CROPPING SYSTEMS FOR TOBACCO 



13 



poor in quality. The corn and hay crops received, with few exceptions, the standard 

 fertilizer for such crops. The high yield of corn in 1925 was probably due to a 

 double application given that year; likewise for timothy hay in 1931. Generally 

 the corn did well and the timothy hay poorly in the rotation. In contrast, clover 

 hay did much better in the same rotation (Table 22). It is believed that the 

 strong acidity of the soil in this rotation affected the timothy more adversely 

 than it did the clover. In the supplementary experiment corn did somewhat 

 better after tobacco and hay than in continuous culture. Hay was much better 

 after tobacco than after corn. 



5. The Influence of Cropping System on Burn 



Burn tests were made on unrolled leaves of the long dark (LD) and long second 

 (LS) grades of tobacco from the different treatments. These two grades together 

 constitute more than 50 per cent of the better-quality tobacco. Each leaf tested 

 was ignited with an electric hot point at two places on each side of the midrib, and 

 the duration of the burn determined in seconds with a stop-watch. Five leaves 

 were selected from each plot after the tobacco had gone through the sweating 

 (fermentation) process. Therefore, in case of five replicated plot treatments 100 

 tests were obtained for each treatment. The average results are given in Table 5. 

 In the tests of 1930 no burn was timed beyond 60 seconds. Prior to that time, 

 the duration of the burn was recorded without limit. 



Table 5 — • Burn Tests on Sweated Tobacco Leaves. 



(Duration of Burn in Seconds) 

 Cropping System 1926 1927 1928 1929 1930 



Average 



Darks 



Continuous Tobacco : 



No cover (check) 8.2 9.4 32.5 



Manure 4..S 9.7 46.7 



Manure and tiraotliy cover 20.3 



Timotiiy cover (old series) 6.8 9.3 36.5 



Timothy cover (new series) 34.8 



Timothy cover (residual) 25.7 



Red top cover 9.3 12.0 27.2 



Rye cover 5.3 8.8 26.9 



Rotation Tobacco : 



With corn and timothy 4.7 12.7 



With corn and clover 18.2 



With potatoes and onions 6.1 5.0 23.2 



Second.s 



Continuous Tobacco: 



No cover (check) 13.1 26.1 6U.6 



Manure 11.7 25.6 63.0 



Manure and timothy cover 96.0 



Timothy cover (old series) 9.2 12 9 48.7 



Timothy cover (new series) 48. 1 



Timothy cover (residual) 48.3 



Redtopcover 15.5 22.5 48.5 



Rye cover 9.2 19.2 47.4 



Rotation Tobacco: 



With corn and timothy 23.7 313 



With corn and clover 30.5 



With potatoe.= and onions 6 5 7.8 45.0 



♦These averages not strictly comparable with those for the longer periods. 



