Effects of phosphate carrier, phosphate placement, and level of lime application on plant growth on two Oxisols in Natal

Abstract

A glass-house study of two Oxisols revealed a marked response by trudan (Sorghum sudanense) to phosphate (P) placement. Plant response to water-soluble forms of phosphate (superphosphate and superphosphate lime mixture) was greater when this phosphate was granulated or when it was banded than when the powered form was broadcast. Granulation or banding did not, however, affect plant responses to rock phosphate or thermophos. This response to granulation of phosphate was strong in the Farningham soil, but weak in the Clovelly soil which has a lower phosphate fixing capacity. Although both the soils studied can fix large proportions of added phosphate, the considerable difference in their ability to fix phosphate explains why, for Oxisols, fertilizer recommendations based only on estimates of available phosphate in the soil could be unsatisfactory.

Keywords: KwaZulu Natal Province|phosphate|carriers|placements|levels|lime|plants|plant growth|sorghum|responses|soils|fertilisers|growth responses|growth|roots|treatments