Radial engines have been used in cars, helicopters and tanks, as well as other applications. Even on motorcycles, albeit for novelty. I've never flown or driven or worked on any of those installations, so I have no idea how they fare.
I suppose the utility is limited only by the imagination.
Now now, Russian warbirds could be a bit "agricultural", but bearing in mind the whole country was effectively agrarian in nature as late as the 1920s I think they picked things up pretty well - in later years they certainly developed some interesting solutions to rocketry problems that the West relied on brute force to solve.
I flew ag for a number of years, including eastern block aircraft (PZL M18 Dromader). Eastern equipment is very utilitarian. They came with very spartan tool kits, and were largely very simple designs. On the M18, for example, lubrication of all hinge points was external; squirt oil from outside the hinge on flaps, ailerons, etc, and do it as part of the daily walk-around. If the bolt and hinge were dripping, they were lubed.
Their ASz-62IR motor was very tough. We mostly flew turbine conversions, but we also had a number of the radial powered airplanes.
In the ag world, radials have largely fallen out of favor; the weight is replaced by lighter, ore reliable, more powerful turbines, allowing ag airplanes to carry more, go faster to and from the field, and single airplanes to do the work of multiple airplanes. The Bull Thrush, with it's 1820, carried 500 gallons. The current Thrush 660, with it's Pratt PT6A-65 installed, carries nearly eight hundred without the spray booms.
Radial engines were the staple and maintstay of the ag industry for many years, and a lot are still in use on AgCats, Thrush's, etc. By and large, however, few of us truly miss having to sit up all night doing cylinder changes, constantly chasing oil leaks, burned and cut fingers from safetying bolts after replacing cam follower gaskets, or the deafness that came from flying round motors.
Operating round motors takes significantly more skill, attention, and effort than operating turbine engines. A lot of romance is tied to round engines, and they do have their charm. Set aside the glossy magazine shots and the excitement of the airshow, and they were loud, dirty, hot, tempermental engines that required a lot of love, support, and parts. Radials can be a lot of fun, they're neat to watch, and they're still very viable powerplants, but until one has spent the night covered in oil changing out a power recovery turbine or struggling alone on a cold ramp in the dark to get past the kidney sump to a bottom cylinder for a change, or fought 40 knot freezing winds on top of a rickety ladder that's lashed to the engine, in a snowstorm, while swapping jugs, one doesn't really appreciate the realities behind operating those motors.