2^9 



do not know, by illustration. The egg is the simplest of all 

 animal forms of matter. The white of the egg consists of water 

 and albumen, and any albumen contains about 16 per cent, of 

 nitrogen. Good lean meat, beef, mutton or pork, contains, 

 when free from from fat, about 75 per cent, of water and 25 per 

 cent, of substance, which, like albumen, contains 16 per cent, of 

 nitrogen. Bones likewise contain about 30 per cent, of gluten, 

 which has about 16 per cent, of nitrogen, while they also con- 

 tain phosphate of lime to the extent of about 60 per cent. Flesh 

 and blood likewise contain potash, and milk contains all these 

 substances. Animals cannot get along without bones, so phos- 

 phate of lime is essential to the animal. The animal must take 

 this substance entirely from its vegetable food, so it becomes 

 to this extent, if to no other, essential to the plant. All these 

 substances then, chemistry teaches, must exist in the ^oil, and 

 the farmer must put them into condition to be readily obtained 

 by plants if he would secure good crops. 



How much of each should a good soil contain? 



A standard authority declares that a good soil should con- 

 tain 90,000 pounds of potash in a layer of one foot deep, cover- 

 ing one acre, and that in the same space a poor soil should con- 

 tain 40,000 pounds. So, too, a good soil may contain 15,000 

 pounds of phosphoric acid in form of phosphate of lime. The 

 nitrogen of the soil varies largely, but may even exceed in quan- 

 tity the other substances named. 



These substances seem enormous when we consider how 

 much may be removed from an acre, by each of our leading 

 crops, say corn, oats or wheat. Corn, which is the most exacting, 

 removes each year per acre, N. 60 lbs., K 3 O.56 lbs., P 3 O5.30 

 lbs.; oats removes N. 30 lbs., K 3 O.30 lbs., P 3 O5.12 lbs.; 

 wheat, N. 51 lbs., K 3 O27.3 lbs., P 3 O5.21 lbs. Why, then, 

 should the soil become exhausted? Because these substances 

 occur in the soil in conditions in which they cannot be taken and 

 utilized by plants. Straw or wood contains nitrogen, which 

 ultimately may serve for plant food, but first the straw or wood 

 must rot and decay, in order that the nitrogen ma,y be changed 



