632 ANNUAL REPORT OF THE Off. Doc. 



phosphorus and 9 pounds of potassium, while 3 tons of clover Las 

 120 pounds of nitrogen, 15 pounds of phosphorus, and DO pounds of 

 potassium. Thus, it is seen that different crops remove different 

 amounts of fertility. By a chemical analysis one may find the 

 amount of these constituents in a soil, but to nnd their availability 

 is a different question. If, however, we find a soil lacking in one 

 or more of these elements we may reasonably expect to benefit il 

 by supplying some substance containing the lacking element. 



Here the subject of fertilizers comes in. These may be supplied 

 as commercial mixtures or as home grown material. Farm manure, 

 lime, ground bone, phosphate rock and potassium chloride are nat- 

 ural products and may be used to correct any deficiency in a soil. 

 The farm manure supplies some of all of the essential elements, 

 besides forming humus, which so materially aids in making the 

 plant food available. Lime corrects any acidity that may be pres 

 ent. Ground bone or phosphate rock supplies phosphorus, and po 

 tassium chlorid, potassium. These substances by the action of 

 humus and nitrifying bacteria soon become available as plant food. 

 Commercial fertilizers contain these substances in a soluble form, 

 thus making them more readily available, and also more liable to 

 loss. 



We have one species of plants, those belonging to the order 

 Leguminoseal, which act as hosts to a species of bacteria which 

 gather the nitrogen from the air and renders it available as plant 

 food. No other plants behave thus towards nitrogen. This makes 

 the clovers, alfalfa, soy beans, cow-peas, etc., especially valuable in 

 crop rotation. We have seen that different plants absorb different 

 amounts of the elements of plant food. Therefore, the farmer by 

 a judicious selection of crops is able to economize in plant food. It 

 is, therefore, potent that in any consideration of crop production 

 many points are to be considered. We have seen that the farmer 

 is often able to aid nature. In any rational sj^stem of farming 

 two main points should be kept in mind: (1) To get the most profit 

 out of the soil, and (2) to leave it in the best possible condition. To 

 leave it in the best possible condition one must take into considera- 

 tion all sides of the question. The best soil will be one in which all 

 of the essential elements of fertility are present, and in an available 

 condition as plant food, and one in which the physical properties 

 are of the best. Tillage should be excellent, humus and bacteria 

 should be there to perform their important function, and careful 

 and consistent cropping should be practical, the climatic conditions 

 regarding rainfall, humidity and temperature should be ideal. In 

 a soil with such conditions we may expect a good crop, and good 

 in every sense of the word. Thus we see that farming is quite a 

 business after all, and that the best farmer should be a laborer, a 

 nature student and, we may add, a good, practical business man. 



