A Holistic Approach to Understanding the Desorption of Phosphorus in Soils.

Daniel Menezes-Blackburn,Martin Blackwell,Courtney D Giles,Marc Stutter,Timothy S George,Lawrie Brown,Tegan Darch,Renate Wendler,David Lumsdon,Patricia Cooper,Charles Shand,Catherine Wearing,Philip M Haygarth,Hao Zhang

doi:10.1021/acs.est.5b05395

Abstract

The mobility and resupply of inorganic phosphorus (P) from the solid phase were studied in 32 soils from the UK. The combined use of diffusive gradients in thin films (DGT), diffusive equilibration in thin films (DET) and the "DGT-induced fluxes in sediments" model (DIFS) were adapted to explore the basic principles of solid-to-solution P desorption kinetics in previously unattainable detail. On average across soil types, the response time (Tc) was 3.6 h, the desorption rate constant (k-1) was 0.0046 h(-1), and the desorption rate was 4.71 nmol l(-1) s(-1). While the relative DGT-induced inorganic P flux responses in the first hour is mainly a function of soil water retention and % Corg, at longer times it is a function of the P resupply from the soil solid phase. Desorption rates and resupply from solid phase were fundamentally influenced by P status as reflected by their high correlation with P concentration in FeO strips, Olsen, NaOH-EDTA and water extracts. Soil pH and particle size distribution showed no significant correlation with the evaluated mobility and resupply parameters. The DGT and DET techniques, along with the DIFS model, were considered accurate and practical tools for studying parameters related to soil P desorption kinetics.

Highlights

Modern agriculture is dependent on phosphorus (P) fertilizer applications to maintain their productivity
To ensure optimal plant growth, P fertilizers are applied to agricultural soils in excess of plant requirements to overcome soil P fixation processes and maintain soil solution P at sufficient levels for plant growth.[3]
In this study we explore the use of diffusive gradient in thin films (DGT) and diffusive equilibrium in thin films (DET) as tools to assess intrinsic P mobility properties of different agricultural soils

Summary

Introduction

Modern agriculture is dependent on phosphorus (P) fertilizer applications to maintain their productivity. In this study we explore the use of diffusive gradient in thin films (DGT) and diffusive equilibrium in thin films (DET) as tools to assess intrinsic P mobility properties of different agricultural soils. The similarities of this system to a plant root and its usefulness as “plant proxy” to study bioavailability was reviewed by Degryse et al (2009).[6] Better knowledge of these mobility properties will allow better understanding and management of the administration of appropriate amounts of P for Received: November 2, 2015 Revised: February 22, 2016 Accepted: February 24, 2016 Published: February 25, 2016

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