10 MASS. EXPERIMENT STATION BULLETIN 449 



A greenhouse study was made to determine the effects of the cations in the 

 alkali group of the periodic table upon the absorption of magnesium by tomatoes. 

 Lithium at the rate of 30 parts per million proved toxic when applied to Merri- 

 mac sandy loam. The addition of 300 parts per million of potassium, 125 parts 

 per million of rubidium, or an equal amount of cesium had no effect on the amount 

 of magnesium absorbed, or on the degree of chlorosis of the lower leaves as com- 

 pared with a check treatment in which nothing was added. However, all these 

 treatments, as well as the check treatment, resulted in significantly less magnesium 

 absorption and less pigment production than a treatment in which magnesium 

 was added. Sodium at the rate of 300 parts per million overcame magnesium 

 deficiency to some degree as was shown by the absence of chlorosis of the leaves 

 and a slightly higher uptake of magnesium. 



Magnesium sulfate applied around apple trees at the rate of 5, 15, and 25 

 pounds per tree failed to increase the magnesium content of the leaves. 



Yields were recorded for nine vegetable and berry crops grown on plots which 

 were known to be deficient in magnesium. One plot was treated with magnesium 

 alone; a second with magnesium and lime; a third with lime alone; and a fourth 

 received neither magnesium nor lime. All plots received 1 ton per acre of 5-8-7 

 fertilizer especially prepared to contain no magnesium. Blueberries yielded 

 highest where neither lime nor magnesium was added; tomatoes and eggplant,, 

 where magnesium alone was added; beets and cabbage, where magnesium and 

 lime were added; and raspberries, peppers, string beans, and carrots, where 

 lime alone was added. 



The results of the studies on vegetables indicate the importance of magnesium 

 in vegetable fertilizers, since a high carotene content is desirable from a nutri- 

 tional standpoint. 



Tobacco Quantity and Quality Following Early Fall Application of Nitrogen 

 Fertilizer. (Walter S. Eisenmenger and Karol J. Kucinski.) When tobacco is 

 grown following such crops as corn, clovers, and grasses, which are high in lignin, 

 symptoms of brown rootrot are more likely to occur. Micro-organisms instru- 

 mental in decomposing tissues containing much lignin need an abundance of 

 nitrogen and consequently rob the tobacco plant temporarily of this element. 

 Nitrate of soda at the rate of 0, 50, 100, 200, 300, and 500 pounds of nitrogen per 

 acre was applied to some hay plots in the early fall and to others in the spring 

 before the plots were plowed. In nearly all cases, these treatments resulted in 

 increased yields and improved quality of the tobacco grown on these plots; how- 

 ever, the higher rates of 300 and 500 pounds of nitrogen did not greatly increase 

 the yield over the lower rate of 200 pounds. Those plots plowed in the early 

 fall showed a greater response to nitrogen than those similarly treated but plowed 

 in the spring. The micro-organisms apparently need the warmth of the early fall 

 to act more fully on the plant tissues plowed under. 



In a similar experiment where corn was plowed under, the yield and quality 

 of the succeeding crop of tobacco was best where the corn was plowed under in 

 the early fall. 



Chloropicrin for Tobacco Seedbed Sterilization. (C. V. Kightlinger.) Chloro- 

 picrin has been used extensively by Massachusetts- tobacco growers during the 

 last few years to sterilize tobacco seedbeds and, in general, it has been satis- 

 factory. However, in 1947, some seedbeds which had been sterilized with chloro- 

 picrin in the fall of 1946 were almost total failures. Some growers attributed 

 these failures to the presence of residual chloropicrin which had not evaporated 

 because of the low soil temperature which followed its application. Many grow- 



