150 



Appendix. 



tion the soil. I l)elieve it is usually more satisfactory to ask the soil questions 

 providing it can be done in an intelligent, systematic manner. The chemist may 

 analyze the soil carefully and tell to the thousandth part of one per cent just 

 how much nitrogen, phosphoric acid, potash and lime the soil contains, but he 

 cannot tell absolutely by present methods how much of this plant-food is available 

 for plant growth. Even though the chemist cannot determine accurately the avail- 

 able plant-food, still it is of much value and interest to know the total amount con- 

 tained in the soil. Analysis may show U.2u per cent, or approximately 7.000 

 pounds nitrogen (N) ; 0.30 per cent, or approximately 10,500 pounds phosphoric 

 acid (P2 Oo) ; 0.50 per cent, or approximately 17.500 pounds, total potash 

 (K20) in the surface foot per acre. Much of this plant-food may or may 

 not be available for a growing crop. 



If an old rusty safe, with doors locked, fell into the hands of a farmer and 

 if he knew that this safe contained .$10,000, it would be a great incentive 

 to try to unlock the safe and utilize the money. So also if a farmer has his 

 soil analyzed and finds that it contains ."lO.OOO to 40,000 pounds of plant-food 

 per acre, even if not available, tWs fact should be worth much to the farmer 

 because it should give him a strong incentive to try and farm in such a way as 

 to gradually make available for his crops this vast amount of plant-food 

 which is locked up in his soil. This plant-food in the soil is the farmer's 

 capital, or money just as much as the $10,000 in the old, rusty safe. 



A farmer can tell if his crops are due to a lack of available plant-food 

 by questioning the soil in the following manner : Suppose the farmer plans ti> 

 grow a cultivated crop in a ten-acre field. In the spring lay out several 

 experimental plats on a typical part of the field. Let each plat be one rod 

 wide and eight rods long, that is, one-twentieth of an acre. Apply the dif- 

 ferent plant-foods to these plats and study the effects. 



The simplest set of fertilizer experiments would be the following : 



8 Rods Long. 



1 rod wide. 



1 rod wide. 



1 rod wide. 



1 rod wide. 



1 rod wide. 



1 rod wide. 



15 pounds nitrate of soda. 



30 pounds acid phosphate. 



15 pounds muriate of potash. 



Blank ; no fertilizer. 



15 pounds nitrate of soda. 

 30 pounds acid phosphate. 

 15 pounds muriate of potash. 



1/2 ton barnyard manure. 



