Years ago there was a video shared here and elsewhere of Dr. Albert Bartlett at the university of colorado boulder, called "the most important video you'll ever see": https://www.youtube.com/watch?v=F-QA2rkpBSY

involving the exponential function.  the rule of 72 is a way of converting a% yearly growth into the time it takes to double.  for example 72/4% growth is 18 year doubling time.

an exponential function is like a mirage on a chart where the line starts horizontal and turns vertical, but it always looks the same, no matter where in history you are because you always change the chart increments over time to reflect the past and the future and fit in the graph.  its like walking on a trampoline in that no matter where you step, you are at the lowest part and everywhere else slopes up.

another important attribute is that all the growth of all the doubling times (no matter how many periods of doubling) is one less than the next doubling time.  

where am I going with this?  farms and businesses operate like an exponential function if they grow every year.  at 10% growth, doubling time is 7.2 years.  That means at 10% growth year over year, the last 7.2 year of a farmers life should equal all the prior 7.2 year periods added together.

at 6% growth, again using the rule of 72/6 = 12 year doubling time.  If a farmer retires at age 72, he would (at a 6% growth) double the value of the farm compared to when he was 60, quadruple of when he was 48, 16x of age 32, and 32x the value of when he was 20.   If he can farm til hes 84, he could double all of these numbers again, but wont get to spend much of it lol.

So if you are a beginning farmer, just remember this rule, and remember steady growth and doubling time.  and you'll realize why old farmers and widows own so much farmground and it seems so hard to get started.  It also shows why a multi generation farm can grow so large.

steady growth seems horizontal starting out, (like you aren't getting anywhere) but will get you where you want to go.