Phosphorus adsorption, availability, and potential loss characteristics in an Ultisol‐derived paddy soil chronosequence, using a stirred‐flow chamber study

Abstract

The 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 (Fe d and Al d , respectively), suggesting that the major P sorbents were Fe d and Al d . 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.Abbreviations: Ald, free Al (hydro)oxides; C e , the P concentration in the equilibrium solution at low P input; CK, control; DCB, the sodium dithionite-citrate-bicarbonate; DPS, the degree of P saturation; EPC0, the equilibrium solution P concentration; Fed, free Fe (hydro)oxides; k d , the slope of the linear relationship; P 0 , the concentration of the original adsorbed P; P ad , calculated P adsorption; PS0, reference upland Ultisol; PS22, paddy soils after 22 years of rice cultivation; PS7, paddy soils after 7 years of rice cultivation; PS80, paddy soils after 80 years of rice cultivation; PSD, particle size distribution; Q m ad , P adsorption capacities; Q m des , P desorption capacities; SFC, stirred-flow chamber; SOM, soil organic matter; YRSES-CAS, the Yingtan Red Soil Ecological Station, the Chinese Academy of Sciences.

Cadmium in Paddy Soil and Rice Crop in Indonesian Intensive Farming System

“…Based on the results of laboratory analysis in Table 1, soil P-available ranged from 0.31 -4.84 mg kg −1 with an average of 1.87 mg kg −1 ± 1.75 which was classified as very low. Meanwhile, low P in paddy soil cultivated in the long term was due to P adsorption phenomena in paddy soil (Hua et al, 2023). Soil pH was closely related to the availability of P in soil.…”