PROBLEM OF CROP PRODUCTION 367 



the farmer has to solve, let us examine the nature and 

 effectiveness of the instruments he has 'been given with 

 which to achieve his purpose. 



328. The Means at Man's Disposal for Controlling or In- 

 fluencing the Factors of Growth, Profit and Permanence. 



The instruments now available for controlling or in- 

 fluencing the factors of growth, profit and permanence 

 are: 



1. The choice of suitable crops. 



2. Suitable crop management practices. 



3. The improvement of crops by selection and breeding. 



4. Irrigation or drainage, or both. 



5. Tillage. 



6. Suitable crop rotations. 



7. The use of live stock. 



8. The application of business principles to the man- 

 agement of the whole farm the land, the stock, the 

 labor, the finances and the machinery and other 

 equipment. 



9. The use of legumes and nitrogen fixing bacteria. 



10. The utilization of manures. 



329. The Choice of Suitable Crops. Nature has given 

 us some plants that resist disease, some that resist frost, 

 some that resist drought, and some that avoid these con- 

 ditions. A great number of crops suited to different 

 systems of farming are available to choose from, and the 

 experience of farmers and the records of our experiment 

 stations are fast teaching us the ones that are best suited 

 to our climate and' soil. The value of some new and un- 

 tried crops has yet to be determined, and the suitability 

 of different classes and types of crops for peculiar local 

 soil and climatic conditions is a line of work that needs 

 greater attention. But our present knowledge, if utilized, 



