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| There is much to learn about efficient N usage. Timeliness appears to be everything, corn needs some when sprouting to encourage growth, and then needs N continuously through some much later stage probably before black layer, but some numbers sacrifice the stalk to get the last bits of N for the seed maturation. Traditionally N was put down in the fall in enough quantity to have N to that last need. Much fall applied N left the farm, but that depends a lot on weather. For N efficiency, I sure that some N needs to go down about planting time, not much earlier and sidedressing at least once is important. I have a gut feeling that small appliications at short intervals will get more corn per unit of N than just one sidedressing, but without fertigation the application cost will negate the gains in N efficiency. For sure those small applications will loose less when rain leaches the N. Trouble is with surface application equipment (sprayer or tractor and sidedresser) this year and last it was not possible to get in the field for months at a time, to be timely with many small applications. It was difficult to get in for weed spray and one sidedress pass. And these same rainy conditions are the ones that leached more N from the crop.
I also believe that the breeding of the corn for efficient use of N is important. And the seed companies are so far not admitting they know much, though at the last Amana FPS, many seed representatives promised me N efficient numbers in 2012. That must have been 2006 because I planted a Crows number rated by them to be efficient in use of N and did 173.2 bu on 111 units of N in 2007. I interpret a seed catalog that says, "responds to nitrogen" as meaning really it demands lots of nitrogen and won't produce without excess nitrogen. We almost need a membrane in the soil to hold back N from leaching, I don't know how that might work without holding water to drown the crop. Can we move grain production to hydroponic green houses and make money. I think not.
Gerald J. | |
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Corn and Nitrogen useage
