Soil As supply amount under long-term application of pig manure and its relationship with As uptake of rice

To clear the changes of soil As（ Arsenic） forms after long-term application of pig manure and its migration mechanism in soil-plant system，four treatments including fertilizer（ CK），NPK fertilizer（ NPK），NPK fertilizer with pig manure in early rice（ NPKM1） and NPK fertilizer with pig manure in late rice（ NPKM2） were set based on one long-term fertilization experiment（ since 1981），then，soil As forms and As uptake of grain and straw were analyzed. The results showed that: compared with CK，the soil total As content in NPKM1 and NPKM2 increased by 148.71% and 282.11% respectively，their soil As pools increased by 120.35% and 120.35% respectively. Compared with NPK treatment，the soil total As content in NPKM1 and NPKM2 increased by 90.48% and 192.64% respectively，their soil As pools increased by 83.28% and 83.28% respectively. Meanwhile，soil As forms in NPKM1 and NPKM2 increased significantly than CK and NPK. The proportion of Fe - As was the highest among all soil forms，followed by Al-As and Res-As，but Ca-As and and Ex-As were smallest. Compared with NPKM1，the contents and pools of Ex-As，Al-As，Fe-As，Ca-As and Res-As in NPKM2 significantly increased. At the same time，NPKM1 and NPKM2 could significantly increase the As uptake of straw and grain than other treatments. It was found that the soil Ex-As had the highest contribution to rice As uptake through fitting equation.