The effect ofRhizobiuminoculation on white clover in improved hill soils in the United Kingdom

Abstract

The benefits to establishment and growth of white clover cvs Aberystwyth S.184 and Grasslands Huia of inoculation with three strains of Rhizobium trifolii, using the peat or liquid inoculum techniques, were investigated during 1975-8 on improved hill soils ranging from brown earth through dry and wet peaty podzol to deep peat.Inoculation induced positive response in either number of seedlings, plant cover or dry-matter production in 18 out of 139 comparisons, had no effect in 118 and produced a negative response in three. Most of the positive responses to inoculation were at sites with wet peaty podzol or deep peat soils but of the five sites where increase in clover D.M. production was found in the first harvest year one was a brown earth. The positive agronomic responses occurred only when the proportion of plants with nodules was high and where a substantial proportion ( > 50 %) of the latter contained introduced Rhizobium strains at least in the year of sowing. The three negative responses were in numbers of seedlings on one brown earth and two dry peaty podzol soils and with the Huia cultivar only. Despite lack of statistical significance at individual sites the dominant overall trend was for inoculation to enhance seedling establishment and the early growtli of white clover in all soil types.On one brown earth and one dry peaty podzol soil there was some evidence that spraying the Rhizobium on to emerging white clover seedlings was more beneficial, at least in microbiological terms, than the customary peat inoculum procedure.The incorporation of even a small amount of nitrogen (30 kg/ha) into the seed bed at the time of sowing adversely affected germination, establishment and growth of white clover in some soils. Sometimes the effects of this nitrogen persisted into the first harvest year.

A survey of clover and Lotus rhizobia in Northern Ireland pasture soils

“…The highly effective strains of clover rhizobia isolated in these studies may be useful in such inoculant selection programmes. These findings support the recommendation of Jones & Burrows (1969) and Newbould et al (1982) for the routine use of Rhizobium inoculants when sowing white clover, and also marsh trefoil in improved acid soils to maximize productivity from these pastures.…”

“…Previous reports (Gibson et al, 1975;Sherwood & Masterson, 1974) have stressed the importance of using the correct host in assessing the effectiveness of indigenous rhizobia. The clover variety used in this study was Grasslands Huia, which is well suited to hill land conditions (Newbould et al, 1982), and the Lotus variety was G4705 (Grasslands Maku) which has shown potential in Scottish hill trials (Charlton, 1975). The rhizobia isolated using these host plants may not be representative of the soil population, but they do represent the strains which will form nodules on agricultural varieties of their particular hosts.…”

“…This suggested that the effectiveness of rhizobia in these soils could be improved either by increasing the pH or soil base status, or by inoculating with effective strains of Rhizobium. The response by white clover to inoculation in hill soils has been variable (McLoughlin & Dunican, 1981; Mytton & Hughes, 1984;Newbould et al, 1982), possibly due to competition from indigenous rhizobia or other edaphic factors. The aims of this survey were (a) to assess the number and effectiveness of indigenous clover and Lotus rhizobia from a range of sites covering the main soil types in Northern Ireland and (b) to examine the relationship between the rhizobia and the chemical properties of the soils from which they were isolated.…”

White clover seed inoculation and coating in New Zealand

“…Effective rhizobia have been successfully introduced into UK low-fertility peat or peaty podzol soils where strains ineffective on white clover are widespread (Holding & King 1963). However, even on these soils responses to inoculation were inconsistent and only occurred where the inoculant strains form >50% of the nodules (Newbould et al 1982).…”

The response of white clover to different strains ofRhizobium trifolii in hill land reseeding: A second trial

“…Newbould et al 8 recorded a positive response in only 18 out of 139 comparisons made a different locations. Many of the hill soils of Britain are known to have deficient populations of rhizobia 1, 2, 3, 9,10 and yet commercial inoculation of white clover in hill reseedings is still uncommon.…”