Phosphorus Fertilization through Drip Irrigation

Although P fertilization through drip irrigation systems has not been widely recommended, a review of currently available literature indicates this fertilizer application technique can offer many advantages when performed properly. Using drip irrigation to apply P fertilizer allows nutrient placement directly into the plant root zone during critical periods of nutrient demand. Less P fertilizer is generally required to achieve sufficient tissue P concentrations and equivalent yields when it is drip‐applied than with other application methods. The distribution of drip‐applied P in soil depends on soil properties, the source of P fertilizer, the rate of application, and the amount of applied water. When irrigation water contains elevated concentrations of Ca2+ or Mg2+, acidic P fertilizers are effective in drip systems for preventing precipitation of insoluble P salts. A variety of other soluble P fertilizers have been successfully used where the dissolved salt concentration of the irrigation water is low. A fertilizer compatibility test with the irrigation water should be conducted before injecting any soluble P fertilizer into a drip irrigation system.