SOILS AND FERTILIZERS 361 



States, but by the statistics of individual farms which have been 

 continually under the management and in the possession of the 

 same families. This shows that, so far from wearing out, these 

 soils have been steadily increasing in productivity within the per- 

 iod of which we have statistical records. This increase is due to 

 better methods of cultivation, more systematic rotation of crops, 

 more care in the selection of seed, increase of live stock, and in 

 later years to the introduction of commercial fertilizers guano, 

 from Peru, nitrate from Chile, phosphate from the United States, 

 potash from Germany ; but how much is due to each of these factors 

 can not be determined by any available records. 



Fertility of Soils Can Be Temporarily Impaired. While in 

 the foregoing it has been shown that soils do not wear out in the 

 sense that we have been accustomed to use this term and that there 

 is no general deterioration of lands, the individual can abuse his 

 soil as he can abuse his own physical powers, but in the long run, 

 even in the finite time with which we are concerned, it does not 

 affect the great problem of the general fertility of the soil. It is 

 but a detail making up the general average of national soil condi- 

 tions. 



The fertility of the farm can be temporarily impaired by im- 

 proper or careless cultivation, as in the case of cotton soils of the 

 South, where erosion is so rapid that the planter can hardly main- 

 tain from year to year the soils that he last year cultivated. And 

 what becomes of the soil that is eroded? It forms the fertile rice 

 lands of the deltas of the rivers. These are the soils from the poor 

 washed lands of the upcountry changed as to their organic matter 

 content, which they have acquired in their gradual progress down 

 the streams, and changed as a result of this organic content in their 

 physical properties, but unchanged with respect to the kind of min- 

 erals they contain. They are not and never have been exhausted of 

 plant food. With this change of state they are wonderfully produc- 

 tive. The fertility of the soils can also be temporarily impaired by 

 improper, rotation of crops as has already been shown. 



Most soils deteriorate through neglect and insufficient and in- 

 judicious cultivation. It is a general experience that soils deterior- 

 ate under tenant farmers, who have little interest in the welfare of 

 the farm beyond the year of certain occupation and little capital 

 and insufficient stock to work it with. Such cases are seen in al- 

 most all communities, where individual farms or even settlements 

 have deteriorated, while the surrounding fields under better man- 

 agement maintain their fertility. 



Soils also deteriorate even with fairly good treatment when 

 continuously cultivated in one crop, whether it be cotton, wheat, 

 corn, or tobacco. There are soils like the Marshall soils of the 

 prairie regions and the Houston and Yazoo soils of the South which 

 appear to be notable exceptions to this, but we of the United States 

 are beginning to realize very generally, what older countries have 

 known for generations, that it is neither safe nor judicious to have 



