174 



Agricultural Chemistry. 



b. Fruit of annual plants such as melons, pumpkin. 



squash and tomato. 

 V. Forest growth including, 



hardwooded and softwooded perennial plants. 

 V I . Miscellaneous crops including, 



tobacco, and the onion, cabbage, and other truck crops. 



In considering the seed crops we must take into account the 

 straw as well as the grain. The former portion of these crops 

 is not important in all cases as a feeding material, but it always 

 stands responsible for a part of the exhaustion of plant food 

 from the soil. For this reason the tops as well as the roots of 

 root-crops should be considered. 



The yield of crops, both in the total substance produced and 

 in its proportion of plant compounds, varies widely. These fac- 

 tors control to a large extent the value of the crops as feeding- 

 stuffs, and their demands upon the plant food constituents of 

 the soil. A rational comparison of the composition of crops can 

 be made only upon the basis of yield of dry matter and of the 

 individual nutrient compounds or groups of compounds con- 

 tained therein, per acre. The following table gives the total 



Yield in Pounds Per Acre. 



