Virginia Cotton: Nitrogen – How Much Should You Apply at Planting?

Cotton planting. ©Debra L Ferguson Stock Photography

Nitrogen is needed by the cotton plant at higher amounts than any other nutrient. We have been on a trend of increasing the rate of nitrogen, which is either causing our yields to go up, or because our yields are going up. At any rate, it is pretty intuitive that it takes more to make more.

  • Determining the amount of residual nitrogen from rotational crops, organic matter breakdown, and cover crop can also be a huge variable, so for today, I’d like to cover the decision of how much to provide at planting.
  • Perhaps in an over simplistic idea, application of higher rates at planting will increase the growth of the plant earlier in the season, so that can only be a good thing… right? Well, on a lot of our soils that is the idea.
  • The feeling is that we have the tools to slow it down easier than we do getting it to grow. Light land rarely gets too big and getting that growth early prior to any fruit loading up is desirable.
  • However, there is an “other side” to consider. Higher nitrogen rates at planting increase PGR requirement prior to bloom, delay bloom initiation by favoring vegetative growth, and create a better ecosystem for plantbug development, particularly on better soils.
  • All of these factors tend to be more positive during drier vegetative stages and more negative when rainfall is plentiful or when planting late, particularly on soils with high potential for rank plants.
  • To get right down to it, the old recommendation of 20 pounds of N at planting is still about right for fields that have these higher residual levels of nitrogen or for farmers who split sidedress nitrogen applications or just generally like to put the sidedress out earlier.
  • However, if you want more aggressive growth early, and a better chance of delaying the sidedress until closer to bloom, then 30 to 40 pounds of nitrogen at planting will help accomplish this.
  • The plantbug factor seems more of an issue in production regions east of the Blackwater river and on strong soil types.  If you have been fighting plant bugs, particularly prior to bloom, then you may consider using the lower side of the range at planting and getting more nitrogen in your sidedress.

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