THE EXPERIMENT STATIONS 



work which has already been accomplished at 

 these stations. It would be impossible to give 

 anything like an accurate estimate of the value, 

 of these stations to the nation. The aid which 

 they offer is vast in two directions, — the posi- 

 tive value, which is both direct and indirect 

 and large in both, and the negative value, 

 which is sometimes quite as important as the 

 positive. The negative importance may be 

 indicated by the words, What not to do. The 

 period of the New Earth has been so short, 

 time enough has not yet elapsed for a uni- 

 versal spread of the knowledge which has been 

 accumulating, and much left over from the 

 older order remains to be sifted, tested, 

 accepted or rejected. It is fully as important 

 sometimes to indicate what the farmer should 

 not do as to show what he should do. His 

 calling in this respect is not unlike that of 

 every other man. For example, the stations 

 have done great service by showing to farmers, 

 on analysis of their soils, that they must not 

 go on planting certain things because of the 

 soil exhaustion sure to follow such continuous 

 cropping. Again, they will be shown that cer- 

 tain fertilizers which they have long been 



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