Plant and Soil

, Volume 68, Issue 3, pp 289–308

Effects of liming on phosphate availability in acid soils

A critical review
  • R. J. Haynes
Article

DOI: 10.1007/BF02197935

Cite this article as:
Haynes, R.J. Plant Soil (1982) 68: 289. doi:10.1007/BF02197935

Summary

The critical factors involved in the plant-soil-phosphorus-lime interaction are outlined and discussed. Conflicting reports suggest that the prior liming of highly weathered acid soils can result in an increase, a decrease, or no change in the availability of applied phosphate. Adsorption of phosphate by amphoteric soil surfaces generally decreases slowly as the pH is raised from 4.0 to 7.0. However, in soils initially high in exchangeable Al3+, liming results in the formation of new, highly active, phosphate adsorbing surfaces as the Al3+ ions precipitate as insoluble polymeric hydroxy-Al cation species. Thus, if an acid soil is reacted with lime and then phosphate, without intervening air drying, liming can increase phosphate adsorption. If the same limed soil is air dried before reaction with phosphate (e.g. adsorption isotherm studies), liming decreases phosphate adsorption. Apparently, air drying alters the surface characteristics of recently limed soils, probably by promoting the crystallization of the hydroxy-Al cation polymers as gibbsite.

An important phenomenon, which is often overlooked, is that liming can increase phosphate availability by stimulating mineralization of soil organic phosphorus. However, at high soil pH values, the precipitation of insoluble calcium phosphates can decrease phosphate availability. Since Al toxicity is characterised by the inhibition of the uptake, translocation and utilization of phosphate by plants, liming often increases the utilization of soil phosphate by plants through amelioration of Al toxicity.

When making lime recommendations or interpreting the data collected from lime-phosphate experiments, it is important to consider all the complex interacting soil and plant factors involved.

Key words

Aluminium toxicity Hydroxy-aluminium Lime Phosphate availability Soil acidity 

Copyright information

© Martinus Nijhoff/Dr W. Junk Publishers 1982

Authors and Affiliations

  • R. J. Haynes
    • 1
  1. 1.Department of Soil ScienceLincoln CollegeCanterburyNew Zealand
  2. 2.Research DivisionMinistry of Agriculture and FisheriesLincolnNew Zealand

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