REVIEW QUESTIONS 339 



crops require different cultivation? 345. How can the best kind of 

 cultivation for a crop be determined? 346. How can soils best be 

 cultivated to prevent washing and gullying? 347. What treatment 

 should such soils receive to be permanently improved? 348. What 

 relationship exists between bacterial diseases of soils and of crops ? 

 349. What treatment should soils receive to prevent bacterial 

 diseases? 350. How can the spreading of bacterial diseases 

 through infected seed be prevented? 351. Why must the sanitary 

 condition of a soil be considered? 352. What are the effects of some 

 forms of fungi upon soils? 353. In what way does thick or thin 

 seeding affect plant growth? 354. What effect does abnormal 

 crowding of plants have upon growth ? 355. How would you deter- 

 mine the amount of seed for crop production? 356. How would 

 you determine the most suitable crop for any soil ? 357. What should 

 be the aim in selecting crops for soils? 358. Why should the crop 

 selected vary with different types of soil? 359. What is the in- 

 herent fertility of soils? 360. What is the cumulative fertility of 

 soils? 361. How can the total fertility of soils be best increased? 

 362. Describe soils of the highest fertility. 363. Why must the 

 amount of plant food as well as the physical condition of the soil be 

 considered in the improvement of soils? 364. What relation does 

 the fertility of the soil bear to any agricultural system ? 



