Influence of Fine Particle Materials on Survival of Rhizobium trifolii in Sandy Soil

Abstract

IN a field experiment being carried out by one of us (F. J. R.) and concerned with subterranean clover (Tri-folium subterraneum L.) germination and establishment on very coarse-textured, infertile sands, we observed quite striking nodulation differences between treatments in the year following establishment. The experimental site was on a highly leached, deep, grey sand (Gavin series1) on the Swan Coastal Plain near Perth, Western Australia. Three fine-particle materials were used as soil amendments: (1) finely ground silica; (2) a montmorillonitic clay (Wellesley series1); (3) fly ash—a waste product from a power house consisting mainly of burnt clay. These were screened to pass a 30 mesh sieve and incorporated into plots (7 links × 11 links) to a depth of 3–4 in. and at a rate of 30,000 Ib./acre (= approximately 2.5 per cent of the soil mass to a depth of 3 in.). All plots, including unamended controls, received a complete fertilizer dressing. Lime-pelleted Dwalganup subterranean clover seed was inoculated with a commercial peat culture and sown in autumn 1961. In the first season, nodulation was uniformly good, but differences in germination, growth and seed production were observed between treatments.