SOILS. 



In the solution of all problems relating to fertility and pro- 

 duction we have some important laws or rules that have been 

 established by scientific agriculture : 



1. A soil is fertile when it contains all available plant foods neces- 

 sary for the nutrition and growth of plants. 



2. Crops remove a part of the soil's fertility. 



3. Fertility is renewed by natural and artificial agencies. 



4. Fertility of soil remains unchanged if all elements contained 

 in the crop are returned to the soil. 



5. The law of the minimum established by Leibig, is that a plant 

 will develop and grow only in proportion to the essential 

 element most feebly represented. 



6. When we sell grain, hay, live stock, milk and fruit, we are 

 removing certain constituents that must be replaced by some 

 natural or artificial methods. 



7. Various kinds of crops differ as to the amount of sunlight, 

 heat, moisture, and plant foods that are necessary for a max- 

 imum crop. 



PROBLEM. 



1. If weather conditions are favorable for the growth of a crop 

 of 100 bushels of corn per acre, and there is only phosphoric acid 

 enough available to produce 70 bushels, and only enough nitrogen avail- 

 able to produce 40 bushels; what will be the yield per acre? 



Natural Fertilizers. 



The following table gives the fertilizer constituents in 1,000 

 pounds of feed stuffs, and is taken from Henry's "Feeds and 

 Feeding" : 



Nitrogen 

 Name of Feed. in 



Pounds. 



Corn 18.2 



Corn and cob meal .' . . 14.1 



Oats (grain) ' 20.6 



Wheat (grain) 23.6 



Wheat bran 26.7 



Wheat middlings 26.3 



Cotton seed 31.3 



Cotton-seed meal 67 . 9 



Linseed meal (new process) 57.8 



Corn silage 2.8 



Corn stover . 10.4 



