ANNUAL REPORT, 1940 11 



tractives and ash decreased. Those components which are most resistant 

 to the action of bacteria and fungi are the ones which increase with ma- 

 turity. 



When tobacco followed these plants, the yields were lowest, both m 

 quantity and quality, on those plots where the preceding crop had been 

 allowed to mature. 



The Absorption by Food Plants of Chemical Elements Important in 

 Human Nutrition. (Walter S. Eisenmenger and Karol J. Kucinski.) If 

 certain chemical elements are added to the soil in abundance, they are 

 taken in by some kinds of plants in amounts larger that the normal growth 

 and metabolism of the plants require. This is sometimes referred to as 

 "luxury consumption" of elements. Other elements, however, are taken 

 into the plants only in amounts needed. In this experiment, lettuce and 

 cabbage were grown on a soil to which the cations, sodium, potassium, 

 magnesium, and calcium, and the anions, chlorine, iodine, bromine, sulfate, 

 and phosphate, were added separately to plots in quantities known to be 

 far in excess of normal plant requirements, but not in sufficient quantity 

 to be toxic. 



The analyses show that the intake of all cations was substantially in- 

 creased and that the increases of magnesium and potassium were greater 

 than those of calcium and sodium. Thus, magnesium and potassium are 

 much more nearly in the "luxury consumption" class than either calcium 

 or sodium. 



Phosphorus was increased in the roots about twice as much as in the 

 tops, while the greatest increase of bromine and iodine was in the tops. 

 Bromine and chlorine showed the highest percentage increases of any of 

 the elements studied. Sulfur was increased substantially in both tops and 

 roots of lettuce but not in cabbage. Cabbage is noted for its sulfur con- 

 tent; but sulfur is not a "luxury consumption" element, and the cabbage 

 takes in only its normal amount regardless of the presence of an excess 

 of the element in the soil. 



The Intake by Plants of Elements Applied to the Soil in Pairs Com- 

 pared to the Intake of the Same Elements Applied Singly. (Walter S. 

 Eisenmenger and Karol J. Kucinski.) Results of other experiments have 

 shown that the application of elements to soil tends to increase their 

 quantity in the plant. In this experiment it was decided to study the 

 intake by plants of elements added two at a time to the soil in quantities 

 known to be excessive but not toxic. The materials used supplied calcium, 

 potassium, and sodium at the rate of 250 parts per million of soil, and 

 lithium at the rate of 100 parts per million. Lithium is exceedingly toxic; 

 therefore it was added several months before seeding. 



This study is in its initial stages, but analysis of cabbage, celery, and 

 lettuce plants indicates that when sodium and calcium salts were applied 

 together to soil, the calcium intake of the plants decreased. Similar re- 

 sults were obtained when potassium was added with calcium, but the 

 percentage intake of potassium increased. Plants can tolerate lithium 

 only in small quantities; but when potassium and lithium were added 

 together to the soil, the intake of lithium was decreased. When cabbage 

 plants were grown in soil treated with both potassium and sodium, the 

 potassium intake was definitely decreased, which indicates that sodium can 

 apparently replace potassium in plant nutrition. 



