225 



Kentucky Station, Bulletin No. 28, May, 1890 (pp. 13). 



Experiments with fertilizers on tobacco, M. A. Scovell, M. 

 S. — The object of the experiments was to study the questions as to (1) 

 the effect of leadingelemeuts of plant food on the production of tobacco ; 

 (2) whether commercial fertilizers can be profitablj^ used iu raising 

 tobacco on our soils ; and (3) the forms and amounts in which nitrogen 

 and potash should be applied for this clop. The soil used was a " blue- 

 grass " soil, derived from tlie lower Silurian limestone, rich in phospho- 

 ric acid, and considerably worn, having been in cultivation for many 

 years. "The year previous to that iu which the experiments with 

 tobacco were made it was in oats. The land had never been fertilized 

 except in the spring of 1888, when 100 pounds each of acid black [dis- 

 solved bone-black], muriate of potash, and nitrate of soda were mixed 

 and sowed broadcast. " 



The effects of nitrogen^ phosphoric aeid, and potash on the production of 

 tobacco. — Two series of experiments were made with similar purpose. 

 The fertilizers' used iu both were the same as those recommended for 

 soil tests at the conference of representatives of experiment stations in 

 Washington, and printed in Circular No. 7 of this Office, except that sul- 

 phate of potash was used in place of muriate. Nitrate of soda IGO 

 pouuds, dissolved bone-black 320 pounds, and sulphate of potash IGO 

 pounds per acre, were used singly, two by two, and all together on seven 

 different plats, two plats remaiuing unmanured. The size of the plats 

 was in experiment No. 1, one twentieth of an acre each ; iu No. 2 one 

 fortieth of an acre. The fertilizers were applied broadcast just previous 

 to setting the plants, M^hich in both experiments were placed 22 inches' 

 apart iu rows 3 feet wide. Tables give the total yields from the nine 

 different plats in both experiments, carefully graded to "bright," "red," 

 "lugs," "tips," and "trash." The largest total yield, and the best gen- 

 eral yield, as far as quality was concerned, was, iu the first experiment, 

 with the complete fertilizer consisting of dissolved bone-black, sulphate 

 of potash, and nitrate of soda, and in the second experiment with 

 nitrate of soda. In both experiments the plats receiving nitrate of soda 

 produced the largest yields of any plat on which a single ingredient 

 was used ; and the best general yield with any combination of two 

 ingredients was with sulphate of potash and nitrate of soda. In both 

 experiments the lowest yield, where fertilizers were applied, was where 

 nitrate of soda and dissolved bone-black were used together, and the 

 quality of the tobacco on these plants was little if any better and 

 contained a higher percentage of " trash" than that from the unmanured 

 plats. The yield with dissolved bone-black was in both instances the 

 lowest of those where single ingredients were used. In general the 

 application of fertilizers materially improved the quality of the tobacco. 



Financial results. — In estimating the values of the crops from the two 

 experiments just described the "bright" and "red" leaf were calculated 



