Software engineering can be self-studied very cheaply, lots of free resources, mostly you just need time and motivation. Failure is usually cheap.
Farming on the other hand requires more local, implicit and hands-on knowledge, capital requirements are high, feedback cycles are slower and failure is expensive.
It’s much more difficult than software engineering, in every way.
There might be an argument for cost at the highest scale in each field which few in either profession really make it to but I'd bet even then its pretty on par.
I've been a huge fan of comparing the complexity or cost of a profession. We as a species specialize because doing these tasks in the most efficient way requires managing large number of details that are not obvious at first glance.