Show FARM TOPICS LL DIET OF LEGUME IS VITAL FACTOR can detect distress signs when food Is lacking by E E DE TURK P r fessor of el soil fertility college of cf A gri culture university of illinois ois legumes like other crops fly unmistakable distress signals when their diet lacks important plant food elements observations made in the past cropping season indicate yet they frequently show these nutritional deficiencies by slow growth rather than by any specific abnormalities mali ties of form or color they are likely to produce undersized plants which are normal in appearance otherwise ordinarily the early symptoms of plant food hunger take the form of changes in color the most common color symptom results from or loss of the green color this may be followed by the death of the affected area the may consist of paling of the ordinary green color or the appearance of various shades of yellow or even white dots and patches in general the lack of one or more of the three major plant food elements nitrogen phosphorus and potash will result in ill health for the crop nitrogen deficiency results in slow growth of the legumes a decrease in the branching of the plants and smaller plants at maturity these may occur without the appearance of specific symptoms and have little value to the farmer or agronomist attempting a diagnosis severe nitrogen deficiency often causes mild in which the leaves gradually become pale green with a yellowish tinge rather than distinctly yellow the usually spreads evenly over the entire leaf surface A lack of phosphorus manifests itself in slow growth the legume plants remain small and undeveloped flowering and seed production tend to be delayed and a bluish green tinge may develop in the leaves but there are no specific symptoms that can be used with assurance for purposes of detecting phosphorus deficiency of all the symptoms observable in legumes those of potash hunger are probably the most outstanding and easily recognized broad leaved legumes such as the soybean show evidence of insufficient potash by irregular yellow mottling around the edges of the leaflets the discolored areas soon merge forming a continuous yellow border around the tip and along the sides but rarely around the base death of the area that first became mottled follows promptly along ong with a downward cupping of the leaf edges then the dead tissue falls out giving the leaflet a ragged appearance |