158 



REPORT OF THE COMMISSIONER OF AGRICULTURE. 



with the necessary moisture. The soil, however, must be permeable 

 enough to let the excess of water drain away; water-logged soils show 

 immediate improvement when properly drained. 



THE BARRENNESS OF SOIL,. 



JTo soil is absolutely barren, unless it contains substancv.^s poisonous 

 to plants, such as an excess of organic acids, alkaline salts, the sulphate 

 (iT irou, or the sulphide of iron or other injurious ingretlients ; but it 

 may be so considered when it will not produce such crops as the farmer 

 iu;i\ wish to raise. Such a soil may, in many cases, be made produc- 

 iive by adding to it the constituent of which it is in need; but, if tliis 

 cannot be done except at a prohibitory cost, or one at which more fer- 

 tile ground can be procured, the soil may be regarded as practically 

 worthless. 



THE AVERAGE COMPOSITION OF ORDINARY FARM CROPS. 



The amount of food taken from the soil by diflerent crops is given in 

 the following table taken from " The Chemistry of the Farm," pp. 38, 39. 

 This table gives the average composition of ordinary farm croj^s, as 

 grown in England, and the composition of the produce of beech, spruce 

 fir, and Scotch pine forests felled for timber, and are the result of exten- 

 sive investigations made in Bavaria. 



The quantities of carbon, hydrogen, and oxygen present are omitted ; 

 also some of the smaller ash constituents. By '^pure ash" is meant the 

 ash minus sand, charcoal, and carbonic acid. 



Table I. — The tceight and average composition of ordinary crops, in pounds, per acre {R. 



Warington). 



*A ton of 2,240 pounds. 



