Lime quality

Particle size

While the quality of agricultural lime deposits can vary widely, high-quality lime is available from limesand, limestone and dolomitic lime sources.

The size of the lime particles determines how quickly the lime can neutralise acid. Lime with a higher proportion of finer particles has a larger surface area to react with the acid in soil. Research shows that finer limes (a high proportion of particles less than 0.5mm) increase pH faster, which is necessary for rapid amelioration of acidic soil (Figure 3).

Figure 3 Finer particles of agricultural lime were more efficient in changing soil pH at an application rate of 2.5t/ha (from Cregan et al., 1989)

Suppliers of limestone and dolomitic lime crush and screen their products and suppliers of limesand may screen to remove vegetation if necessary. This processing ensures supply of a consistent product. Suppliers should provide details of the particle size distribution of their product. Farmers should ensure that products contain an adequate proportion of fine particles to meet their needs (Figure 4).

Figure 4 Coarse and fine limes with the same neutralising value treat the same amount of acidity, but the finer lime does it quicker