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| There are two schools on variable rate.
One is to pull back where the marginal return is poor, like backing off on the poor ground and apply more on the good ground where there's a greater response.
The other is to feed the good ground enough for a decent yield, probably the most economical yield for the applied nutrients, and the feed the poor ground more to try to make it catch up. To achieve a decent yield without breaking the bank applying fertilizer.
I'd think it would be best to apply fertilizer on each soil to the point were adding more didn't give much response, the economical limit for fertilization. As a practical matter these days, we spend more on seed and land rent or ownership than on fertilizer and if we over apply it may stick around for future years where weather may make a super crop grabbing more than we applied. Especially for P and K and to some extent with N stored in organic matter.
I've had a tendency to be stingy with N, and my best crop was in 2007 with 173.2 bushels on 111 units of applied N. Having 11 or 12% organic matter may have helped a lot, choosing a hybrid that didn't demand a lot of N surely helped, and splitting the application helped a great deal. My tenant in the last four years strip tilling corn on corn with bocoup fertilization has only beat that yield once. He splits the N application too.
Gerald J. | |
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making 200bpa ground out of 150bpa ground....
