ELEVENTH ANNUAL YEAR BOOK— PART VIII 413 



Dr. Hopkins says that there is enough potash in the soil to last for 

 many years and at the present time we need give it no consideration. In 

 our calculation of the amount of fertility used, it will be noted that there 

 are 43 pounds of phosphorus lost which can be obtained in the form of 

 raw rock phosphate for the sum of 4 cents per pound or making the 

 43 pounds worth $1.72 the cost of fertility that should be purchased for 

 every cow kept in the herd. This calculation may be a little high for the 

 average cow, but it comes very cose to what Dr. Hopkins advocates in re- 

 taining and building a permanent system of agriculture. He states that 

 a farmer who is raising maximum yields of corn, clover, oats and wheat 

 should apply 250 pounds of the raw rock phosphate annually, or 1,000 

 pounds every four years. If we calculate that the raw rock phosphate fur- 

 nishes phosphorus at 4 cents a pound, this amounts to $1.25 per year per 

 acre. It should be remembered that in my calculation, assuming that the 

 cow consumed a certain amount of feed, it would require $1.72 worth of 

 phosphorus which is not very far from the figures advocated by Dr. 

 Hopkins and based upon actual field tests. I feel, therefore, reasonably 

 safe in stating that every dairyman should make it a point to purchase 

 from $1.00 to $1.50 worth of raw rock phosphate for each cow that he 

 keeps in order to keep his soil up and supply plant food for the produc- 

 tion of maximum yields of crops. 



I realize that many of the farmers in this community, purchase a con- 

 siderable portion of their feed; in view of this it is not necessary to pur- 

 chase nearly as much of the rock phosphate as where no feed is brought 

 to the farm. In the following table is shown the amount of fertility con- 

 tained in 1,000 pounds of bran and 300 pounds oil meal. 



Lbs. Lbs. Lbs. 



Amount and Name of Feed Nitrogen Phosphorus Potash 



1 JMIO pounds bran ' 25 27 15 



300 pounds oil meal 20 6 4 



Total 45 33 19 



If the above feeds are purchased, we bring to the farm 45 pounds of nitro- 

 gen, 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 re- 

 turned 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 

 twenty-five, 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. Investi- 

 gators have found that on the 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. 



