OCR Text |
Show Manganese Is a Poison, Also Tonic for Plants A substance that has been generally accepted as a poison to plant life has been shown by later experiments to be a valuable tonic. The substance is manganese, a chemical element somewhat some-what resembling iron. When lacking or present in too small an amount in the soil, plants have a sickly yellow-green yellow-green color. When such plants are fed with manganese sulphate in water to the extent of eight parts in a million mil-lion they become vigorous and healthy. Their yield has been increased as much as 215 per cent. If the manganese man-ganese is increased slightly above this amount It becomes toxic and the plants become unhealthy. Within this narrow margin manganese Is a tonic for plant life and outside it becomes a poison. "Manganese is not a panacea for any and all cases of plant starvation which the usual ration of nitrogen, phosphorus and potassium plant foods will not cure. The crop may be in need of minute traces of soluble compounds com-pounds of boron, copper, zinc and possibly pos-sibly of other elements not yet definitely def-initely known as required elements in plant nutrition," says an official of the office of experimental stations of the United States Department of Agriculture. |