Root Action and Bacteria

Abstract

I HAVE always carefully looked for, but never found, any retardation of germination in our experiments. The young plants all come up at about the same time, and make equal progress for some weeks; then the plants on the heated soil take on a greener colour, become larger in the leaf and thicker in the stem, and ultimately make about 100 per cent, more dry matter than the control plants in unheated soil. There is no doubt, I think, that bacterial action is involved, because the yield is depressed when I inoculate the heated soils either by watering with unsterilised well water or by adding small quantities of unheated soil. A chemical change in the soil compounds must also be involved, because of the increased “availability” of the nitrogen and phosphorus compounds indicated by the analyses quoted in my earlier letter. All non-leguminous plants we have tried so far have shown similar behaviour.