[Effects of Long-term Fertilization Regimes on As Accumulation in Upland Red Earth and the Crops Growing on It].

To investigate the effects of different long-term fertilization treatments on arsenic (As) accumulation in upland red earth and the crops growing on it, different fertilization treatments, including no fertilization (CK), fertilization with chemical fertilizers containing nitrogen, phosphorus and potassium (NPK), fertilization with swine manure (M), and fertilization with chemical fertilizers plus manure (NPKM), in a long-term fertilization site located in Qiyang County, Hunan Province, were selected.. The results showed that after 26 years of fertilization, both the total and available As concentrations in the soils were significantly improved in the fertilized soils (i.e., NPK, M, and NPKM) when compared to the CK soil. Meanwhile, NPK treatment had the highest As concentration (44.68 mg·kg), which was higher than the national standard value (40 mg·kg) in acidic soils. Fertilization practices had the biggest impacts on the non-specifically-absorbed As, followed by the residual As, and the well-crystallized hydrous oxides of Fe and Al absorbed As, but minor impacts on the amorphous and poorly-crystalline hydrous oxides of Fe and Al-absorbed As, and the specifically absorbed As. Furthermore, NPKM treatment significantly decreased the concentrations of As(Ⅲ) and As(Ⅴ) in the soils, when compared to the other treatments. Also, M treatment could cause the accumulation of As in the grains and straws in corn. In contrast, M treatment could not cause the accumulation of As in the grains and straws in wheat. Furthermore, correlative synchrotron-radiation-based FTIR and micro X-ray fluorescence spectromicroscopic analysis showed that As had a similar distribution pattern with clay -OH and C-OH.