Are additional plant nutrients needed?
The decision to apply post-plant fertilizers is in some ways the most difficult aspect of chemigation. The decision is always somewhat subjective, and it can be difficult to collect data to aid in making the decision. With cotton and corn, nitrogen is the nutrient most likely needed in a post-plant application. Preplant application of phosphorus and potassium is almost always adequate for a complete growing season. A decision to apply nitrogen after planting may be based on a history of yield responses with post-plant nitrogen applications by more conventional methods, the appearance of deficiency symptoms, or the results of tissue testing for nitrogen. Tissue testing for nitrogen has had poor acceptance in Mississippi because water stress interferes with the test results. Properly irrigated crops should be less subject to this complication. • Is selected material suitable for application with an irrigation system? The simplest fertilizer materials for water injection are true solution
