Cotton Farmers Need to Avoid Applying too Much Nitrogen

By Clint Thompson

Too much nitrogen in your cotton crop this season can damage potential yields and lead to pest outbreaks, according to Audrey Gamble, an assistant professor and Extension specialist at Auburn University.

“Cotton, in particular, we have to put out nitrogen to ensure maximize yields, but we can also start to see a yield penalty when we put out too much. The reasons for that is when we put out too much nitrogen, we get excessive vegetative growth and we’re not getting enough growth being put into boll development,” Gamble said. “When we put out too much, we see excessive vegetative growth and that can lead to boll rot and that can lead to problems with insects.”

Nitrogen is one of 16 essential nutrients required by plants. According to the Alabama Extension website on Plant Nutrients, nitrogen is the element that promotes green, leafy growth. As a primary component of proteins, nitrogen is part of every living cell. Therefore, this element is usually more responsible for increasing plant growth than any other nutrient.

“We need a lot to grow and we don’t retain very much in the soil, especially down here in the Wiregrass where we have sandy soils. When rain comes down that nitrogen is going to leech out of the rooting zone and so we need to make sure we maintain that so the plant can develop,” Gamble said. “Nitrogen is important for so many plant processes. We want to make sure we have that nitrogen in supply for the plant.”

If plants don’t receive enough nitrogen, it causes light green or yellowish foliage on the plant. There is also slower, stunted growth and shedding of older leaves in some plants.

However, there is the danger of applying too much nitrogen. Gamble said the optimum range for nitrogen applications is 90 pounds per acre for cotton, give or take 30 pounds in certain areas.

“Getting it in that correct zone for your crop is important,” Gamble said. “If you’re following a legume or if you know you have excessive growth in those areas, you may want to cut that (rate) back just a little bit. If you know you have problems keeping nitrogen in the field; for example, in a very sandy soil or we know we’ll have some rain coming down, you may want to bump that (rate) up a little bit.

“Our most efficient range would be about 90 pounds to the acre on cotton.”