Coupling effects of phosphate fertilizer type and drip fertigation strategy on soil nutrient distribution, maize yield and nutrient uptake

Fertigation strategy has been shown to impact nitrogen distribution in drip irrigation, but it remains unclear whether it would impose a comparable effect on phosphorus migration in phosphorus fertigation. A two-year field experiment was conducted to evaluate the effects of different phosphorus sources (mono-ammonium phosphate (MAP) and ammonium polyphosphate (APP)) and four fertigation strategies with varying sequences and durations of water irrigation and fertilization in the irrigation cycle (i.e., applying the fertilizer for the full irrigation cycle, 1/4 W-1/2 F-1/4 W (first applying water (W) for one-fourth of the total irrigation time, then applying fertilizer solution (F) for one-half of the total irrigation time, followed by applying water (W) for the remaining irrigation time, 1/2 W-1/2 F, and 1/2 F-1/2 W) on soil nutrient distribution, maize yield, and nutrient use efficiency. The results indicated that advancing the fertilization period within an irrigation cycle favored nitrogen and phosphorus migration, especially in the 10-40 cm soil layer. APP enhanced soil phosphorus mobility and availability compared to MAP under a given fertigation strategy, particularly during the maize filling stage. The combined performance of fertigation strategies and phosphorus sources varied in terms of soil nutrient distribution and nutrient uptake. MAP is more suitable for fertigation strategies with more post-fertilization irrigation water. For simultaneous fertigation with nitrogen and phosphate fertilizers, it is recommended to apply nitrogen and weakly adsorbed phosphate fertilizers during the middle of the irrigation cycle, while strongly adsorbed phosphate fertilizers occur earlier, along with appropriately extending the duration of post-fertilization water application.