STATE AGRICULTURAL SOCIETY. 109 



millions pounds of water. This water comes from the soil and 

 passes through the plant. All the mineral matters and a portion 

 of the organic bodies, which feed the plant, are carried into it by 

 this water. So long as evaporation goes on from the surface of 

 the soil, so long there is a constant upward flow of saline matters. 

 Those portions which do not enter vegetation accumulate on or 

 near the surface of the ground; when a rain falls they are washed 

 down again to a certain depth, and thus are kept constantly 

 changing their place with the water which is the vehicle of their 

 distribution. In regions where rain falls periodically or not at 

 all, this upward flow of the soil water, often causes an accumu- 

 lation of salts on the surface of the ground. Thus in Bengal, 

 many soils which in the wet season produce the most luxuriant 

 crops, during the rainless portion of the year become covered 

 with white crusts of saltpeter. Doubtless the beds of nitrate of 

 soda that are found in Peru have accumulated in the same man- 

 ner. So in our western caves, the earth sheltered from rains, is 

 saturated with salts — epsom salts, glauber salts and saltpeter or 

 mixtures of these. Often the rich soil of gardens is slightly 

 incrusted in this manner in our summer weather; but the saline 

 matters are carried into the soil with the next rain. 



It is easy to see how, in a good soil, capillarity thus acts in 

 keeping the roots of plants constantly immersed in a stream of 

 water or moisture that is now ascending, now descending, but 

 never at rest, and how the food of the plant is thus made to cir- 

 culate around the organs fitted for absorbing it. 



The same causes that maintain this perpetual supply of water 

 and food to the jtlant, are also tflicacious in constantly preparing 

 new supplies of food. The materials of the soil are always 

 undergoing decomposition, whereby the silica, lime, phosphoric 

 acid, potash, &c., of the insoluble fragments of rock, become 

 soluble in water and accessible to the plant. Water charp:ed with 

 carlxmic acid and oxygen, is the chief agent in these chemical 

 changes. The nK)re extensive and rapid the circulation of water 

 in the soil, the more matters will be rendered soluble in a given 

 time, and other thinc^s being equal, the less will the soil be 

 dependent on manures, to keep uj) its fertility. 



No matter how favorable tlie structure of the soil may be to 

 the circulation of water in it, no continuous U])ward movement 



