Impacts of long-term inorganic and organic fertilization on phosphorus adsorption and desorption characteristics in red paddies in southern China

Abstract

Soil phosphorus (P) adsorption and desorption occur in an important endogenous cycle linked with soil fertility problems and relevant to the environmental risk assessment of P. In our study, the effect of long-term inorganic and organic fertilization on P adsorption and desorption characteristics in relation to changes in soil properties was evaluated by selecting three long-term experimental sites in southern China. The selected treatments at each site were CK (unfertilized), NPK (synthetic nitrogen, phosphorus and potassium) and NPKM (synthetic NPK plus manure). The adsorption and desorption characteristics of P were evaluated using Langmuir and Freundlich isotherms. The results showed that long-term application of NPK plus manure significantly increased soil organic carbon (SOC), total P and available P at all three sites compared with the NPK and CK treatments. All three treatments fit these equations well. The maximum adsorption capacity (Qm) of P increased with NPKM treatment, and the binding energy of P (K) and the maximum buffering capacity (MBC) showed increasing trends. NPKM showed the highest Qm (2346.13 mg kg-1) at the Jinxian site, followed by Nanchang (221.16 mg kg-1) and Ningxiang (2219.36 mg kg-1). Compared to CK and NPK, the NPKM treatment showed a higher MBC as 66.64, 46.93 and 44.39 L kg-1 at all three sites. The maximum desorption capacity (Dm) of P in soil was highest with the NPKM treatment (157.58, 166.76, 143.13 mg kg-1), showing a better ability to release P in soil. The correlation matrix showed a significant positive correlation of SOC, total and available P with Qm, Dm and MBC. In conclusion, it is suggested that manure addition is crucial to improve P utilization in red paddy soils within the recommended range to avoid the risk of environmental pollution.

New insights into sorption and desorption of organic phosphorus on goethite, gibbsite, kaolinite and montmorillonite

“…However, the results obtained agree with the work of Berg and Joern, (2006), which showed a trend of increasing rather than decreasing sorption levels with increasing molecular mass of different forms of OP (IHP > G6P > ATP > IP). Similarly, recent work by Ganta et al, (2020) and Ahmed et al, (2021) also supported our results. They demonstrated that the organic fraction of the OP may not influence the interaction of individual phosphate groups with the soil and thus the effect of molecular mass steric hindrance may be insignificant.…”

“…were also used to determine the best-fitting isotherm to the experimental data. The conceptual framework was performed using correlate and network plot function in the latest development version of the corr package (Ahmed et al, 2021). This generates a network graph of a correlation data frame in which variables that are more highly correlated appear closer together and are connected by stronger paths.…”

Phosphorus status and adsorption characteristics of perennial vegetable-cultivated soils in South China

“…Q m is considered an indicator of the capacity of soil to interact with phosphate, which to a certain extent governs soil P availability [ 18 ]. In this regard, previous studies have reported that long-term fertilization can modify the P adsorption capacity of soil [ 61 – 63 ]. In the present study, it was found that the fertilization of soil over the past four decades has had the effect of reducing the P adsorption capacity of soils in the research area, and we accordingly speculate that continuous application of fertilizers has contributed to a reduction in available exchange sites on the soil surface layer.…”

Coupling phosphate-solubilizing bacteria (PSB) with inorganic phosphorus fertilizer improves mungbean (Vigna radiata) phosphorus acquisition, nitrogen fixation, and yield in alkaline-calcareous soil

“…However, the problem with artificial fertilization is that only 25-30 % of the P applied is available to crops, while the remainder is converted into insoluble P fractions (Penn and Camberato, 2019). Therefore different management strategies, including the use of efficient targeted P fertilizers, organic amendments, plants with low critical P-requirements, and modified farming systems, have been devised to increase P use efficiency in soil systems (Du et al, 2022;Qaswar et al, 2021;Ahmed et al, 2021;Simpson et al, 2011). However, there are limitations on how well these management strategies can improve P use efficiency.…”