270 MASS. EXPERIMENT STATION BULLETIN 271 



(7) Continuous tobacco gave a slightly higher percentage of total, 

 soluble, and animoniacal nitrogen, acid soluble ash and higher pH than 

 tobacco following onions or potatoes. 



In addition to the chemical studies here reported, the yield, grades, and 

 market value of Havana tobacco grown on the experiment station plots 

 under different fertilization and cultural conditions have been compiled. 



Oil Sprays. (E. B. Holland). The preparation of numerous miscible 

 oils and stock emulsions with diamond paraffin oil (a light lubricating oil) 

 and different emulsifiers has been continued and the stability against 

 stratifying and breaking on test noted. The work is time consuming as 

 it is largely on a trial and error basis'. As a whole the miscible oils 

 prepared by spontaneous methods are the most promising, easy to make, 

 and relatively inexpensive. The laboratory samples applied last spring 

 gave satisfactory results in the field. 



Tlie work should be continued witli a medium paraffin oil. 



Nitrogen Fixation in the Presence of or as a Result of the Growth of 

 Legumes versus Non-Legumes under Certain Defined Agronomic Condi- 

 tions. (F. W. Morse). This year (1930) all the plots were seeded with 

 Japanese millet. Conditions were favorable for uniform growth until 

 July 22, when a short, severe thunderstorm beat down the millet on the 

 plots fertilized with nitrogen, wliich inhibited subsequent growth up to 

 the date of cutting (August 19) and also caused a heavier stubble to be 

 left on the field. 



A comparison of the annual production with and without nitrogen for 

 both systems of cropping is presented for this and the preceding years. 

 The plots selected for comparison are adjacent to each other; Plot 9 which 

 has not received nitrogen since 1882 and Plot 10 which has received organic 

 nitrogen throughout the period. During this study the applications of 

 nitrogen liave been made in alternate years, 1921, 1926, 1928, and 1930. 

 Plot 10 received a total of 80.9 kilograms of nitrogen per acre in tiie form 

 of dry ground fish. 



Scanning the results with leguminous crops used in rotation, it will be 

 noted that clover did not respond to the use of nitrogen in the fertilizer 

 whether applied directly as in 1924 or the previous year as in 1929. Soy 

 beans, however, did respond to the direct application of nitrogen in 192'6, 

 especially in the amount of nitrogen recovered in the crop. Corn was 

 grown in the years when nitrogen was withheld, but showed some gain 

 due to the jirevious season's application. Millet in 1930 received a direct 

 treatment with nitrogen and responded, esjiecially in the yield of nitrogen 

 in the crop. 



The results with continuous non-leguminous crops show very plainly 

 their response to applications of nitrogen in the fertilizer. 



The objective of the experiment, however, was to ascertain whether or 

 not there was fixation of nitrogen in the soil in the absence of leguminous 

 ))lants. It will be noted that as the years have passed the three kinds 

 of crojis, grass, corn, and Japanese millet, without nitrogen, have gained 

 in production of dry matter and yield of nitrogen instead of decreasing as 

 one might expect if no nitrogen was being fixed. 



Similar comparative results were obtained with adjoining plots. No. 7 



1 Some ratios seem to indicate that there may be a fundamental reaction involved. 



