368 HOW THE NEEDS OF SOILS MAY BE DETERMINED 



FARM EXAMINATIONS 



Farm Visits Are Essential. Whenever a farmer wishes definite 

 information concerning the needs of his soil, drainage, crop rota- 

 tion, etc., it is most satisfactory, if such provision is made, for a 

 representative to visit the farm. In this way a soil fertility expert 

 is able to consider all conditions, note the character of the subsoil, 

 observe the growing crops if circumstances permit, obtain the 

 cropping history of each field if necessary, and if he thinks it 

 important, take samples of soil for chemical analyses. The 

 farmer should receive a report with recommendations for soil 

 improvement. When several farmers in a community become 

 interested in such farm examinations it is often advisable to 

 " follow up" or reinforce such work with field demonstrations. 



Field demonstrations may be conducted as home projects to determine 

 the values of each of the methods of soil improvement which are considered 

 profitable. These may include projects in liming, inoculation, green- manuring, 

 use of barnyard manure, use of commercial fertilizers, drainage, irrigation, 

 subsoiling, dry farming methods, mulching, etc. In each trial check plots 

 should be left for contrast. This will make the trials more conclusive. 



Consult chapters XII and XIII. 



QUESTIONS 



1. Can the fertilizer needs of a soil or its cropping possibilities be determined 



by chemical analysis? Explain. 



2. What other methods have been devised to answer these questions? 



3. Name and discuss the conditions which should be considered before 



deciding upon chemical analysis for the solution of a soil fertility problem. 



4. State specifically how organic matter in soils affects the fertility factors. 



5. Why were methods of chemical analysis devised to determine the availa- 



bility of the elements? What success has been attained? 



6. In general, mention some benefits to be derived in determining the total 



amount of each of the important elements contained in soils. 



7. For practical purposes, what analyses are commonly made? Discuss the 



value of each determination. 



8. Discuss the results secured in pot tests in relation to practical operations 



of the farm. 



9. How are pot tests usually made? 



10. What is the best method whereby the fertilizer needs of soils may be 



determined and principles governing fertility maintenance established? 



11. How do experiment stations conduct such tests? 



12. Explain how farmers can conduct simple lime and fertilizer tests. 



13. Mention some points to be observed in making these tests. 



14. Discuss the advantages in having the soils examined on the farm by a 



soil fertility expert. 



