Part IL] MAINTENANCE OF SOIL FERTILITY. 45 



under glass. Something may certainly be gained by rotating 

 leguminous crops, but with land costing $2,000 an acre and 

 upward, and crops worth as much or more than that amount 

 annually, the growth of a crop merely as a nitrogen gatherer 

 is not to be thought of. 



The same general principles apply here, however, as to field 

 culture, namely, that the soil supply of nitrogen, phosphorus, 

 potassium and lime must be maintained, and that in proportion 

 as we understand and apply the principles governing the 

 economical maintenance of this supply, in that proportion will 

 be our success in crop production. 



Mr. Trout. I would like to ask the professor — he stated 

 that he lost a corn crop by plowing in the rye; would a shower 

 have saved that corn crop? 



Mr. Thorne. I think so, but we are subject to those mid- 

 summer droughts in Ohio, and it is not safe to depend on rain; 

 plowing in the rye earlier and turning the ground down would 

 have obviated the danger. 



A Member. Has the effect of nitric acid for acidity been 

 tried on other soils? 



Mr, Thorne. Yes, we have tried it on different types of 

 soil. The Ohio River is fringed by one or two hill counties and 

 much of the surface has washed away, and the underlying rock 

 is largely sand rock, although we run into the limestones. On 

 all soils of this kind we find that apparently the nitrogen is the 

 thing first needed, but the phosphorus is needed to complete the 

 fertilizer. 



A Member. Do I understand that the corn crop is inclined 

 to dislike lime? 



Mr. Thorne. The application of lime increases the corn 

 crop on an average about 8 bushels per acre. 



A Member. If you are planting corn for silage, would it 

 have the same effect? 



Mr. Thorne. Yes, it would. 



A Member. Do you consider burnt lime equal to ground 

 limestone? 



Mr. Thorne. Yes, in burning lime you burn out half of its 

 weight, and all that is of value in the lime is the calcium. 



