<i>Effects of phosphorus fertigation and lateral depths on distribution of Olsen-P in soil and yield of maize under subsurface drip irrigation</i>

Drip fertigation has proved to be an effective approach to improve the fertilizer use efficiency in intensively managed agriculture. However, the phosphorus fertigation was rarely applied because of the poor water solubility of the majority types of phosphate fertilizers. Pot experiments of maize (Zea mays L.) under drip irrigation were conducted in 2016 to evaluate the effects of phosphorus fertigation and lateral depths on distribution of Olsen-P in soil and growth and yield of maize. Three lateral depths at 0, 15, and 30 cm beneath the soil surface and two phosphate fertilizer application methods (single basal application and fertigation) were tested. Phosphate fertilizer was blended into the 0-15 cm soil before the sowing at a rate of 100 kg ha-1 of P205 for the control treatments while the equal amount of phosphate fertilizer was fertigated at three splits of 40%, 40%, and 20% in the seeding, jointing, and filling stages, respectively. The distribution of Olsen-P in soil, plant height, leaf area index (LAI), and yield were measured regularly during the maize growing season. The results demonstrated a higher content of Olsen-P near drip emitters for the fertigation treatments while the Olsen-P were mainly distributed in the 0-15 cm soil for the control treatments. The phosphorus fertigation could improve the efficiency of phosphate fertilizer while the area-weighted average content of Olsen-P following the second fertigation event averaged over the three lateral depths decreased from 8.1 mg kg-1 for the fertigation treatments to 5.1 mg kg-1 for the control treatments. The ANOVA results indicated that both the phosphate fertilizer application methods and the lateral depths imposed significant effects on plant growth and yield of maize at a significance level of p < 0.05.The phosphorus fertigation significantly improved the growth and yield of maize. The yield averaged over the three lateral depths for the fertigation treatments were 13% higher than that for the control treatments. The average yield of maize for the treatments with lateral depth of 15 cm was 6% higher than the treatments with lateral depth of 0 cm, while the treatments with lateral depth of 30 cm had significantly lower average yield. The phosphorus fertigation and subsurface drip irrigation are recommended to improve the use efficiency of phosphate fertilizer.