Depends on your definition of "improvements".
The short answer (in Tennessee) is nothing.
For nearly all of TN, no matter what you do (with free range deer herds here) you are not going to have many bucks gross over 150 no matter how long they live.
Look at the 18,000 acre Ames Plantation.
After decades of really good deer & trophy buck management,
how many bucks over 150 were killed?
Can they be counted on one hand or two hands?
Whether TN hunters want to believe this or not, this remains the reality of free-roaming TN deer herds. Again, look at the Ames Plantation, where there is lots of agricultural fields, great habitat overall, and above average soils for TN.
Personally, I've been involved with deer management now on thousands of acres for decades (most particularly in Stewart Co., TN). No matter how much someone may want to convince you otherwise, you cannot get blood from a turnip. And you need, imo, at least 5,000 contiguous acres under "trophy" buck management to prevent mostly your neighbors from reaping the benefits of your intense management. Rutting bucks are going to roam, and even with 5,000 contiguous acres, "your" bucks may spend more of their time (during the rut) on other people's properties.
While I agree areas containing big agricultural fields may increase antler scores by 5 to 15 points (that's might turn an average 120-class MATURE buck into a 130-class one), your single best way to grow larger antlered older bucks is simply do not kill your largest antlered 2 1/2 & 3 1/2-yr-old bucks!
What we're talking about is letting a 115-130-class 2 1/2 to 3 1/2-yr-old buck "walk". While a few hunters can & do regularly do this, it's a very tall order for most hunters. This is in part because these young bucks (with above average antler genetics) have antler APPEARING much larger than their reality. This is due to the bucks not being old enough to have completely grown their skeletal systems (i.e. small bodies make average antlers appear larger).
Consequently, hunters' antler high grading becomes the #1 obstacle to producing more larger antlered mature bucks. You may personally stop shooting your best stock, but it's usually unreasonable to expect all the other hunters within 5 miles of your hunting area to do this as well. And it only takes one other hunter a couple or 3 miles away to kill a particular promising young buck you and your friends may have let walk.