THE RELATION OF LIME AND MAGNESIA TO PLANT 
GROWTH. 
I. LIMING OF SOILS FROM A PHYSIOLOGICAL STANDPOINT. 
By Oscar Loew, 
Expert in Physiological Chemistry. 
INTRODUCTION. 
The beneficial effect of slaked lime and gypsum in crop production 
has been known since the early ages. The old Romans as well as the 
Japanese and Chinese were well acquainted with the practice of liming. 
The effects, however, were not uniform either on different soils or for 
different crops, and damage was sometimes incurred by overliming. 
It is a question of great importance to the farmer to be able to ascer- 
tain when his soil needs liming, and how much of the lime or lime 
compounds to apply: also whether slaked lime, carbonate of lime, or 
sulphate of lime is the most suitable form, and whether magnesian 
limestone must be excluded. The quantities of lime required vary, 
according to circumstances and the nature of the crop, from 500 to 
6,000 pounds per acre. Boggy and clay lands require more lime than 
other soils. It is preferable to add moderate quantities at compara- 
tively short intervals (every three to six years) rather than a very 
large quantity at once. Heavy soils may be made more porous by the 
use of slaked lime, and fine sandy soils may gain in firmness, while 
soils with an acid reaction may become profitably neutralized. 
The decomposition of humus in soils is hastened by lime, its nitro- 
gen being liberated as ammonia and becoming available to the plant 
either as ammonia or as nitrates after nitrification. The process of 
nitrification is also promoted by the presence of lime. On sour, boggy 
lands marsh plants can easily be replaced by forage plants after an 
application of lime. Liming algo has great importance in connection 
with the raising of live stock, since the formation of bone is imperfect 
where their food is too poor in lime. Again, certain parasitic fungi 
and insects in the soil are easily killed by the alkaline properties of 
burnt lime. Lime and gypsum can also in certain cases release such 
potash in the soil as is still unavailable. This, as well as the enhanced 
root hair production under the influence of the increased amount of 
lime, accounts for the greater absorption of potash by the plant on 
soils rich in lime. 
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