (if not even more often). They use GPS extensively, to track yield of their crops when they harvest, and then apply more or less fertilizer in different areas.
Also, most farm operations – even family farms – are bigger operations now than they were generations ago. With grain farming, the farmers pretty consistently told me that, in order to make their investments in equipment pay out, they had to farm a lot of acreage – minimum of at least 1200 acres (typically a mix of land that they actually owned, and land that they rented, often from what used to be other family farms, in which the family still owned the land, but the “farmer” in the family had retired or died).
And, all of that acreage is almost always dedicated to just one or two crops. Some farmers may do a mixture of things: I knew corn farmers who also grew an acre or two of vegetables, for example – but those secondary crops are either (a) a hobby, (b) something to sell at the local farmers’ market, or (c) for the personal consumption of the farmer and his/her family, rather than being a major focus of their business. The old-school idea of a family farm, where one farm might have a couple of dairy cows, some chickens, some vegetables, etc., doesn’t exist in large numbers any more in the U.S.