Contemporary work on soil microbiology may show that manganese and other essential nutrients are perhaps most important in their functions for the preservation and balancing of microbial life and actions in soils. There is where tree nutrition must begin; whatever is neglected in soils can at best only temporarily be adjusted afterwards. After all, deficiency symptoms on foliage show lack of soil fertility, and while we should welcome them for their diagnostic value, our corrective measures to be most economical must be taken on soils. Transmission of Inorganic Nutrients from Soils to Plants to Animals Soil analysis and plant tissue tests both have their value, but also their limitations. Many laboratories and experiment stations are equipped to make rapid soil tests, and some engage in leaf analysis. It is important that they be correctly interpreted. For instance, at the Citrus Experiment Station, Riverside, California[22], bark and leaves were collected from healthy and diseased Persian Walnuts. They were analyzed for calcium, magnesium, inorganic phosphate, manganese and iron. A higher percentage of ash was found in the diseased than in the healthy bark, and calcium, magnesium, manganese and inorganic phosphates were also generally higher. It would be a fallacy I think to conclude therefrom that these elements were not necessary, or were present to excess. They were probably present because they had failed to function properly, due to changes in weather, excessive rains or droughts, and could not eliminate themselves. We must consider the results from the functions of the essential elements, and discard the popular belief that inorganic nutrients in soils are transmitted from soils to plants, and therein contained for the express purpose of satisfying the need of animals and humans[23]. The plant has only one purpose to perform which is to grow and to reproduce itself, and such is the case with all other forms of life.