The Influence of Particle Size on the Agronomic Effectiveness of Agricultural Liming Materials

Abstract

Periodic liming to maintain soil pH (the measure of acidity or alkalinity) is essential to achieve and sustain high crop yields on non-calcareous soils. Liming materials must meet certain specifications regarding their ability to neutralize soil acidity if they are to be sold within the EC. At present, the effectiveness of liming materials is assessed by analysis of their chemical reactivity or Neutralizing Value (NV). However, EC legislation is likely soon to require that methods of analysis also take into account the physical properties of liming materials: particle size, mineralogy and hardness are all physical factors that can Influence reactivity. In particular, particle size can have a substantial effect on lime reactivity in the short term. The significance of particle size as a factor in the overall effectiveness with which agricultural liming materials neutralize soil acidity is reappraised below.