Phosphorus loss and migration characteristics in paddy fields under different fertilization treatments

Phosphorus is a restricted element as it causes eutrophication of especially still water systems. Due to the excessive application of phosphate fertilizers in recent years, farmlands have become the major source of phosphorus which causes water eutrophication. To determine optimal phosphorus applications in paddy fields, a field lysimeter experiment was conducted under different treatments of organic fertilizer (OT), mixed fertilizer (MT) and chemical fertilizer (CT). Phosphorus loss and migration characteristics in the fields under different treatments, and treatments effects on yield and phosphorus utilization ratio of paddy rice were analyzed. Results showed that runoff loads of phosphorus under CT, MT, and OT were 0.56 kg(P)·hm^-2, 1.13 kg(P)·hm^-2 and 4.19 kg(P)·hm^-2, respectively. Also leaching loads of phosphorus under CT, MT and OT were 0.42 kg(P)·hm^-2, 0.44 kg(P)·hm^-2 and 0.45 kg(P)·hm^-2, respectively. Phosphorus loss in paddy fields was mainly through runoff, accounting for 56.86%?90.38% of total phosphorus loss. Runoff of phosphorus was mainly driven by fertilizer dose and rainfall intensity, and the loss through the first runoff accounted for about 50% of phosphorus loss. Phosphorus leach was not influenced by phosphorus dose, and over 80% of phosphorus loss occurred in the first 30 days after fertilizer application. Soluble phosphorus was the main form of phosphorus in surface water, seepage water and runoff water. While it was possible for MT and OT to ensure sufficient phosphorus supply in soils, CT decreased Olsen-P and organic matter in soils. Yields of paddy rice under the three treatments were significantly higher than that under the control, among which MT had the highest yield (6 728.84 kg·hm^-2). Phosphorus fertilizer use efficiencies under CT and MT were significantly higher than that under OT. In conclusion, MT was better fertilzation pattern for phosphorus loss control, soil nutrient utilization and paddy rice yield in eco-agricultural systems in China.