MECHANICAL VACUUM EXTRACTION VS BATCH EQUILIBRATION FOR ESTIMATION OF EXCHANGEABLE CATIONS

Mechanical vacuum extraction (MVE) was compared with a typical batch extraction involving a shake followed by filtration in a Buchner funnel (SF) for estimation of exchnageable cations in acidic forest soils. The relative efficiency of the MVE procedure vs. the SF procedure generally increased with increasing charge density, following the lyotropic series. The SF procedure yielded high precision for Al estimation; for exchangeable Ca, the precision of estimates was equivalent by the two methods. -from Authors