10 MASS. EXPERIMENT STATION BULLETIN 394 



Table 6. — Effect of Ammonium Hydroxide, and Interval Between 

 Soil Treatment and Subsequent Seeding, on Stand of Beet Seedlings 



Relative Number of Plants 

 Time Interval Between Which Lived 



Soil Treatment and 

 Seeding 



days. . 

 3 davs. . 

 5 days. . 

 7 days. . 

 10 days. 

 12 days. 

 14 days. 



There was a strong odor of ammonia when ammonium su'fate was worked into 

 a relatively moist soil which had previously been limed. Ammonium suUate, 8, 

 10, or 12 gm. per square foot, thus applied to soil 24 hours before seeding, gave 

 good results in soil with an initial pH value of 7.0 but had little or no effect on 

 damping-off in scil with an initial pH value of 5.9 (see Table 7). Growth of cu- 

 cumber and cress, but not ot beet and lettuce, was, in this case, somewhat retarded 

 by 12 gm., not by the lighter applications. 



Table 1. — Fesults With Ammonium Sulfate in Soil of the Different 



pH Values Named 



Ammonium Sulfate 



Relative Number of Plar»ts Which Lived 



None Ccherk) 200 100 



8 gm. per square foot . . . 

 10 gm. per square foot . . 

 12 gm. per square foot. . 



None (xhetrk) 29 



8 gm. per square foot. . 

 10 gm. per square foot. 

 12 gm. per square foot. 



In other experiments, a mi.xture of one part (by weight) of ammonium sulfate 

 and two parts of hydrated lime was prepared. Both were dry and there was- 

 practically nc trace of the odor cf ammonia. The mixture was stored in tightly 

 stoppered glass containers and, after 1 week, worked into soil at such a rate that 

 each square foot of scil received 10 gm. ammonium sulfate and 20 gm. hydrated 

 Hme. There was a strong odor of ammonia when this mixture was applied to 

 slightly moist soil. This treatment, applied immediately before seeding, slightly 

 retarded the growth ol all species and interfered with the germination of seeds 

 of cabbage, eggplant, and tomato; but it lessened the severity rf damping-oflT 



