Assessing phosphorus availability in paddy soils: the importance of integrating soil tests and plant responses

Abstract

Phosphorus (P) cycling in paddy soil is closely related to iron (Fe) redox wheel; its availability to rice has thus generally been ascribed to Fe minerals reductive dissolution. However, the literature aimed to identify the best method for predicting rice available P does not uniformly point to Fe reductants. Rice plants can indeed solubilize and absorb P through many strategies as a function of P supply, modifying the chemical environment. Therefore, this study aims to estimate P availability in paddy soils coupling the redox mechanisms driving P cycling with concurrent plant responses. Soil available P was estimated in three groups of paddy soils with low, medium, or high P content assessing easily desorbable pools (0.01 M calcium chloride, Olsen, Mehlich-III, anion exchanging resins) and Fe-bound P pools (EDTA, citrate-ascorbate, and oxalate). Rice P uptake and responses to P availability were assessed by a mesocosm cultivation trial. Although P released in porewater positively correlated with dissolved Fe(II), it did not with plant P uptake, and readily desorbable P pools were better availability predictors than Fe-bound pools, mainly because of the asynchrony observed between Fe reduction and plant P demand. Moreover, in low P soils, plants showed higher Fe(II) oxidation, enhanced root growth, and up-regulation of P root transporter encoding genes, plant responses being related with changes in P pools. These results indicate the generally assumed direct link between Fe reduction and rice P nutrition in paddy soils as an oversimplification, with rice P nutrition appearing as the result of a complex trade-off between soil redox dynamics, P content, and plant responses.

Drainage Practice of Rice Paddies as a Sustainable Agronomic Management for Mitigating the Emission of Two Carbon-Based Greenhouse Gases (CO2 and CH4): Field Pilot Study in South Korea

“…In general, the differences in crop production can be attributed to P availability in soils [4,34]. In this study, the concentration of available P determined for CF paddies was higher than ID paddies, primarily due to the enhanced reductive dissolution of P-bearing minerals in flooded paddies [4,34]. However, the level of P in these paddies satisfies the required level (e.g., 13.5 mg kg −1 ) for rice paddies recommend by Korean RDA.…”

“…Similarly, Liu et al [7] showed with meta-analysis data that the intermittent drainage has no effect on rice yield as long as the SOC level and N content (e.g., 50 kg N ha −1 ) are sufficiently high, due to the enhanced decomposition of SOC in drained paddy. In general, the differences in crop production can be attributed to P availability in soils [4,34]. In this study, the concentration of available P determined for CF paddies was higher than ID paddies, primarily due to the enhanced reductive dissolution of P-bearing minerals in flooded paddies [4,34].…”

Respon Pertumbuhan dan Produksi Padi (Oryza sativa L.) Pada Kombinasi Pupuk Organik Granular dan Anorganik

“…Unsur P dapat memacu peningkatan efisiensi kerja kloroplas dalam daun yang berperan dalam suplai dan transfer energi pada seluruh proses biokimia (Booromand & Grough, 2012). Selain itu unsur P juga berperan dalam mendukung pertumbuhan padi mulai dari awal pertumbuhan vegetatif sampai fase pembentukan bunga dan pematangan biji (Ye et al, 2019;Martinengo et al, 2023).…”

The influence of phosphorus availability on rice root traits driving iron plaque formation and dissolution, and implications for phosphorus uptake

“…The availability of P in paddy soils is strongly driven by redox conditions, although the higher soil solution P concentrations under reducing conditions do not necessarily result in a higher plant P uptake (Martinengo et al 2023). Previously, low P uptake by rice has been attributed to high P sorption capacity of newly formed Fe minerals near the root surface (Zhang et al 2003;Kirk 2004;Veelen et al 2020).…”