10 



MASS. EXPERIMENT STATION BULLETIN 339 



Average Yield per Acre 



The Reaction of Plants Grown in the Field toward the Subsequent 

 Tobacco Planted in Rotation. (Walter S. Eisenmenger and Karol J. 

 Kucinski.) It has been a conjecture of the writers that there was a possible 

 relationship between the botanical species and rate of ammonification and 

 nitrification of plant tissue and the capacity to induce brown root-rot when 

 different plants were grown in rotation with tobacco. 



All the grasses tried with the exception of red top are conducive to the occur- 

 rence of the trouble. Red top decomposes the most slowly of all the grasses 

 used in rotation. 



The Solanaceae, potatoes, tomatoes, etc., do not seem to induce the trouble. 

 They decompose exceedingly rapidly to ammonia and nitrate nitrogen. Rag- 

 weed and horseweed decompose fairly rapidly, and do not induce the malady. 



On a field this year were planted the following varieties of plants: horseweed, 

 alfalfa, Canada bluegrass, Kentucky bluegrass, sweet clover, orchard grass, 

 red clover, rye, wheat, artichoke, red top, ragweed, gladiolus, turnip, tomato, 

 pepper, cabbage, squash, sudan grass, sorghum, buckwheat, carrots, millet, 

 and seaweed (applied). The relative rate of ammonification and nitrification 

 of these plant tissues is known from previous experiments. 



In 1937, tobacco will be planted where (on four plots of each plant) these 

 plants were grown in 1936. 



Magnesium Requirements of Plants. (Walter S. Eisenmenger and 

 Karol J. Kucinski.) Parts of a field known to be deficient in magnesium were 

 used to determine the relative response and tolerance of different crops to this 

 element. A mixed fertilizer containing no calcium or magnesium was applied 

 to the entire field, and magnesium sulfate and ground limestone were added as 

 follows: Plot A — none, Plot B — magnesium, Plot C — magnesium and 

 lime, Plot D — lime. 



The differences in appearance during the growing period were marked. 

 Differences in yield, expressed as pounds per acre, are shown in the following 

 table: 



Potatoes 



Corn 



Plot Mangels Ruta- Pounds Percent- Stover Ears Buck- Barley* Oats* 



bagas per A age of Dry Dry wheat 

 Seconds 



A— None 32.231 38,287 7,492 28.85 2,544 1,918 1,611 3,458 7,092 

 B — 



Magnesium 42,390 42.430 14.481 23.81 3,755 3.746 2,037 2.824 4,705 

 C — Magne- 



siumandlime 48,167 51,474 17.435 13.22 3,310 3,033 2.278 2.025 3.078 



D — Lime 31.076 45.776 16,811 15.71 2,955 3,462 2,039 3,497 2.997 



*These crops may have been affected during the dry summer by a gravelly slope running through 

 the plots. 



