Methods of rhizobial inoculation and sowing techniques for Trifolium subterraneum L. establishment in a harsh winter environment

Abstract

Placement of Rhizobium trifolii by vertical band spraying of commercial inoculant in suspension with adsorbing clay and fine lime in the soil, above the fertilizer and below the seed of Trifolium subterraneum L., resulted in better seedling nodulation and establishment on low-fertility problem soils over a wide range of soil moisture conditions, when compared with conventional drill-sowing of inoculated, lime-coated seed. Spray inoculation was especially effective in areas where low winter temperature put substantial stress on development of the symbiotic associations. Seed pelleting required favourable soil moisture to permit movement of the bacteria from the pellet to the rhizosphere. The combination of banded spray inoculation with fungicidal seed dusting significantly increased both the numbers and size of nitrogen-fixing nodules on seedlings, and also young plant growth and winter survival. It is concluded that this technique of simultaneous fertilizer application, seed-bed inoculation and sowing of fungicide-dressed seeds greatly increases the options available in commercial practice, particularly in the harsh winter climate of the Southern Tablelands region of New South Wales.