182 THE YEAR-BOOK OF AGRICULTURE. 



tion, or the property which most liquids have to rise in tubes, or between plane and curved 

 surfaces. 



The minute interstices between the particles composing the soil are, to all intents and pur- 

 poses, small tubes, and act as such in elevating moisture from below to the surface. The 

 particles held in solution by the water are likewise elevated with it, and are left, on the eva- 

 poration of the water, distributed throughout the surface soil. This explains the reason why 

 manures, when applied for a short or longer time upon the surface of soils, 'penetrate to so 

 slight a depth. Every agriculturist is acquainted with the fact that the soil directly under 

 his barn -yard, two feet below the surface, (that is, any soil of any ordinary fineness,) is quite 

 as poor as that covered with boards or otherwise, two feet below the surface, in his meadow ; 

 the former having been for years directly under a manure-heap, while the latter, perhaps, 

 has never had barn-yard manure within many rods of it. The former has really Wn sending 

 its soluble materials to the surface soil, the latter to the surface soil and the vegetation 

 grown near, or upon it, if uncovered. 



The capillary attraction must vary very much in different soils ; that is, some have the 

 power of elevating soluble materials to the surface from much deeper sources than others. 

 The pores or interstices in the soil correspond to capillary tubes. The less the diameter of 

 the pores or tubes, the higher the materials are elevated ; hence, one very important con- 

 sideration to the agriculturist, when he wishes nature to aid him in keeping his soil fertile, 

 is to secure soil in a fine state of mechanical division and of a high retentive nature. Nothing 

 is more common than to see certain soils retain their fertility with the annual addition of 

 much less manure than certain others. In fact, a given quantity of manure on the former 

 will seem to maintain their fertility for several years ; while a similar addition to the latter 

 quite loses its good effects in a single season. The former soils have invariably the rocks, 

 minerals, &c. which compose them in a fine state of division; while the latter have their 

 particles more or less sandy and coarse. S. M. SALISBURY, M.D., in Prairie Farmer. 



Benefit of Droughts. 



IT may be a consolation to those who have felt the influence of long and protracted dry 

 weather, to know that droughts are one of the natural causes to restore the constituents of 

 crops and renovate cultivated soils. The diminution of the mineral matter of cultivated 

 soils takes place from two causes : 



1. The quantity of mineral matter carried off in crops, and not returned to the soil in 

 manure. 



2. The mineral matter carried off by rain water to the sea by means of fresh- water streams. 

 These two causes, always in operation, and counteracted by nothing, would in time render 



the earth a barren waste, in which no verdure would quicken and no solitary plant take 

 root. A rational system of agriculture would obliterate the first cause of sterility, by always 

 restoring to the soil an equivalent for that which is taken off by the crops ; but as this is 

 not done in all cases, Providence has provided a way of its own to counteract the thriftless- 

 ness of man, by instituting droughts at proper periods, to bring up from the deep parts of 

 the earth food on which plants might feed when rains should again fall. The manner in 

 which droughts exercise their beneficial influence is as follows : During dry weather, a con- 

 tinual evaporation of water takes place from the surface of the earth, which is not supplied 

 by any from the clouds. The evaporation from the surface creates a vacuum, (so far as the 

 water is concerned,) which is at once filled by the water rising up from the subsoil of the 

 land ; the water from the subsoil is replaced from the next below, and in this manner the 

 circulation of water in the earth is the reverse to that which takes place in wet weather. 

 This progress to the surface of the water in the earth manifests itself strikingly in the dry- 

 ing up of springs and of rivers and streams which are supported by springs. It is not, 

 however, only the water which is brought to the surface of the earth, but also all that which 

 the water holds in solution. These substances are salts of lime, and magnesia of potash and 

 soda, and, indeed, whatever the subsoil or deep strata of the earth may contain. The water, 

 on reaching the surface of the soil, is evaporated, and leaves behind the mineral salts, which 



