How to Fertilize Cotton Plants

Test your soil in the fall, several months prior to planting. Knowing certain essential elements are missing from your soil gives you time to get the right combination. It also gives the elements time to absorb and react with the soil.

Determine whether you need to add lime to your soil by noting your soil's pH level. Cotton needs a soil pH between 5.8 and 7.0. If your test results show a pH level below 5.8, mix lime into the soil. For best results, add lime five to six months before planting.

Identify the consistency of your soil to determine how much nitrogen you need to add. Generally, one bale of cotton requires 50 to 60 pounds of nitrogen-based fertilizer in sandy soil. Increase this amount to 60 to 70 pounds for loamy or medium textured soil. Increase the fertilizer to 70 to 80 pounds in soil that includes a high clay content. Decide approximately how many bales of cotton to produce per acre and use the above information to derive your nitrogen formula. For example, if your soil is of medium consistency and you decide to produce two bales of cotton per acre, then use 120 to 140 pounds of nitrogen-based fertilizer per acre to produce your crop successfully.

Add potassium to your soil in the form of muriate of potash. If you plan to plant less than two bales of cotton plants per acre, add the mineral in the amount recommended by your soil test results. If you plan to plant two or more bales per acre, increase the potassium by half and split the application into two parts.

Mix phosphorus into your soil in accordance with your soil test recommendations. Add it in the fall if your soil pH is between 6.0 and 7.0. If the soil pH is at any other level, add the phosphorus closer to the planting date.

Introduce sulfur into your soil if it is sandy or lightweight. Soil tests are not a true indicator of actual sulfur levels as they only test for certain sources of sulfur. Use any form of commercially available sulfur.