I38 MAINE AGRICULTURAL EXPERIMENT STATION. I904. 



able form. Moreover different plants have different feeding 

 capacities, so that the plant food which would be available to 

 one class of plants might not to another. This question can be 

 best answered by putting it directly to the soil in a so-called soil 

 test experiment.f 



If a farmer has not experimented with his soil so that he 

 knows to what fertilizing elements it most readily and profitably 

 responds, he must be guided in the purchase of plant food by 

 general principles. And this is as true in the purchase of mixed 

 as unmixed goods. In either case there is considerable uncer- 

 tainty. The purchase of unmixed goods, however, has the 

 advantage that the farmer knows what he has used, and if he is 

 observant and keeps record of his management, he will know 

 where he made the mistake and how to avoid it the next season. 



In addition to the plant food in the soil, the farmer has at his 

 disposal the manure from the farm animals and a very consider- 

 able amount in that left in roots and stubble from the preced- 

 ing crop. A few figures illustrative of this are given in the table 

 which follows. 



AMOUNT OE NITROGEN, PHOSPHORIC ACID AND POTASH LEET IN 

 THE ROOTS (TO THE DEPTH OE 6 INCHES) AND STUBBLE IN ONE 

 ACRE AFTER THE CROP HAS BEEN REMOVED AND A NEW GROWTH 

 HAS STARTED, AND IN FARM MANURE. 



Kind of Plants. 



Nitrogen, 

 pounds. 



Phosphoric 



acid, 



pounds. 



Potash, 

 pounds. 



Timothy and red top, average of 2 experi- 



02 

 36 

 10 



15 

 10 

 10 



31 





22 





8 









♦Manure is extremely variable in composition and weight. A cord of manure 

 will weigh from 3 to 4 tons. Farmers' Bulletin 192, of the TJ. S. Department of 

 Agriculture, on farm manures, can be had free from your Congressman, or the 

 Secretary of Agriculture. Washington, D. C. 



t Circular No. 8 of the Office of Experiment Stations of the United States Depart- 

 ment of Agriculture explains how such a test can be made. A postal card sent to 

 the Secretary of Agriculture, Washington or to your Congressman will bring tflis 

 circular free. 



