564 



cultivation may be made to simulate the effects of a favorable climate, 

 so that in general we are justified in the conCltisiori tMt-'^thile unculti- 

 vated plants and their fruits are wholly'd't^ii^n'cWn^'dn the weather, 

 yet methods will be found by which we ma}" r^td'^r the harvests from 

 cultivated j^lants largely independent of the weather. 



(7) The data here collected demonstrate that the richness of the 

 soil determines the amount of the annual cereal crop more than does 

 the climate. The latter determines principally the dates of sowing, 

 ripening, and the immunity from early or late frosts or the possi- 

 bility of bringing the plant to maturity. 



(8) We see that rain or irrigation water, so necessary as the 

 medium for bringing the nitrogenous molecules from the soil up 

 into the seed cells of the plant, also by drainage and seepage carries 

 away any such molecules if these are present as earths or manures, 

 whereas if these are present in living microbic or rotting leguminous 

 cells they are far more available for plant use. The best method by 

 which the nitrogen of the free air is thus made available for agricul- 

 ture is elaborated in chapters VIII and IX. 



(9) From the data now at hand I should say that the yield per 

 acre for any one of the ten principal crops whose statistics are here 

 given has probably never been either increased or diminished by 50 

 per cent of the normal yield per acre by climatic influences alone 

 over any large region, such as 100 square miles, and, further, that the 

 total annual harvest for any given crop in the United States is not 

 likely to be diminished 5 per cent by the occurrence of an inclement 

 season in some one portion of the country. 



The detailed comparison of the climate for each season with the 

 crop for that season has become practicable to me only since complet- 

 ing the table of statistics in this chapter, and it is as yet too soon to 

 anticipate all the results that will follow therefrom. 



Note. — As these statistical tables are very voluminous and only 

 extend to the year 1890 their publication has been deferred until they 

 can be brought up to date. They will probably form a continuation 

 of this present text. — C. A. 



