10 MASS. EXPERIMENT STATION BULLETIN 297 



2. E fleet of Cropping Systems on Quality 



Two measures of quality have been employed in this project — commercial 

 grading and the burn test. The percentage of the different grades of tobacco grown 

 under the several cropping systems are given in Tables 8-18. The percentages 

 have been combined by a method described in the appendix into a numerical 

 expression known as the "grade index." Thus, the superior grading quality of 

 tobacco sorting out high percentages of "lights," "mediums" or "seconds" is shown 

 by this index. Compare, for example, the percentages of the different grades in 

 the crops grown with manure and in rotation, Tables 9 and 16 or 17, with the grade 

 indexes for those crops. The product of the grade index by the crop yield gives a 

 single numerical expression known as the "crop index" which combines yield and 

 grading quality. Grade and crop indexes are summarized in Table 3. 



Commercial tobacco grading as practiced in the Connecticut Valley cannot be 

 reduced to an exact science. No two graders will grade a given lot of tobacco in 

 the same way. Since there were three different grading supervisors in the course 

 of the experiment, some of the differences in percentage of grades may be attribu- 

 ted to the different personalities. Perhaps a more important factor affecting the 

 variation in quality from the same treatment is that of climate. For example, in 

 1930, a year of low rainfall, both grade and yield were exceptionally high; whereas 

 in 1929, a year of exceptional drought, and in 1928, a wet season, the quality was 

 poor. The grade index was generally better for the period 1928-1931 than for 

 1924-1927, which may be attrilnited in part to the larger application of fertilizer 

 in the period 1928-1931. 



Continuous tobacco with fertilizer and manure produced the best quality of 

 tobacco, as shown by a higher grade index for this treatment for every period in 

 which a direct comparison with other treatments may be made. Red top cover 

 gave a grade index slightly better than the other cover crops, but the difference is so 

 slight that it is probably no more than a chance variation. The quality of the 

 tobacco from the three rotations was decidedly poor. The effect of the different 

 treatments on the percentage distribution of the different grades is shown in 

 Tables 8-18, and on the length of leaf within the different grades in Table 24 of 

 the appendix. Since the manure treatment gave the best grading quality of to- 

 bacco, one may set up as a standard at which to aim, the average percentage dis- 

 tribution of the grades of this crop as shown in Table 9. 



Since the crop index combines grading quality and yield into a single number, 

 particular attention should be given the crop indexes given in Table 3. Here it will 

 be seen that continuous tobacco with fertilizer and manure gave the best net result. 

 This means that the farmer would get a better financial return from tobacco grown 

 with this treatment than with any other studied, if due consideration were given 

 to quality by the bu\er. Although the yield was slightly better with red top 

 cover than with manure \\ ithout a co\er, the superior quality of the tobacco grown 

 with the manure raised its crop index above that from red top. The differences 

 of both these treatments from the check are sufficiently great to be significant, but 

 the indexes for rye and timothy cover are not significantly higher than the check. 

 The crop indexes of tobacco from the rotations are definitely low, and the others 

 are in line with previous statements. 



3. Effect o] Cropping Systems on Broii'u Root- Rot of Tobacco 



Root-rots have been known to exist on tobacco grown in the Comiecticut Valley 

 since the latter part of the last century. It has been observed that they were 

 associated with, if not the cause of, low yields in individual cases, and some have 



