724 EXPERIMENT STATION KECOKD 



ing high-grade potash salts uud iodin from kelp, but exact costs of production 

 can only be arrived at from data obtained on a large scale, as in actual factory 

 practice. Apparently, however, extraordinary profits are not to be expected 

 owing to the limited value of the product and the lar^e amount of manipulation 

 involved in the various methods of recovery. 



"Air-dried kelp will furnish a low-grade potash fertilizer comparable to kainit 

 and containing in addition over 1 per cent of nitrogen and 50 per cent of organic 

 matter capable of furnishing humus to the soil. Objections to the use of dried 

 kelp because of the presence of sodium and chlorin are untenable, because this 

 material contains less sodium and chlorin than most of the commercial potash 

 salts now being used and is but little inferior in this respect to the highest 

 grades of muriate." 



The relation of sulphur to soil fertility, O. M. Sheud (Kentucky Stn. Bill. 

 18S (Wl.'i), pp. 5D'j-G.W). — Determinations of sulphur in a large number of 

 vegetables and fruits and other materials are reported showing widely varying 

 but, in certain cases, considerable amounts of this constituent. For example, of 

 31 varieties of tobacco grown in Kentucky only two contained less sulphur than 

 phosphorus. The larger proportion contained considerably more sulphur than 

 phosphorus; in some cases twice as much. The average sulphur content of all 

 the varieties examined was 0.458 per cent, the phosphorus content 0.302. 



The addition of sulphur (100 and ofK) lbs. per acre) or gypsum (equivalent 

 to 100 lbs. of sulphur per acre) to fertilizers containing only nitrogen, potas- 

 sium, and phosphorus produced a decided increase in yield in pot experiments 

 with tobacco on a soil containing 240 lbs. of sulphur and SCO lbs. of phosphorus 

 per acre. There were decided gains in the gro'n-th of soy beans with applica- 

 tions of sulphur, ammonium sulphate, pyrite. and ferrous sulphate and smaller 

 gains with calcium, potassium, barium, magnesium, aluminum, and sodium sul- 

 phates on a soil containing 600 lbs. of sulphur and 3,04<:) lbs. of phosphorus per 

 acre. The best results were obtained with the element sulphur. Pyrite and fer- 

 rous sulphate were applied at rates furnishing 6 lbs. of sulphur per acre; the 

 other materials in amounts supplying 100 lbs. of sulphur iier acre. The sulphur 

 content of soy beans which responded to sulphur fertilization was in all cases 

 higher than that of beans which had not been fertilized with sulphur. The 

 sulphur fertilizers were also found to increase materially the growth of turnips 

 following soy beans on the same soil. 



Clover was not benefited by sulphur fertilizers on soil from the same source 

 as that used in the experiments with soy beans. In a series of experiments with 

 cabbage on soil, from the same source, to which were added in small amounts 

 ferrous sulphid. disulphid. and sulphate and ferric sulphate and oxid. sulphates 

 and carbonates of nickel, copper, cobalt, chromium, manganese, and lithium: 

 ammonium, iwtassium. and sodium sulphocyanid : and flowers of sulphur none 

 of the sulphur compounds except potassium sulphocyanid proved beneficial. A 

 few of the substances used had no effect, while several were harmful. In simi- 

 lar experiments with mustard following the cabbage good gains in yield were 

 obtained with several of the sulphates. With radishes following mustard the 

 results were more irregular, but indicated benefit from sulphur fertilization in 

 some cases. Experiments with alfalfa in sand cultures showed that this plant 

 readily utilizes different forms of sulphur. The best results were obtained with 

 magnesium, ferric sodium, potassium, and ammonium sulphates. Good results 

 were also obtained with elementary sulphur. In nine out of fifteen cases the 

 sulphates gave better results than the carbonates of the same element. 



It was found that when sulphur was added to the soil it was rapidly oxidized 

 to the sulphate (60 to 80 per cent in four months), the oxidation proceeding 

 more rapidly in a fertile soil than iu a poor soil. Sulphur was also oxidized 



