Effect of different phosphatic fertilisers applied at sowing on the survival of inoculated Rhizobium trifolii and on the nodulation of clover

Abstract

Dical-super, a new phosphatic fertiliser, had little or no effect on the survival of rhizobia when the fertiliser was mixed with inoculated seed of subterranean clover. Superphosphate reduced rhizobial survival when the inoculated seed was not protected by a seed coating of lime. When dical-super was sown in rows with inoculated clover seed into very acid soil (pH 4.6, 1:5, soil:water) additional lime (in the form of a lime coating on the seed) was needed to ensure good nodulation of the clover. When sown in a less acid soil (pH 5.3) no lime was needed. When superphosphate was the fertiliser applied at sowing, additional lime, as fertiliser and/or lime pelleting of the seed, was needed to obtain a high number of nodulated plants in the very acid soil. Lime pelleting only was needed in a less acid soil to obtain good crown nodulation.