STUDIES ON THE NUTRITION OF THE FORAGE LEGUMES: IV. THE EFFECT OF COBALT ON THE GROWTH OF NODULATED AND NON-NODULATED TRIFOLIUM SUBTERRANEUM L

Cobalt has been shown to have a beneficial effect on the growth of T. subterraneum, whether the plants are nodulated or not, and which is largely independent of the effectiveness of the rhizobial symbiont used. With effectively nodulated plants, an increase in the supply of combined nitrogen reduced both the nodulation (in grams per gram of root) and the haem content of the nodules. Within the ranges of concentration used, cobalt had little effect in counteracting this, which is in contrast with the results previously reported for the interaction of copper and nitrate supply.