Lbs. 



Lbs. 



Phosphorus. 



Potash 



27 



15 



6 



4 



THIRTY-SEVENTH ANNUAL CONVENTION. 117 



Lbs. 

 Amount and name of feed. Nitrogen. 



1,000 lbs. bran 25 



300 lbs. oil meal 20 



Total 45 33 19 



If the above feeds are purchased, we bring to the farm 45 

 pounds of nitrogen, 33 pounds of phosphorus and 19 pounds of 

 potash, and after we take out the fertility used in the making 

 of milk and make allowance for leeching and fermentation of 

 the manure, we can calculate that about one-half of the fertility 

 purchased in the bran and oil meal may be returned to the soil ; 

 or, roughly speaking, we would expect to return to the soil 

 about 17 pounds of the phosphorus out of the 1,000 pounds of 

 bran and 300 pounds of oil meal. Seventeen taken from forty- 

 three leaves 25, as the pounds of phosphorus that it is necessary 

 to purchase per cow to keep the land up to its original fertility. 

 It has been found by experiment that the best way to apply the 

 rock phosphate is to plow it under with -green material or mix 

 it with barn yard manure. Investigators have found that on 

 an average, a ton of manure is worth $2.00 and that if ten cents 

 worth of raw rock phosphate is mixed with it, it increases its 

 value to $3.00. 



It has been held by many that since dairying offers an op- 

 portunity for the rotation of crops, very little attention, if any, 

 need be given the soil to keep up its fertility. No one questions 

 that the rotation of crops is not beneficial to the soil; that it is 

 one of the necessary things in a successful system of agriculture, 

 but to state that rotation tends to increase the fertility is mis- 

 leading in the extreme, for the increased crop yields that come 

 by rotation should indicate that more fertility is being removed. 

 We cannot make something from nothing. The rotation of 

 crops puts the soil in better physical condition, it gives oppor- 

 tunity to grow crops which tend to liberate the fertility of the 

 soil. The single crop system encourages the growth of weeds 



