Field Guide. cropping and pastoral grazing on flat to rolling country.

SOIL INDICATORSSoil porosity under pasture Remove a spade slice of soil from the side of the hole created bytaking the 20 cm cube of topsoil, or take a number of clods from theaggregate distribution test. Examine for soil porosity, comparing with the three photographsopposite.SOIL POROSITY, <strong>and</strong> particularly macroporosity (the number of largepores), controls the movement of air <strong>and</strong> water in the soil. It is importantto assess soil porosity as well as aggregate-size distribution. Soils withgood structure have a high porosity between <strong>and</strong> within aggregates,but soils with large structural units may not have macropores <strong>and</strong> coarsemicropores within the large clods, <strong>and</strong> may not be adequately aerated.Restricted air <strong>and</strong> water movement reduces root activity <strong>and</strong> pasturegrowth.58 VISUAL SOIL ASSESSMENT: Volume 1