We talk a lot about soil fertility on HyMark High Spots. This piece from Ernie Flint in Mississippi, describes what I've learned.
"For years I have been looking for a common denominator that would offer a clue as to why some of the corn does not produce more than about 120 bushels per acre even in a good year while only a few miles away growers on similar soils produce 150 or more. On occasion these higher yields reach 180 or more during the exceptional year with good rainfall.
The only idea I have been able to pull from this situation is that producers with higher yields stay ahead of the curve on their liming and fertilization, allowing their corn to have easier access to nutrients. Instead of trying to keep soil pH above 5.5 they maintain it consistently above 6.2. Instead of trying to keep MSU soil test phosphate and potash levels at 50 and 120 pounds per acre, they keep these levels near 110 and 300 or higher. They also make sure that secondary and minor elements like Zinc, Magnesium, and Sulfur are not in short supply.
Those who have access to poultry litter go beyond these levels, their challenge being how to keep potash up to ratio with phosphate. And another “secret” to this is that higher yields usually come from fields where growers have been staying ahead of their soil fertility needs for several years. The change does not seem to occur in one year, but is the result of long term soil building. In these well-fed soils nutrients move deep into the profile to feed roots wherever they go.
I became convinced this might be the answer to my question when I noticed that one of the most productive cotton producers in the area made 160 bushels on corn that was planted for rotation. These fields were in the middle of an area where corn yields usually top out around 100. His aggressive fertility program looked like the key to the lock, and it agreed with what I had seen in other areas."
When it comes to soil fertility, I've become a lot more offensive and am in a position where I can afford to be. That's the best defense I have for a good crop.