CHAPTER IV 

 CROPS 



The so-called crop plants — those plants which are of 

 value to the farmer — owe their importance to certain of 

 their constituents. For example, the grains are valuable for 

 the starch, fixed oils, and proteins, which they contain; 

 potatoes for their starch; nuts for their oils; peas and beans 

 for their proteins; and beets for their sugar. Since most of 

 the ordinary crop plants are raised almost entirely as food 

 for stock or for man, it is of interest to know something of 

 the amounts, not only of the valuable, but also of the useless 

 food constituents in the various crops. 



The determination of the different individual plant com- 

 pounds discussed in Chapter III involves considerable 

 difficulty, and although many of the determinations can be 

 made with accuracy, the time consumed is very great even 

 if only a partial analysis is made. For scientific stock 

 feeding it is only necessary to know the amount of all the 

 carbohydrates that are reasonably digestible; the amount 

 of those carbohydrates which are indigestible; the amount 

 of total protein material; of total oil; and of total mineral 

 matter. Consequently there is employed a method which 

 serves to differentiate the classes of constituents rather 

 than the compounds in each class. 



The determinations are more or less conventional and in 

 some cases only approximate, but on the whole they are 

 reasonably accurate. This general method of analysis is 

 known as the u YVeende Method" since it was the method 

 employed at the Weende Experiment Station, Germany, 

 by Dr. W. Henneberg, and reported by him in 1864. With 

 some modifications it is still in use. A very brief description 

 of the following determinations will help to make clear the 

 meaning of terms which are referred to very frequently in 

 any discussion of foods. 



