Supplying the Right Nutrients at
the Right Time to Cotton Fields
In this article, I would like to discuss some observations to cotton fields that I have made that often times determines whether a cotton crop produces the highest economical yield possible or a disappointing yield that puts the farmer in a financial stress. Many of you that I have worked with over the past 35 years, and know me well, have heard me say many times that “Proper timing of all crop inputs are as critical as the decision to do something”. Providing the inputs that the crop needs and doing it at the right time continues to be the determining factor between success and failure.
The cotton varieties that have been developed over the past 10 years have the potential to produce extremely high yields if they are managed properly. A balanced fertility program is critical in the production of the highest economic yields that these much improved cotton varieties are capable of attaining.
There are two nutrients that I want to focus on here that I have seen limiting the yield potential of many of our cotton fields.
The first is potassium, widespread potassium deficiency problems occur in cotton throughout the Southeast every year. A potassium deficiency predisposes our cotton to leafspot diseases such as Stemphylium, Cercospora, and Alternaria leaf spot. These leafspot diseases are considered secondary to a potassium deficiency and if a potassium deficiency is avoided these leafspot diseases are not normally a problem. If your goal is to produce the highest economical yields, you must follow a good soil applied fertility program with a good foliar program, with emphasis on suppling foliar potassium to the cotton plant. The correct timing for these foliar application are from the first week of bloom through the 5th week of the bloom period. UGA research as well as my on farm large block trials indicate that foliar K is more effective than sidedress K in improving yields in cotton. These foliar potassium application are critical on our deep sandy soils. We have several foliar formulations containing potassium that we make here at Big Bend to fit the needs of your crop. I would be happy to discuss these with you. Please email me at: AgronomyTips@BigBendInc.com
The second nutrient that I feel is limiting yield and quality in Boron. Not because we are not putting enough on most cotton fields, but because Boron is being applied too late in many of our fields.
Boron is an essential micronutrient for our cotton crop that is important for flowering, essential in germination of pollen grains and growth of pollen tubes, seed and cell wall formation, and fruiting of the cotton plant. The standard research based recommendation is a total of 0.5 pounds of Boron, applied in two or three foliar applications between first square and first bloom. I have found that rates above 0.4 pounds of Boron in one application can cause some foliage burn in cotton. Therefore, my recommendation is for 1 quart per acre of one of our 10% Boron product such as Supra-Bor in each application. Two 1 quart applications of one of our 10% Boron Products applied between first square and first bloom will provide 0.55 pounds of Boron per acre to your cotton crop.
Foliar applications above this base recommendation of 0.5 pounds B per acre and up to 2.0 pounds per acre may help move nitrogen and carbohydrates from leaves into developing fruit. Since B leaches readily through sandy soils, foliar applications have always been considered the most effective and efficient application method.
My Boron recommendations for cotton growers that want to do everything they can to produce excellent economical yields and quality are as follows: Apply two to three 1 quart applications of one of our 10% foliar Boron products between first square and first bloom. Then apply 1 quart per acre of one of our 10% Boron products tank mixed with other materials (such as growth regulators, insecticides, etc.) any time you are going over the field between the first week of bloom through the fourth week of bloom, not to exceed 7 quarts of 10% Boron for the entire season.
I have only covered two of the essential nutrients that are necessary to produce a profitable cotton crop. However, in my field observations, I believe Potassium and Boron management are the areas where we are giving up the most yield. If you ever have questions, or concerns you are seeing in the field, give me a call or send me an email. I am available to make field visits with you and your growers.
Sincerely, Don Clark
Consulting Agronomist, CCA# 451971
