]^]^g BOARD OF AGRICULTURE. 



imbibing and fixing all the ammonia, potash and phosphoric 

 acid that are brought into it in any way. The particles of 

 earth thus minutely divided, retain in a proper state the 

 water which performs so important ofiices in the vegetable 

 economy. By plowing in the stubble and roots of harvested 

 crops, the fertility of the fields is greatly promoted. In an 

 old pasture or meadow field, when plow^ed up, the turf com- 

 posed of what is left after cropping, living roots and so forth 

 in the soil, is equal to four times the weight of that j^ear's hay 

 crop. If a ton and a half of hay had been taken oft', then 

 there are six tons of dry or vegetable matter which remain in 

 the soil. In the case of clover, at the end of the second year 

 the quantity of dry vegetable matter left in the form of roots 

 is equal to one-half of the whole hay which the clover has 

 yielded in the two years. 



Among the mechanical methods of improving the soil in 

 the old countries where more capital can be employed, in 

 agricultural work, drainage stands pre-eminent. This in 

 England marks the advance of agriculture, and is practiced 

 extensively on uplands as well on lower tracts. By a judicious 

 system of underdrainage, many soils naturally cold, heavy 

 and unproductive, have been made warm, porous and fertile. 

 The harmful staa-nant water with which the soil was clogged 

 has been removed. The air is enabled to circulate freely, 

 supplying oxygen, carbonic gas and perhaps nitrogen, to be 

 chemically combined in the interspaces of the soil with sub- 

 stances that by this contact are changed to soluble plant food. 

 The evaporation of water from the surface is prevented, 

 and the soil receives the genial warmth. Water cannot be 

 heated, from the top, and earth whose pores are filled with 

 moisture must remain cold. By drainage the season is pro- 

 longed, and certain crops are made possible, that could not 

 otherwise be raised in this latitude. 



To keep up the fertility of the soil there must be a liberal 

 supplj^ of manure judiciously applied. With all the advan- 

 tages of mechanical culture and of the rotation of crops, and 

 W'hatever mi^ht be sained in the ruder method of letting the 



