SOILS FERTILIZEKS. 123 



of sodium, potassium, and ammonium are lesst active. The acids are stronger 

 tlian any of tlieir divalent salts but the trivalenr salt, aluminum sulphate, is 

 stronger than any of the acids. Nitric acid is the strongest, hydrochloric second, 

 and sulphuric third. Likewise the nitrates and chlorids are stronger than the 

 sulphates." 



The cohesion of the soil particles, the apparent specific gravity of the soil in 

 most cases, and the hygroscopicity with but very few exceptions were increased 

 by the addition of salts. The vapor pressure was lowered in most instances 

 but it is stated that this can not be explained from a consideration of the sur- 

 face tension of the added salts. 



The influence of radio-active earth on plant growth and crop production, 

 H. H. RusBY (Jour. N. Y. Bot. Qarcl., 16 {1915), No. 181, pp. 1-23, pis. 10, figs. 2, 

 8ci. Amcr. Sup., 79 {1915), Nos. 2048, pp. 216-218, figs. 9; 2049, pp. 228-230, 

 figs. 12). — Finely powdered extracted radium ore containing from 2 to 3 mg. 

 of radium per ton was used at rates of 25, 50, 100, and 200 lbs. per acre in mix- 

 ture with 200 lbs. per acre of "ordinary fertilizer" on a variety of crops 

 grown in window boxes, in a greenhouse, and in field plats at different places. 



The general conclusion is that "nearly all, if not all, field crops gave an 

 increased yield under the influence of the proper amount of radio-active fer- 

 tilizer," the largest increase observed being 335 per cent. Thje greatest gains 

 reported were obtained with applications smaller than 200 lbs. per acre. Dif- 

 ferent plants and families of plants showed varying susceptibility to the radio- 

 active fertilizer. " Members of the Cruciferse or mustaxxl family, comprising 

 mustard, rape, cabbage, cauliflower, sprouts, kale, kohl-rabi, turnips, and 

 radishes were greatly benefited. So were the Cucurbitacere, comprising the 

 pumpkin, cucumber, squash, and melons; in fact, more so than any others. 

 The Graminefe, or grass family, comprising hay, corn, sugar cane, sorghum, 

 and lawn grass, was enormously benefited. . . . The effect on a second Crop on 

 the same ground was greater than on the first. . . . The effect upon germina- 

 tion, when small amounts are used, was to increase the percentage of seeds 

 germinated and to accelerate the process. The earliest effect of radium is to 

 increase the root growth. Often the stem growth will be retarded for a time, 

 but will later undergo a great acceleration. A given amount of sunlight has 

 produced a greater amount of growth when radium was used, and the same 

 amount of food production has resulted from a smaller amount of green tissue, 

 or tops in case of the greenhouse radishes. An increased tendency to branch- 

 ing has been observed when a large amount of radio-active fertilizer is applied 

 to the soil. 



" Perhaps the most important effect of radium was that of impioving the 

 edible properties of the product. Potatoes were more mealy. Root crops were 

 remarkably tender, sweeter, and of finer flavor. Beets, carrots, onions, sweet 

 corn, and similar vegetables were markedly sweeter. Tomatoes were also 

 sweeter and chemical analysis showed them to contain less water and more 

 sugar. Radium-grown string beans and peas were peculiarly sweet." 



Investigations by others in the same line are reviewed. 



Radio-active ores and plant life, H. Bastin {Sci. Anier., 112 {1915), No. 

 15, p. 335, fig. 1). — Brief reference is made to expeiiment-s with radio-active 

 materials conducted by M. H, F. Sutton, the English seedsman. These experi- 

 ments were made with ore containing radium as well as with residues from 

 radium manufacture. The crops experimented with included peas, radishes, 

 lettuce, tomatoes, nasturtiums, rape, clover, and various flowering annuals. 

 The amount of radio-active materials used varied from 1 part in 12 to 1 part 

 in 2,240 parts of soil. 



98262°— No. 2—15 3 



