Soil phosphorus loss increases under drought-flood abrupt alternation in summer maize planting area

Phosphorus (P), critical nutrient for plant growth and environment, has been greatly concerned. Abundant studies have been focused on soil P loss, while only sparse studies have concerned on soil P loss under extreme hydrological events, even less on drought-flood abrupt alternation (DFAA). This study explored the P migration in summer maize farmland systems based on field experiments, further obtained the proportion of soil P loss. We also simulated the soil P loss to DFAA in summer maize planting area in the Northern Anhui Plain based on history, future, and hypothetical natural (assuming no DFAA events) scenarios. The field experiments revealed that DFAA events reduced plant P storage by 47.7% than that in the natural control systems (CS). The mean proportion of soil P loss increased in the DFAA treatments (8.96%) than that in the CS treatments (1.60%). The numerical simulation results show that the proportion of average annual soil P loss due to DFAA has been increasing in the Northern Anhui Plain, with 7.98–10.34% during 1964–2017, 2.07–14.16% during 2020–2050. The spatial distribution of annual soil P loss changed as well. The soil P loss in hypothetical natural scenario was 5.1 times and 5.9 times lower than that in history and future scenarios, which indicates significantly negative impacts of DFAA on environment. This study can provide references for estimating the environmental effects of DFAA on P in farmland systems.