A lot of people are seeing nutrient deficiencies in cotton this year, primarily N and K.

There is no doubt all the rain we have had has moved some nutrients and lost some N especially in sandier fields and in low lying areas that have been water logged.

Some producers have not been able to side-dress yet due to the rainy weather. In that case, I would proceed with normal side-dressing rates.

There is no reason to try to replace pre-plant N. I would avoid the temptation to try and push the crop with higher than recommended side-dress rates as the crop is late and we don’t want to make that any worse with excess N.

Many producers have side-dressed and are worried they have lost some or all of the N, K and S.

It is impossible to determine exactly how much we have lost, but I am primarily concerned about N. The best estimate we can provide can be found in the table on page 67 in the Flue Cure Tobacco Production guide (http://www.tobacco.ncsu.edu/files/2013%20Flue-Cured%20Guide.pdf).

Again, we are only concerned about replacing lost side-dressed fertilizer, not the pre-fertilizer. It is easy to look at the crop and over-estimate how much nutrients have been lost, because in many cases the root system is very small as shown in the photo.

Once the root system recovers, the roots will find some of the nutrients that have been leached down to the clay layer in coastal plain soils.

It will be more critical to monitor N and K this year with petiole testing. It is better to do a good job of testing weekly on a few fields than to do a poor job on all fields.

These tests will not mean much until the roots system has recovered. Choose a few fields that will be indicative of other fields based on rainfall levels and depth to clay.

If you applied all your boron pre, I would plan on including boron in  a side-dress application or in foliar applications during bloom. Boron is also very mobile in the soil.

 

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