178 BOARD OF AGRICULTURE. 



which ought to be considered in connection with these questions, 

 Mr. Gold has promised me that I shall have another hour to-mor- 

 row, and 1 will occupy this morning with a part of the subject. 



I cannot promise, however, to answer all the questions which 

 Mr. Gold has proposed. Our knowledge is not sufficient for that. 

 Mr. Gold's admission that some of his " facts may not be facts," 

 shows that investigation is needed to establish fully what is, and 

 to distinguish that from what appears to be, before we can reason- 

 ably expect to give explanations. But the very investigations 

 which shall serve in any given case to identify the fact will also 

 assist in understanding the reason of it, and in seeing clearly its 

 bearings upon the other facts which we properly regard as settled. 

 I shall endeavor then, as far as the time admits, to put before you 

 some of those considerations which seem adapted to furnish guid- 

 ing ideas in respect to my subject. 



By Exhaustion of Soil is properly understood, not a complete 

 deprivation of producing power," but simply a reduction of this 

 power below a profitable point. This is indeed a somewhat 

 indefinite definition, because the point of profit is not easy to 

 decide upon, but it is'sufficient for our purpose. 



What does exhaustion consist in ? It consists either in the 

 removal of certain materials from the soil, materials which serve 

 to feed the crop and become a part of it, and which, by continually 

 taking off harvest after harvest, become diminished in quantity, so 

 that after a certain time there is not enough left in the soil to pro- 

 duce a fair crop, or else it means that the materials which may still 

 exist in the soil no longer occur in that condition in which the crop 

 can make use of them. We may have a soil containing potash in 

 large quantities, many hundred, pounds, or tons even, in an acre, 

 taken to the depth of two or three feet ; but if this potash exist 

 there exclusively as an ingredient of some mineral which is acted 

 upon so slowly by the natural process of solution that there is no 

 available potash, as we say, nothing which the crop can get hold 

 of, such a soil would be unproductive. Again, we may have a 

 soil which contains but a thousandth part as much potash, but 

 which is fertile from the simple fact that the alkali occurs there in 

 such a state as to become available as rapidly as the crop requires 

 it. 



To cure exhaustion, we must either restore the nutritive matters 

 which have been removed from the soil, or we must change the 



