CROPPING SYSTEMS FOR TOBACCO 9 



since there were only duplicate treatments the results cannot be treated statisti- 

 cally. It will be noted that yields from the two animal-husbandry rotations were 

 particularly low, with clover the lower. These results will be discussed later in 

 connection with brown root-rot. The results from those treatments which ran 

 for the period 1928-1931 only, can be considered mainly only in the light of show- 

 ing trends. These trends correspond rather closely with the results from similar 

 treatments for the longer period. 



Table 3 — Average Grade Index, Yield, and Crop Index of Tobacco Grown 

 Under Different Cropping Systems. 



Cropping system 



1924-1927 1928-1931 1924-1931 1926-1931 



Grade Index 



Continuous Tobacco: 



No cover (check) .319 .399 



Manure 346 .419 



Manure and timotliy cover .... .413 



Timothy cover (old series) .307 .398 



Timothy cover( new series) .... .394 



Timothy cover (residual) .... .394 



Red top cover .367* .408 



Rye cover 372* .403 



Rotation Tobacco: 



With corn and timothy .20.St .3061: 



With corn and clover .... .3151 



With potatoes and onions .284 .348** 



Yield (Pounds per Acre) 



Continuous Tobacco : 



No cover (check) 1442 1610 



Manure 1492 1711 



Manure and timothy cover .... 1674 



Timothy cover (old series) 1301 1686 



Timothy cover (new series) .... 165 1 



Timothy cover (residual) .... 1608 



Red top cover 1604* 1 743 



Rye cover 1577* 1647 



Rotation Tobacco: 



With corn and timothy 99St I 300:;: 



With corn and clover .... 1257 J 



With potatoes and onions 1330 1414** 



C;rop Index 



Continuous Tobacco: 



No cover (check) 467.7 650.3 



Manure 524.3 727.0 



Manure and timothy cover 696.1 



Timothy cover (old series) 410.9 676.8 



Timothy cover (new series) 658.0 



Timothy cover (residual) 644.4 



Red top cover 588.6* 716.7 



Rye cover 586.6* 669.5 



Rotation Tobacco: 



With corn and timothy 202. 8t 402. 9t 



With corn and clover ■I()0.4{ 



With potatoes and onions 383. .S 1<)3.()** 



* For 1926 and 1927. § 1926 and 1929 oniided. 



t 1926 omitted. **For 1928 and 1929. 



t 1929 omitted. 1 1 For 1924 - 1929. 



359 



383 



1526 

 1602 



1149§ 

 1372tt 



.390 

 .413 



1 603 

 1603 



1697 

 1624 



