404 



The effect of potassium salts on tlie plant depends on the form of the 

 fertilizing salt and the soil on which it is used^ The question arises here 

 as to the part played by the accessory salts incorporated in the soil with 

 the addition of potassium. At present, kainit and the 40 per cent, potas- 

 sium salt are used more extensively, ^^'^ith kainit, 3^ cwt. should be used 

 if one desires to add as much potassium as is present in one cwt. of 40 

 per cent, potassium salt. Among the accessory salts introduced in the 

 kainit, sodium chlorid i)lays a prominent role. Besides this, magnesium 

 sulfate and magnesium chlorid come under consideration. The individual 

 plants behave very differently with sodium chlorid. Its effect on sugar 

 beets is very good, but potatoes are very sensitive to it". The results with 

 sugar beets, however, are rather deceptive. According to Aducco ard 

 Wohltmann's exj^eriments, the amount of beet substance harvested is in- 

 creased, but the quotient of purity and the sugar content are reduced. 



On account of the accessory salts, Schneidewind and Ringleben"' tested 

 raw potassium salts with different potassium compounds as contrasted w ith 

 the highly concentrated forms. It was shown for a mixture of clover and 

 grass, and for oats, sugar beets and potatoes, that kainit was superior to 

 potassium chlorid and potassium sulfate, if sufficient amounts of calcium 

 carbonate were present. If these were lacking, opposite results were ob- 

 tained. If the slightly soluble gypsum was used, instead of calcium car- 

 bonate, kainit proved to be especially injurious for the mixture of clover 

 and grass, but less so for oats. In potatoes the action was favorable if the 

 soils were poor in potassium. With an increase of potassium, the effect of 

 excess became evident, i. e. the starch content was lowered. Szollema'* 

 found that the decrease of starch, effected by the chlorid, which is connected 

 with a greater abundance of water, was somewhat greater in the varieties 

 of potatoes naturally rich in starch than in those poor in starch. 



When plants are very sensitive to the chlorine compounds of the raw 

 potassium salts, as, for example, kainit, the loss of potassium by its partial 

 leaching from the soil during the autumn and winter, is really an advantage 

 in so far as many of the dangerous accessory salts (sodium chlorid and 

 magnesium chlorid), are washed out at the same time; therefore, while 

 actually less potassium remains in the soil, it becomes more effective, be- 

 cause it is in a purer form. This leaching of the potassium must be taken 

 into consideration in soils with only small amounts of calcium and other 

 such absorbents, as, for example, in light, sandy, and moor soils'. 



Concerning the disadvantageous effects of potassium fertilization on 

 cultivated plants, other than those already named, we will mention further 



1 Blatter fiir Zuckerriibenbau 1905, p. 62. 



2 Blatter fur Zuckerriibenbau 1905, p. 89. 



3 Schneidewind, W., and Rinsleben, O., Die Wiikunf? der Kalirohstoffe un<l 

 der reinen Kalisalze bei verschiedenen Kalkformen. Landwirtsch. Jahrib. 1904. 

 A'ol. XXXIII, p. 353. 



■i Szollema, D., Vber den Einfluss von Chlor- und anderen in den Stassfurter 

 Rohsalzen vorkommenden Verbindungen etc. cit. Centralbl. f. Agrikultur-Chemie 

 1901, p. 516. 



5 Schneidewind. Auswaschen des Kalis im Winter. Zeitschr. (I. T>andwirt.schafts- 

 kammer f. Schlesien 1904, No. 14, p. 471. 



