23 Gisiger: Deficiencies Caused by Excesses 



and by its hydrolysis an alkaline reaction results according to the 

 equation: 



Ca(HCOs)2 + 2HjO = CaCOH)2 + 2H2CO3. 



If calcium bicarbonate could be washed out, it would be possible to 

 reduce the injury to growth, but there would remain the well- 

 saturated absorbent complex, which can also give rise to an un- 

 favourable and high concentration of hydroxide (OH)-ions. 



To prove the effect of leaching, the following experiment was 

 made. An acid pasture soil was limed with increasing quantities 



Table 1 : Leaching of differently limed soils: — 



Leached CaO 



in 3 parallel series. After liming the first and the third series 

 were immediately planted and the third series received in addition 

 to the general base manure of P N K, a further 31 mg of boric 

 acid. Mustard was chosen as a test plant. The middle series 

 was leached during a period of two months before planting. For 

 this leaching, water was poured daily on the pots, so that from 

 75 to 100 cm^, dripped through, i.e., in two months a total quan- 

 tity of 5500 cm^ of water. 



95 to 98% of the added lime remained in the soil; neverthe- 

 less, in the test remarkable differences in growth were observed 

 between the leached and the unleached series without boron. 

 The injurious effect of the higher lime dressings is particularly 

 interesting. In the unleached series the plants in the pot with 

 the 5th lime quantity are restricted in growth, in the pots with 

 the next higher lime quantity the growth of the plants was almost 



