CROPPING SYSTEMS FOR TOBACCO 19 



is the unmeasurable but real advanUige of reducing the wind erosion of soils. 

 In the rather densely populated section of tobacco culture such wind erosion causes 

 dust storms which are a public nuisance and economic disadvantage. Cover 

 crops are a positive help in abating this nuisance. They are helpful also in some 

 cases where water erosion may be serious. 



3. The rotation experiments gave results which were quite unfavorable to 

 tobacco, although in most cases the other crops were apparently benefited by 

 having tobacco in the rotation. In a supplementary experiment, it was found 

 that corn and hay were benefited by being alternated with tobacco. When 

 alternated with tobacco, potatoes did better than when grown continuously. 

 Onions, on the other hand did not do well when rotated with tobacco. The 

 mutually unfavorable effects of these two crops appear to be due to the different 

 soil conditions required for best growth of the two crops. 



4. Tobacco grown in the animal-husbandry rotations (tobacco, corn and timo- 

 thy or clover) was so poor in yield and quality as to rule this rotation definitely 

 out of consideration as practicable for the Massachusetts portion of the Connecti- 

 cut Valley. Results were about equally poor with clover and timothy as the sod- 

 forming crop. The crop index for the rotation which includes timothy was 302.9 

 compared with 438.4 for the cash-crop rotation, 559.0 for continuous tobacco 

 without co%-er or manure, and 625.6 for continuous tobacco with a manure supple- 

 ment. From these results it appears advisable for farmers who wish to run a 

 livestock enterprise in connection with tobacco growing to keep tobacco out of any 

 rotation including corn, timothy, and clover. 



5. Associated with the animal-husbandry rotation was an injurious effect on 

 tobacco which manifested itself by producing more or less dwarfed or stunted, 

 spindling tobacco with an abnormally dark green color, and causing abnormal 

 w^ilting in hot dry weather. This effect or condition of the tobacco is known as 

 brown root-rot, because of the brown, decayed appearance of the roots. This 

 condition was found to vary from season to season. In wet seasons brown root- 

 rot is usually worse than in dry, and may be a contributing cause of the generally- 

 low production in this Valley in wet years. 



6. Manure as a supplement to fertilizer applied to tobacco in continuous cul- 

 ture was found to be beneficial. Although the yield was slightly lower than that 

 from the red top cover, the quality of the tobacco was so much superior that the 

 crop index was raised appreciably above that of red top. The results of 1932 are 

 even more definitely in favor of the manure supplement. 



7. Thus, these experiments present a rather convincing argument for the use 

 of a moderate quantity of manure as a supplement to commercial fertilizer. 

 The advantage from manure lies largely in its effect on quality. The use of a 

 red top cover conies second as a means of producing good quality ot tobacco, and 

 is a much more feasible cropping system for most Valley farmers on account of the 

 scarcity of manure. It is quite possible that a combination of the two systems 

 could be worked out, which would include the good points of each, and be suitable 

 for Connecticut Valley farmers. 



S. The cropping systeius studied in this experiment have i)r()duced little or 

 no change in the soil conditions. Continuous culture of tobacco without the 

 plowing in of a cover crop caused the greatest increase in acidity, which was only 

 0.5 a pH unit. The use of cover crops, the rotation, and manure, tended to stabilize 

 the reaction of the soil. It was only in case of the cash-crop rotation where lime- 

 stone was used for the benefit of the rotation that the acidity of the soil was re- 

 duced. 



