The use of biologically based phosphorus fractions to evaluate soil P availability in reduced P‐input paddy soils

Abstract

Chemical soil phosphorus (P) extraction has been widely used to characterize and understand changes in soil P fractions; however, it does not adequately capture rhizosphere processes. In this study, we used the biologically based phosphorus (BBP) grading method to evaluate the availability and influencing factors of soil P under four P fertilizer regimes in a typical rice–wheat cropping rotation paddy field. Soil P was assessed after seven rice‐growth seasons at multiple growth stages: the seedling, the booting and the harvest stage. Soil CaCl2‐P, citrate‐P and HCl‐P (inorganic P, Pi) as well as enzyme‐P (organic P, Po) were not significantly different between soil treated with P fertilizer during the wheat season only (PW) and during the rice season only (PR) compared with soil treated during both the rice and the wheat seasons (PR+W) at all three rice‐growth stages. No P fertilizer application during either season (Pzero) significantly reduced the concentration of soil citrate‐P and HCl‐P at the rice‐seedling and harvest stages. Significant correlations were observed between the HCl extraction and Olsen‐P (R2 = 0.823, P < 0.001), followed by enzyme‐P (R2 = 0.712, P < 0.001), citrate‐P (R2 = 0.591, P < 0.001) and CaCl2‐P (R2 = 0.133, P < 0.05). Further redundancy analysis (RDA) suggested that soil alkaline phosphatase (S‐ALP) activity played a role in soil P speciation changes and was significantly correlated with enzyme‐P, citrate‐P and HCl‐P. These results may improve our ability to characterize and understand changes in soil P status while minimizing the overapplication of P fertilizer.

Organic Fertilization Improves the Availability and Adsorptive Capacity of Phosphorus in Saline-Alkaline Soils

“…However, little is known about the effects of organic fertilizer on soil P fractions and adsorptiondesorption characteristics involving the improvement of soil P availability. P fractions are considered as a crucial index to assess the P availability (Yuan et al 2018) and often are designated as either inorganic or organic (Hedley et al 1982). It could increase the availability of soil P through non-labile P to labile P fractions with organic fertilizer application (Fei et al 2019).…”

Effects of maize/soybean intercropping on rhizosphere soil phosphorus availability and microbial phosphorus cycling genes in Northwest China

“…4). Citrate-P is an active inorganic P extracted by citric acid solution, which characterizes the process of soil microbes and plant roots acidifying the soil environments by secreting organic acids and protons (DeLuca et al 2015; Yuan et al 2018;Wang et al 2023). In the present study, the citrate-P content of maize monoculture systems was higher than that of the other treatments we studied, which may due to the different crop root types.…”