Yes, at a very high cost in money and time you can extend the life of a plot by a few years, but nature abhors a monoculture. When a monoculture is growing year after year, all of the plants are extracting the same nutrients out of the soil (micro as well as macro) and putting the same nutrients back into the soil. Eventually the soil just wears out. You can fight it with herbicides year after year and try to make things look pretty like on the TV food plot shows if you want but it is a loosing battle.
There are even tricks I play with herbicides on occasion if I don't have time to rotate when I really should. If I take an old well established clover plot, say 6 or 7 years old for ladino, that is very weedy in the fall, instead of mowing it, I can spray it with 1 qt/ac glyphosate with rain in the forecast. That will kill all the grasses and many broadleaf weeds and top kill the clover. I can then drill something like radish and/or Winter Rye into the field. The radish and/or WR will germinate and start growing and then the clover will bounce back from the well established root system. I've posted this pic many times before:
The radish is an annual and will die over the winter. That field will look perfect the next spring with nothing but clover in it. But, it is still a 6 or 7 year old field that has been sucking out the same nutrients each year and fixing N back into the soil making conditions for grasses and other N seeking crops. I'll get another 3 years or so out of the field but it will get grassy much faster than the original field. But this does give me an extra couple years to find the time to rotate.
When it is time to rotate, I'll typically plant buckwheat in the spring and follow it with some fall mix that has a brassica and grain component. I'll go back to the buckwheat the next summer and then plant my clover with the nurse crop of WR the next fall. By then the soil is ready to support clover again. By tolerating weeds, we are actually encouraging diversity of plants in the soil improving the quality of the clover that is there and some of the weeds will be great deer food.
Gly is much less expensive and I'm only using it once in the life of the plot. I probably would not do this in gly resistant areas and I only use this technique when I don't have time to rotate when needed.
Thanks,
Jack