L A Maynard

Abstract: MOREHOUSE and Mayfield (1946) reported briefly that 3-nitro-4-hydroxyphenyl arsonic acid “had remarkable growth stimulating properties” for chickens and turkeys when given in the drinking water at sub-coccidiostatic levels. This surprising finding was subsequently extended by Morehouse (1949) for direct addition to the diet, and was fully confirmed by Bird, Groschke and Rubin (1949). Experience by a number of investigators has indicated that arsanilic acid and sodium arsanilate are also effective in stimulating growth of chickens, turkeys, and hogs. Presumably one action of the phenylarsonic acids is similar to that of antibiotics—in some way altering bacterial metabolism in the tract to favor improved nutrition of the animal. Arsenic compounds have long been used in the practice of veterinary medicine as tonics to improve the general well-being and appearance of animals. Although the use of arsenic trioxide and the less toxic cacodylates has often been directed to the treatment of secondary . . .

Abstract: The mineral composition of plants is a function of many factors, such as difference in soils, use of soil amendments or fertilizers, and rainfall and other climatic influences. These factors overlap in their effects or work simultaneously. One factor may influence another. Thus, the effect of climate on the plant is partly direct and partly the result of the development by climatic factors of certain soil characteristics. Differences in these factors will naturally operate to modify the mineral composition of the plant in different ways. For example, it is possible (a) for the mineral composition of two plants of the same variety growing in different soils to be significantly different without there being any important difference in their size or the distribution of their parts, such as leaf, stem or seed head; (b) for the growth (yield) of plants of the same variety to vary in different soils without any important differences in the proportions of the parts of the plants; (c) for two plants of the same variety growing in different soils to have quite different distributions of leaf, stem or head; and (d) for environmental factors to so modify the quantities of plant constituents such as protein, carbohydrate, lignin and cellulose as to influence the percentage distribution of other constituents, as by a deposition of starch with a consequent reduction in the percentage composition of the mineral elements. The properties of two soils may be such as to modify the natural flora and thus to produce plants quite different in mineral composition. The evaluation of the influence of these factors on plant composition is still proceeding, and much valuable information of fundamental importance is being obtained. The nutritional diseases of animals which have been traced to soil characteristics may be divided into two general classes. The first,

Abstract: 1. In the pineapple plant a low reserve of nitrate was found adequate for greatest possible yields of fruit when carbohydrates were low. In contrast, when carbohydrates were high maximum production was not obtained unless the plants were essentially filled to capacity with nitrate. In practically the same location a difference of 75 per cent in nitrogen requirements was found in successive years (37). 2. When the concentration of carbohydrates is low and relatively little nitrate therefore supplied, phosphate is freely absorbed, even from soils rather low in phosphorus. In the same site under environmental conditions more favorable for carbohydrate accumulation more nitrate is needed. With higher nitrate there is a proximately corresponding suppression of phosphate absorption, so that it becomes necessary to apply phosphate. 3. The required level of nitrate nutrition, which varies with opportunity for carbohydrate accumulation, is intimately associated with potassium requirements. Under field conditions i...

Abstract: The nutritive values of food crops and the factors which may modify them are subjects of increasing interest. In recent years vitamin and mineral constituents of plants have been used to evaluate some aspects of nutritive value, and the importance of a variable supply of minerals from plant sources in animal nutrition has been discussed by Maynard (15). During the summers of 1941 and 1942, extensive experiments have been conducted at this laboratory on the effects of varying the relative proportions of macro-nutrients1 supplied to tomato plants on the vitamin content of tomato fruits (6, 11). Although variations in the mineral constituents of the tomato fruit are of relatively minor nutritional importance (10), studies relative to mineral composition were made to aid in an understanding of the physiological processes involved in mineral absorption by plants. In soil studies of the mineral nutrition of plants, Jenny and Ayers (12) have clearly distinguished two aspects of the problem : 1. Soil colloidal phenomena as they are influenced by fertilization and as they in turn influence the composition of soil solutions ; and 2, the absorption and accumulation of the nutrients by plants from the soil solution. For convenience, they have termed the second aspect "the biological accumulation phase by root hair cells." More exactly this aspect might include the localized retention of ions by the living system. Since the cytoplasmic constituents of any organism are changing continuously, chemical analysis of any organ at any given interval can only be empirical. Investigations with artificial culture solutions of known composition have been profitable in studying those empirical relationships involved in ionic absorption by plants. Such factors of nutrient composition as the presence of essential ions, the relative concentration of the constituent ions, the osmotic concentration of the solution, the reaction of the medium, and the total quantity of the nutrient available to the plant can be varied over wide ranges under carefully controlled conditions. It is the purpose of this paper to present data concerned primarily with the mineral composition of tomato plants as it is influenced by the composition of the nutrient medium with special attention given to ionic interaction. In many investigations of the effect of changes in nutrient supply on plant composition, nutrient solutions of fixed composition were utilized to ? The term macro-nutrients as used in this paper refers to the six nutrients (Ca, K, Mg, N03, S04, and P04) in contrast to the micro-nutrients (Cu, Mn, B, Zn, Mo, and Fe). The distinction between these two groups of nutrients is based upon the fact that the former group is needed by the plants in much greater amounts than the latter group.