40 CROPPING SYSTEMS 



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QUESTIONS 



1. How does rock become productive soil? 



2. Where did the organic matter come from ? 



3. How did soils acquire their nitrogen supply? 



4. Why are legumes so important? 



5. Why is organic matter so important ? 



6. What appear to be the direct effects of continuous cropping on a 



productive soil? 



7. Can deterioration be avoided? 



8. Explain what is meant by single cropping; alternate cropping; and 



rotation cropping. 



9. Name some good rotations. 



10. What factors in productivity does rotation maintain? 



11. What does rotation fail to maintain? 



12. State in brief results obtained at Ohio Experiment Station. 



13. What is a "complete" fertilizer? 



14. Does the chemical composition of a crop indicate the kind of fertilizer 

 i to apply? 



15. Give composition of typical fertilizer mixtures. 



16. What are the three forms of agricultural lime and how do they differ? 



17. Which crops respond best to fertilizer and which to manure? 



18. How is the value of manure made by one animal determined? 



19. How much of the plant food is recovered in the manure? 



