FIELD CROPS. 335 



indicates tbat the principal factor favoring the burn is the potash in excess of 

 the amount required for combining with the mineral acids." 



The effects of potassium, calcium, magnesium, and mineral and organic acids 

 of tlie ash on the bui'ning qualities are discussed and the character of the ash, 

 together with the relation of organic constituents to the burning qualities, is 

 described. 



In the summary of his work the author points out that flu* lire-holding capac- 

 ity is dependent primarily on tlie content of potash combined with organic acids; 

 that lime in general does not affect the fire-holding capacity, but is an essential 

 factor in the production of good ash; that large amounts of magnesia tend to 

 injure the capacity for fire-holding; that chlorin injures the burning (lunlities, 

 but seldom is present in suflicieut quantities to do any serious harm ; and that 

 sulphates in general injure the burning qualities, but that the effects are less 

 marked when all the sulphuric acid is combined with potash. It is further 

 pointed out that so far as known none of the organic constituents of tobacco, 

 with the possible exception of the so-called tarry acids and the albuminoids, 

 exert a veiy important influence on the burn. 



"From these conclusions it appears that the principal objects to be attained 

 in efforts to improve the burning qualities of tobacco by breeding and by 

 improved methods of production, especially in the use of the proper fertilizers, 

 are (1) a relatively high content of potash combined with citric and malic acids, 

 with a minimum amount of inorganic salts, especially chlorids and sulphates; 

 (2) a moderate content of lime; (3) a comparatively small percentage of 

 magnesia, and (4) a low content of organic nitrogenous compounds, more 

 especially the albuminoids or proteids." 



The improvement of fire-cured tobacco, G. T. McNess. E. II. Mathewson 

 and B. G. Anderson {Yiryinla Sta. Bui. 166, pp. 191-23J,, figs. 8).— This bulle- 

 tin is based on the results of cooperative work of the Virginia Experiment Sta- 

 tion and the Bureau of Soils of this Department. The plan of the experiment 

 as well as the results for 1004 have already been noted from another source 

 (E. S. R., IS, p. 2.35). The cultural history of the dark shipping type of tobacco 

 in Virginia, the climate and soil required by the crop, and the results of experi- 

 ments made in ir)04-100r), inclusive, are discussed, and the methods of cultivat- 

 ing and handling dark tobacco which the investigators found to be best in their 

 general experience as well as in their experimental work are described. 



The work was carried out on 3 one-acre plats. Plat No. 1 received 400 lbs. 

 of factory mixed fertilizer containing 12 lbs. each of ammonia and jjotash and 36 

 lbs. of phosphoric acid. Plat No. 2 was treated with 850 lbs. of a home mixture 

 furnishing 73.5 lbs. of ammonia, 57 lbs. of phosphoric acid, and 75 llis. of potash, 

 and plat No. 3 was given 1.700 lbs. of a home mixture supplying 15:; llis. of 

 aunuonia, 100 lbs. of phosphoric acid, and 125 lbs. of potash. 



In the fall of UH;»4 the plats were sown to rye as a winter cover crop. On the 

 2 heavy fertilized plats the rye had grown loo tall for turning under, and hence 

 rye hay was made before plowing. Owing to good moisture conditions, early 

 transplanting, a healthy continuous growth, and the improvement in soil fer- 

 tility resulting from the more intensive methods employed, good yields were 

 secured in 1005. Plat No. 1 yielded S42 lbs. of toliacco, produced at a cost of 

 •1:45.04 and sold for $00.13. Plat No. 2 produced 1.20G lbs. of tobacco and 1,000 

 lbs. of rye hay. at a cost of .$08.47, which sold for $104.01 ; while plat No. 3 

 yielded 1,527 lbs. of tobacco and 2,000 lbs. of rye hay, produced at a cost of 

 $!X).77 and .selling for $1.34..50. Disregarding the rye crop, plat No. 1 showed a 

 profit of $15.10, plat No. 2 of $.30.34, and plat No. 3 of .$40.42, as compared with 

 $4.64, $19.94, and $28.41, the profits, respectively, the year before. 



