540 EXPERIMENT STATION RECORD. 



ent crops on soil potash; the source, form, and consumption of potash 

 fertilizers; and the application and effects of potash salts. 



It is stated, among other things, that about 25 per cent of the potash 

 of the original rocks from which soils are derived is lost by lixiviation, 

 that which remains being quite equally distributed in the soil and sub- 

 soil. "A fertile virgin soil contains about 2 per cent of total potash, 

 or about 70,000 lbs. per acre taken to the depth of one foot;" but even 

 in such soils a part of the potash is held with such tenacity as to 

 render it practically unavailable to plants. 



The amounts of potash removed by different crops vary greatly, 

 beets probably standing first, followed in order by hay, cereals, and 

 cotton. Tobacco contains a higher percentage of potash than any 

 other common crop; then follow forage beets, potatoes, sugar beets, 

 clover hay, beans, and cereals in the order named. 



It is stated that "a soil which yields about 0.01 per cent of potash 

 to a 1 per cent citric-acid solution and contains about 0.30 per cent 

 soluble in hydrochloric acid does not usually need a potash ferti- 

 lizer. . . . Becovered marsh or swamp lauds and lands containing large 

 quantities of saud need, almost universally, potash fertilizer. The per- 

 centage of potash in soils usually rises with their content of clay. . . . 



"Lime is an important adjunct to potash fertilization, and, as a rule, 

 should be added to a soil in large quantities wherever potash is 

 applied." 



Many of the potash salts are very hygroscopic, and when applied to 

 heavy, compact soils may cause puddling, which renders the soil imper- 

 vious to water and impenetrable by the roots of plants. On the other 

 hand, on soils which are not easily puddled potash salts may be bene- 

 ficial in dry periods by reason of this power of attracting and holding 

 moisture. The same property may make crude potash salts of use in 

 protecting the crop from frosts by checking evaporation. 



Large applications of potash may retard the process of nitrification. 

 On the other hand, it is claimed that the liberal application of crude 

 potash salts, especially kainit, acts to a certain extent as an insecticide 

 or a preventive of disease. 



Experiments on the availability of fertilizer nitrogen, S. W. 

 Johnson, E. H. Jenkins, and VV. E. Brixton (Connecticut State Sta. 

 Rpt. 1896, pp. 178-201). — This is a continuation of the work of previous 

 years (E. S. K., 8, p. 387), the same apparatus and methods being used 

 as in earlier experiments. The pots as left at the end of the experi- 

 ments in 1895 were used, the undecomposed roots of the previous crop 

 being pulverized, and the following basal fertilizer added: 25 gin. 

 sodium chlorid, 1 gin. magnesium carbonate, 8 gm. calcium carbonate, 

 5 gm. potassium phosphate, and 1 gm. potassium sulphate. The crop 

 grown was corn. The nitrogenous materials used "were in each case a 

 part of the same stock from which last year's tests were made." 



