ANNUAL REPORT, 1946-47 7 



It is believed that the physiology of plants during the early growing period is 

 not normal under these conditions. The postulate has often been made that 

 micro-organisms instrumental in decomposing tissues containing much lignin 

 need an abundance of nitrogen and consequently rob the seed plant temporarily 

 of this element. 



Nitrogen at the rate of 0, 50, 100, 200, 300, and 500 pounds per acre in the form 

 of nitrate of soda was applied to some hay plots in the early fall and to others in 

 the spring before the plots were plowed. Tobacco was grown on these plots. 

 An improvement in the crop index was found in nearly all cases; but the higher 

 rates of 300 and 500 pounds of nitrogen did not greatly' increase the yield of to- 

 bacco over the lower rates of 100 or 200 pounds. A greater effect due to the 

 nitrogen was noted on those plots that were plowed in the early fall than on those 

 which were similarly treated but plowed in the spring. The warm early fall days 

 apparently gave the micro-organisms an opportunity to act more fully upon the 

 fiber plowed under in the mature grass. Where lime was applied, the response 

 was greater than where no lime was added. It may be concluded, therefore, 

 that the limed land served as a better medium for the decomposing micro-or- 

 ganisms than the unlimed land. 



In a similar experiment where corn was plowed under after the ears were re- 

 moved and nitrate of soda was applied, there was an increase in the yield of 

 tobacco of 100 to 200 pounds per acre. 



On plots treated similarly in every respect except that sulfate of ammonia 

 was the form of nitrogen applied, results were not so favorable as where nitrate 

 of soda was applied. 



The Absorption of Chemical Elements by Plants. (Walter S. Eisenmenger and 

 Karol J. Kucinski.) In the field, copper ions at the rate of 225 parts per million, 

 calcium carbonate at the rate of 5,000 pounds per acre, and magnesium sulfate 

 at the rate of 225 parts of magnesium per million were added to soil in which 

 rye, barley, and buckwheat were grown. There was no pronounced lowering of 

 the magnesium in the plants where copper was applied. However, when copper 

 and calcium were used together, in every case there was a pronounced increase 

 of calcium intake in all three species of plants as compared with plants which 

 grew where calcium and magnesium were applied singly or together; where copper 

 was applied alone; where magnesium and copper were applied together; or where 

 there was no treatment. There would seem to be no doubt that calcium and 

 copper together augment the intake of calcium for these three species. 



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

 Karol J. Kucinski.) Magnesium deficiency is conditioned by factors other than 

 the amount available for plants. During dry growing seasons, magnesium de- 

 ficiency is not nearl}' so evident as during wet periods. In the experimental field, 

 one of the deficient areas has received lime every year and the other has not 

 received either lime or magnesium. The symptoms of magnesium deficiency are 

 invariably more pronounced on the plot receiving no lime than on the area where 

 lime was applied. On the magnesium-deficient areas, the pH is about 4.4 where 

 no lime has been applied and about 6.9 where lime has been applied. 



In the orchards, it has been found that applications of magnesium are often of 

 no great aid in correcting magnesium deficiency. In the magnesium plots it has 

 been well demonstrated by chemical analysis that very frequently no increase in 

 magnesium or only very small increases occur in the plant tissue of perennials 

 grown on land where magnesium has been applied. This is unlike the usual 

 behavior of annuals. 



Plants frequently found as weeds in the garden, such as grasses, members of 

 the aster family, isolated cases of members of the Boraginaceae and Convolvu- 



