INTENSWE FAEMING. 121 



layers. The tendency of the nitric acid to withdraw from 

 that portion of the cultivated soil, upon which most of our 

 farm-crops feed, renders it quite natural that its efficiency as 

 a plant-feeder can be secured in an economical way, only by 

 a continual production, equal to the demand. As decaying 

 animal and vegetable organic substances furnish consequently 

 either ammonia or nitric acid, they are in a superior degree 

 qualified to supply the nitrogen plant-food for our crops, pro- 

 vided they are present in a sufficient quantity, aAd in a 

 suitable form of disintegration. 



In their advanced state of decay as humus, they contain 

 still, from 2 to 4 per cent, of nitrogen. 



It is therefore considered most essential for every kind of 

 soil under cultivation, to contain at all times a certain per- 

 centage of it. 



Uncultivated lands, as a general rule, are more or less des- 

 titute of it, for a scanty growth reduces its amount, directly 

 and indirectly. 



From the preceding remarks regarding the character and 

 the extent of the various natural nitrogen resources of the 

 soil, it must be apparent that they cannot and ought not to 

 be relied on, when aimius; at reminicrative farmins:. 



Intensive farming does not mean to tax the natural strength 

 of the soil to its utmost limit, but to increase the store of its 

 movable or convertible plant-food by rational and economical 

 means to the highest possible amount ; the larger the export 

 and the import of plant-food, the more intensive is the system 

 of cultivation. 



It is of particular importance, to provide for the young 

 plant in its earliest state of growth a sufficient amount of 

 active nitrogen compounds, for its presence is essential for the 

 formation of cells ; it stimulates the growth of leaves and roots, 

 and places thereby the young plant in the most advantageous 

 condition to take hold of the resources of both air and soil. 



To restore to our more or less exhausted lauds at the proper 

 time, and in a suitable form, the various articles of plant-food, 

 which the latest crop has abstracted, does not entitle to the 

 highest expectation . * 



* The following tables show the amount of nitrogen, potassa and phosphoric 

 acid contained in an air-diy average crop per acre of Massachusetts, according to 

 16 



