0000000000447564
AUTHOR
Elisabetta Barberis
Are agricultural soils under a continental temperate climate susceptible to episodic reducing conditions and increased leaching of phosphorus?
International audience; Soil science research has probably underestimated the significance that short-term, episodic cycles of reduction and oxidation has had on phosphorus (P) reactivity. Here, the effects of eleven pulsed reduction-oxidation (including wet-dry) cycles on soil P dynamics are compared for 12 soils having contrasting properties and all overfertilised with respect to P. The laboratory based incubation conditions attempted to simulate transient waterlogging of the soil profile and involved repeated sampling and analysis of both the solution and solid phase P forms. An initial increase in P concentration in solution that occurred up to and including the fourth full cycle was fo…
Release of phosphorus under reducing and simulated open drainage conditions from overfertilised soils
Does removal of cations from soil solution during soil reduction stimulate phosphorus (P) release? An ion-exchange resin system was employed to provide a sink during the incubation of twelve soils under fully reducing conditions. This experimental design was considered to better simulate the loss of ions likely to occur under field conditions than more routine batch type closed extraction systems where solutes build-up in the extract solution. The small solute concentrations that remain in the equilibrating solution suggest the mixed resin system acted as an effective sink over the whole experimental period. By maintaining a small P concentration the resin system mimics soil drainage condit…
Phosphorus Loss in Overfertilized Soils: The Selective P Partitioning and Redistribution Between Particle Size Separates
Using 12 well-characterised European soils contrasting in their physical and chemical properties, we demonstrate significant differences in the partitioning of phosphorus (P) between various particle size separates. Samples of each soil were subjected to one of three methods of increasingly aggressive dispersion in the order water (WD), mechanical (MD) or chemical (CD). A general, although not exclusive, inverse relationship existed between the concentration of various attributes (these included organic carbon, oxalate and dithionite iron contents, total P, resin and water extractable P) and particle size. The quantity, composition and physico-chemical properties of individual size separate…
The influence of pulsed redox conditions on soil phosphorus
Abstract. The effects of eleven pulsed reduction-oxidation cycles (20 and 2 days, respectively) on soil phosphorus (P) dynamics are compared for 12 soils having contrasting properties and overfertilised with respect to P. Incubation conditions simulated transient waterlogging of the soil profile and involved repeated sampling and analysis of both the solution and solid phase P forms. An initial increase in P concentration occurred upto and including the fourth full cycle was followed by a sharp decline in concentration for all but one soil. Accompanying changes in the main extractable forms of P, which appeared to be cumulative, could be summarised as a general decline in the organic P frac…