Kinetics of inorganic and organic P release from red clover (Trifolium pratense L.) and ryegrass (Lolium multiflorum L.) upon frost or drying

Abstract

An incubation study with fresh, frozen, and dried clover and rye-grass shoots gathered in autumn was performed in the laboratory (43 days). The aim was to study inorganic and organic phosphorus (P) release from plant material during decomposition without soil. Plant materials (2 cm size) were mixed with small glass beads and placed in large syringes for consecutive water extractions on 7 occasions. Leachates were analysed for inorganic and total P. At the first leaching event, 8% of total crop P was released from fresh, 24% from frozen and 27% from dried plant material. During decomposition, both inorganic and organic P was released following first order kinetics, with grass releasing mostly inorganic P and clover mostly organic P. After 43 days, 42%-50% of total crop P from fresh, 49%-51% from frozen and 57%-69% from dried material was released, with significant differences between treatments. Using the results in calculations on field scale showed that P released from overwintering crops under cold climate conditions can amount to several kg P ha(-1). Thus, senescence of overwintering aboveground biomass can be a significant source for P leaching from soils.

Keywords

Freezing-thawing; drying; overwintering crops; water-soluble P; organic P; P dynamic; P leaching

Published in

Acta Agriculturae Scandinavica, Section B - Soil and Plant Science
2017, volume: 67, number: 8, pages: 693-696

SLU Authors

• Kirchmann, Holger

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Soil Science

Publication identifier

• DOI: https://doi.org/10.1080/09064710.2017.1339823

Permanent link to this page (URI)

https://res.slu.se/id/publ/85551