THE USES OF LIME IN AGRICULTURE AND HORTICULTURE, 24I 
of the air, and the Nodule Bacterium, which has the same power, but 
works in conjunction with the host plant in the nodules so familiar 
on the roots of Leguminosae. All plants of this important Family 
are therefore, with a few exceptions (e.g. lupines, seradella, and 
gorse), greatly dependent on a supply of lime in the soil. All the 
beneficial bacteria can work only when the soil is neutral or slightly 
alkaline ; as soon as the soil becomes acid, bacterial action is suspended 
and moulds and microfungi take their places. Lime is the cheapest 
and most suitable alkali we can use to maintain this neutrality. 
The foregoing facts abundantly prove that no cultivator of the 
soil can afford to ignore the important and economical improvements 
that can be effected by the application of lime. It has been already 
shown how the texture of a soil may be changed by its use, and it is 
also true that a startling improvement may at the same time be 
effected in the character of the vegetation. The best instance of this 
is the effect of liming sour and coarse pastures, on which it will give 
rise to the fine grasses and clovers eagerly sought after by stock, in 
place of bents and other rough grasses traditionally known to be of 
small feeding value and distasteful to all stock. Given then that it 
is imperative for every cultivator to ascertain whether his soil is 
lacking in lime, the next point is that he should know how to obtain 
the information. 
In the first place, much may be learnt by a careful examination 
of the plants and weeds naturally supported by the soil. On arable 
land sheep-sorrel, corn marigold, and spurrey are almost certain 
indications of a deficiency of lime ; in waste places the growth of 
foxglove and bracken are significant of the same need, and in pastures 
an absence of leguminous plants is the surest guide. The greatest 
deficiency is found in peaty soils and old permanent pastures, and on 
very heavy and very light soils. In the case of such heavy soils a 
black acid peat will accumulate, particularly if the lack of lime is 
accompanied, as is frequently the case, by waterlogging. Iron pans 
composed of oxide of iron will form below the surface, and the soil 
water will contain soluble iron salts, whose presence is indicated by 
a characteristic iridescent scum that forms on the water in the ditches. 
Fungus diseases will also be prevalent. In the case of light soils, a 
black humus will accumulate, the lack of leguminous plants will be 
very noticeable, and such diseases as finger-and-toe will be rampant. 
In any soil the complete absence of lime produces something approach- 
ing sterility, i.e. starvation of plant life. Beyond these general 
indications one of the simplest tests is that of introducing litmus 
paper to a strong solution of the soil : if it is markedly acid, blue 
litmus will be changed to pink ; if decidedly alkaline, pink litmus 
becomes blue. Another simple and very useful test is that afforded 
by the addition to the soil of a little hydrochloric acid (spirits of salts), 
when the presence of lime will cause effervescence.* 
* See " Economy in the Garden," published by the Society, paragraph 15, 
p. 8. 
VOL. XUI. R 
