312 SOILS 



does impoverish farm soils of available plant food, 

 reducing their value for cropping, temporarily 

 at least. This plant food is being shipped off in 

 butter, eggs, hay, corn, apples, wheat, cotton, 

 potatoes, and in every other crop that goes to 

 market. The fertility that goes off in crops never 

 returns to that land. But some crops, or part of 

 them, stay on the farm. These are the crops that 

 are fed to stock and the manure returned to the 

 land. 



A Bank Account with the Soil. In reality, 

 when we sell crops we are selling the fertility of the 

 soil, not only the nitrogen, potash and phosphoric 

 acid the crops have used, but also a certain 

 amount of good texture or "condition" which is 

 lost by the growth of the crop. A farmer should 

 know the relation between the price received for 

 his crop and the amount of plant food contained 

 in it. 



The amount of fertility lost to the farm by the 

 sale of different crops varies greatly. The loss in 

 grass and cereal crops is much greater than in 

 vegetable and fruit crops. If a ton of wheat, which 

 contains 38 Ibs. of nitrogen, 19 Ibs. of phosphoric 

 acid and 13 Ibs. of potash, sells for 60 cents a bushel, 

 the nitrogen in it sells for 41 cents a lb., and the 

 phosphoric acid and potash for 14 cents a lb. If 

 a ton of milk, which contains 12 Ibs, of nitrogen, 

 4| Ibs. of potash and 3^ Ibs. of phosphoric 

 acid, is sold for $30, the nitrogen in it brings 

 $2 per lb., and the phosphoric acid and 

 potash about 70 cents per lb. If, however, 

 cream or butter is sold and the skim milk 

 fed to hogs, calves or chickens, most of the 

 plant food is recovered in the manure of these 

 animals. 



