ANNUAL REPORT, 1938 13 



same treatment but plowed in the spring of 1938 instead of the fall of 1937, 

 showed similar response to additions of nitrogen, but the yields in general were 

 lower. Determination of ammonia and nitrate nitrogen throughout the growing 

 seasons for the past two years showed that the rate of decomposition of the old 

 sod was faster where nitrogen was plowed under. 



Although the differences in yields and chemical analyses between the res- 

 pective treatments were not so great as those obtained the previous year, because 

 of abnormal rainfall throughout the growing season, the addition of nitrogen 

 to old sods before plowing them under seems to aid in their decomposition and 

 thus lessens their usually harmful effect. 



The Absorption by Food Plants of Chemical Elements Important in Human 

 Nutrition. (Walter S. Eisenmenger and Karol J. Kucinski.) Lettuce and cab- 

 bage were grown on soil to which the cations, sodium, potassium, magnesium, 

 and calcium, were added at the rate of 500 parts per million per individual plot. 

 The anions, chlorine, bromine, iodine, sulfate, and phosphate, were used on 

 additional plots at the rate of 200 parts per million. 



From the chemical analysis, the following increases for the aerial portions of 

 lettuce and cabbage and for the roots of lettuce were observed and recorded on 

 a percentage basis. 



Lettuce Lettuce Cabbage 



Tops Roots Tops 



Cation Increase 



CaO 6.3 16.1 16.0 



MgO 58.5 19.9 43.6 



K.^0 58.7 78.7 18.0 



NagO 37.2 41.7 55.4 



Anion Increase 



PjOg 56.6 46.5 43.0 



SOg 28.4 61.5 84.9 



CI 83 . 9 83 . 6 83 . 9 



The order of intake of potassium in cabbage and lettuce was remarkably differ- 

 ent, as was sulfur. The Cruciferae are noted for sulfur compounds. Chlorine 

 was remarkably consistent in intake for the two types of plants and the parts 

 of .each plant. It would seem that different soils cause different amounts of ele- 

 ments to be taken in by plants according to the available amounts present. 

 Also, intakes of elements by plants are dependent upon the semi-permeable mem- 

 branes, which differ in different t>'pes of plants. 



Magnesium Requirements of Plants. (Walter S. Eisenmenger and Karol 

 J. Kucinski.) A plot of land known to be deficient in magnesium was divided 

 into four sections and treated as follows: no treatment, magnesium alone, mag- 

 nesium plus lime, and lime alone. A number of different species were then planted 

 across the sections to study the reaction of each to the different treatments. 



Chemical analyses show that, with few exceptions, plants receiving magnesium 

 salts contained more magnesium in the vegetative tissue; but the application 

 of lime had no effect on the content of calcium. The composition of the seeds 

 with respect to both magnesium and calcium was relatively constant regardless 

 of treatment. However, there is some evidence that the addition of magnesium 

 salts to soil reduces the potassium content of seeds. Results showed that if 

 magnesium deficiency symptoms appear after plants have made considerable 



