STATE AGRICULTURAL SOCIETY. 123 



break them down. Since the cohesiveness of the soil depends so 

 greatly upon the quantity of water contained in it, it follows that 

 thorough draining, combined with deep tillage, whereby sooner or 

 later the stiffest clays become readily permeable to water, must 

 have the best effects in making such soils easy to work. 



The English practice of burning clays speedily accomplishes 

 the same purpose. When clay is burned and then crushed, the 

 particles no longer adhere tenaciously together on moistening, 

 and the mass does not acquire again the unctuous plasticity 

 peculiar to unburned clay. 



Mixing sand with clay, or incorporating vegetable matter with 

 it, serves to separate the particles from each other, and thus rem- 

 edies too great cohesiveness. 



When water freezes, its volume increases, as is well known. 

 The alternate freezing and thawing of the water which impreg- 

 nates the soil during the colder part of the year plays thus an 

 important part in overcoming its cohesion. The effect is mostly 

 apparent in the spring, immediately after " the frost leaves the 

 ground," but is usually not durable, the soil recovering its former 

 consistence by the operations of tillage. Fall-ploughing of stiff 

 soils has been recommended, in order to expose them to the 

 disintegrating effects of frost. 



IX. Absolute weight of soils. — According to Johnston, a cubic 



foot of dry silicious or calcareous sand weighs about 110 lbs. 



Half sand and half clay, 96 " 



Common arable land, 80 to 90 " 



Heavy clay, _. 75 " 



Garden mold, rich in vegetable matter, 70 " 



Peat soil, _ _ _ 30 to 50 " 



This concludes our study of the physical characters of the soil, 

 as they affect its fertility. It is seen that our knowledge is very 

 incomplete, and the whole subject is in the highest degree worthy 

 of an extended investigation. Such a reseach is an enter])rise 

 not at all difficult to carry out, by a proper condonation of know- 

 ledge, skill and pecuniary means. I am more and more convin- 

 ced that no one thing .would so greatly contribute to increase and 

 maintain the productiveness of our fields, as a thorough knowledge 

 and application of the principles that are stated or suggested in 

 the previous pages. We shcnild thereby secure the proper basis 



