Affiliation:
1. State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing China
2. University of Chinese Academy of Sciences Beijing China
Abstract
AbstractThe adsorption characteristics, availability, and a loss risk of phosphorus (P) in paddy soil chronosequences had not been well established. In the present study, P adsorption characteristics of paddy soil chronosequence with 0, 7, 22, or 80 years of paddy cultivation history (PS0, PS7, PS22, and PS80, respectively) were identified by P adsorption isotherm, envelope, and stirred‐flow chamber (SFC) kinetics, along with the assessment of P availability and loss risks. Results indicated that P adsorption and desorption followed the same order of PS0 > PS7 > PS22 > PS80. Pearson's correlation analysis revealed P adsorption capacity was significantly and positively correlated with the concentrations of both free iron (Fe) and aluminum (Al) (hydro)oxides (Fed and Ald, respectively), suggesting that the major P sorbents were Fed and Ald. Findings from SFC adsorption kinetics suggested that the kinetics of both P adsorption and desorption were biphasic, being fast in the first 100 min (75.11%–87.57% of P adsorbed and 79.00%–88.65% of P released), followed by a slow phase for the remaining 180 min. Bray‐P increased with the duration of rice cultivation and reached a maximum of 77.90 mg kg−1 at PS80, along with the highest P saturation degree and equilibrium phosphorus concentrations of 7.56% and 2.33 mg L−1, respectively. Hence, with an increasing duration of paddy cultivation, there was a less pronounced P sink function and a lower P availability, but a higher P loss risk, indicating that P availability in the younger and loss risk in the older Ultisol‐derived paddy soils deserve greater attention.
Funder
National Natural Science Foundation of China
National Key Research and Development Program of China