21 Gisiger: Deficiencies Caused by Excesses 



The nature of the injurious effect of overliming acid soils.— 

 In earlier tests with an acid soil, which was not quite impover- 

 ished, it was ascertained that the damage from overliming is 

 greatly reduced, when the limed soil is leached for some time 

 (Gisiger, 1944). Based on this experience, the following test 

 was made: An amount of acid soil was divided into 4 parts, each 

 of which was limed wdth increasing quantities, sc. 0.5, 3, 7 and 

 24 grammes CaO per kg soil. The well-mixed soils were put into 

 large vessels and watered for several months to leach them. After 

 drying a little the soils were put into test pots in which white 

 mustard was sown. Before sowing, all the pots received the same 

 P N K manuring, to which 16 different test-dressings were added 

 viz.: lime in various forms and quantities; a manure with boron, 

 manganese and potassium, the latter as a hydrate (lye). The 

 results lead to the following conclusions: 



1st series (0.5g CaO/kg soil).— On a very acid soil growth can- 

 not be improved by a supplementary manuring with calcium chlo- 

 ride and gypsum, if the anions Cl~ and SO4"" are not washed out. 

 By liming a very acid soil with calcium hydrate and carbonate, 

 the same effect can be observed. The quantity of potassium hy- 

 drate used, i.e., 2 grammes and 4 grammes per pot, was not 

 enough to neutralize sufficiently the acidity of the soil. The 

 dressing of boron and manganese employed did not show any 

 effect, neither on the acid soil nor on that with calcium hydrate. 

 It seems that the immediate cause of infertility in the very acid soil 

 is not a calcium deficiency but the concentration of hydrogen-ions, 

 which can be reduced by lime and by potassium hydrate. 



Und series.— 3> grammes of lime did not suffice, after leaching 

 the soil, to reduce the acidity enough to ensure a normal develop 

 ment of the mustard. The soluble calcium salts (chloride and 

 sulfate) did not effect a noticeable change of the hydrogen ion con- 

 centration, neither in the soil nor in its water. Neither did they 

 help the growth, which was reduced by the chloride, i.e., by ex- 

 changing acid. 



Calcium hydrate and carbonate in smaller and larger quantities 

 enabled a satisfactory development of the mustard; this could not 

 be observed on the pots with potassium lye, especially on those 

 which received the small dose. When manuring with boron and 

 manganese an effect cannot be expected or noticed. In the series 

 1 and 2 one should observe the small content of Ca-ions in the 

 leaching water from the pots with well-developed plants. 



