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In a previous issue of Minnesota Crop News (MNCN 11), we reported the results of a survey to monitor nitrate-nitrogen in fields that had been fertilized with either 82-0-0 or 46-0-0 in the fall of 2000. Fields were samples on June 8 and June 11. Results of the analysis of soil samples collected at that time lead to the conclusion that heavy rains in early spring had not caused notable loss of fall applied nitrogen.

Then heavy rains came on June 12, 13 and 14. Did these heavy rains cause a substantial loss of nitrogen? In an effort to get an answer to this question, six fields in Faribault, Jackson, and Cottonwood Counties sampled on June 8 and 11 were sampled again on June 26. The same sampling procedure was used. Soil was taken from 0-12 and 12-24 inches.

The results for the two sampling dates are summarized in the following table.

Except for the Jackson 31 site, the second sampling showed equal or higher values of N0₃-N to 2 feet. The Jackson #1 site was apparently manured and the difference between samplings could be due to the variability of N0₃-N in the soil.

We can only speculate on the cause of the higher N0₃-N values in two fields. Nevertheless, the heavy rains of June 12, 13, 14, caused no loss of N0₃-N in the fields that were sampled. There is no reason to believe that these fields are not representative of many fields that were subject to the heavy rains.