The “inoculation” of lucerne (Medicago sativa, L.) in Great Britain

1. The paper discusses experiments laid down at 39 centres in Great Britain to test the value of seed inoculation for lucerne. 2. The seed was inoculated by treating it with a suspension of the nodule bacteria in skim milk containing 0·1 per cent, calcium di-acid phosphate, the method developed by Thornton and Gangulee. 3. In the west and north of England the treatment greatly benefited the lucerne and often enabled a crop to be obtained where the untreated lucerne failed. At 12 centres in this area at which the crop was weighed, inoculation increased the yield by over 20 per cent, in all cases save one, where spread of the bacteria vitiated the result. 4. The improvement sometimes showed itself as an increased yield and sometimes as an increase in the nitrogen content of the hay. In most cases both these effects were produced. 5. In the midland and south central counties inoculation usually produced a temporary improvement, the untreated plant eventually catching up with the inoculated. The effect of inoculation is very much greater where the young lucerne has to compete with a cover crop. Weight results from 8 centres in this area showed increases from inoculation of over 20 per cent, in 4 cases, smaller but significant improve-ment in yield or nitrogen contentin 3 cases, and no significant effect in one case. 6. In East Anglia and Kent untreated lucerne usually develops plenty of nodules. An exceptional condition occurred in a trial at Tunstall Heath, Suffolk, on sour light land, where liming and inoculation produced a fair plant although the uninoculated lucerne developed no nodules and failed. 7. There is evidence that, when the seed is inoculated, the chances of success with lucerne are on the whole as good in the west and north of England as they are in the south-east. 8. In a number of trials sown in 1926 better results were obtained by sowing the seed in a light cover crop in spring than by sowing in June or July. RESP-60