Some factors affecting the extraction of soil 'available' phosphate

Abstract

Twenty soils from southern New South Wales were analysed for acid extractable phosphate in 1971, and again in 1977 when it was found that an increase had occurred. These same samples were also analysed using reciprocating shakers with different distances of travel. More phosphate was extracted when a shaker with a greater distance of travel was used and when more soil, but at the same soil : solution ratio, was placed in a large vessel. It is suggested that such variations in technique contribute to inter-laboratory error in soil tests for phosphate.