The cotton plant does not produce more roots in areas with high nutrient content in the same way as cereals, creating a challenge of where it is best to apply P to make the plants absorb it with ease. In general, only 20-30 percent of the applied P-fertilizer is used by the crop in the application year, and the remaining P will be bound up in the soil and may be used for later.
Phosphorus normally exists in two “pools” in the soil. One is the slow release pool where the P is quite immobile and in compounds such as calcium phosphate. The slow release pool will deliver P to the other pool, called the fast release pool and in this way the slow release pool gets depleted over time. The fast release pool delivers P into the soil solution from where the plants supply themselves.
The fertilizer strategy must replace the P taken away by the crop each year. Due to P’s immobility, it is important to apply P fertilizers in a way that a large as possible volume of soil is treated, so broadcasting is preferred to row applications. Incorporation can also be beneficial.
Creating the right nutrient management strategy in Cotton production is not a “one-size-fits-all” prescription. Cotton is grown in vastly different environments with differing soil conditions and yield potentials. Any nutrient program needs to be designed for these variables. But where do you start? Find these answers and more in this free webinar by Cotton Grower.