Flooding means lost N

What does last year’s flooding mean to soil nitrogen levels? Viterra did a bunch of soil sampling in the fall to compare flooded versus non-flooded parts of fields and they’ve summarized the data to come up with some conclusions. On fields where a crop was seeded and some of the crop was subsequently flooded out, you’d expect more nutrients to be available where there was little or no crop growing. However, the soil testing came up with very little difference. The flooding caused nitrogen losses and since the nitrogen wasn’t lower down in the soil profile, it was probably lost due to denitrification in the waterlogged soil. In general, fallow land that was too wet to seed, but not flooded seems to be well charged with nitrogen. However, there is a great variation from one field to the next. Unseeded stubble fields that were not flooded are generally very low in nitrogen. In general, if a field was fertilized and not seeded, but also not really flooded, a large portion of the nitrogen seems to remain. If a field or a part of a field was flooded, a large portion of the N is typically gone. Given all the variability, soil testing will be more valuable than usual.

I’m Kevin Hursh.

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