SOIL EXHAUSTION AND ROTATION OF CROPS. 161 



way. You do not need a particle of organic matter in the 

 soil for the growth of any plant. Many plants have been 

 grown in simple water in which the mineral elements of the 

 plant, including nitrates, were dissolved or suspended. 



The suggestion that the result, in the case to which Mr. 

 Lawes refers, was due to the absence of vegetable matter, 

 must therefore be reo:arded as destitute of foundation. I be- 

 lieve that if he had spaded his land as deep as the roots of clo- 

 ver go, and had fertilized it well to the same depth, he would 

 have cured the clover-sickness effectually. 



The weight of evidence goes to show that this " disease" 

 is owing to the lack of nutritive material in the lower strata 

 of soil, where the long clover-roots go, and where they must find 

 nutriment. Those soils which are naturally adapted to clover 

 are those in which an equivalent to deep manuring is created 

 by the disintegration of the soil itself to a considerable depth. 



Mr. Lyman. We have instances in this county where clo- 

 ver has grown for thirty years, in deep soil. 



Mr. Gould. The soil of the Genesee wheat lands, where their 

 regular practice has been, for seventy or eighty years, to alter- 

 nate clover and wheat — wheat is their staple crop, and always 

 has been, and they always prepare for it by a crop of clover — 

 is what you would call a rich loam, mixed to a considerable 

 depth with fragments of a slaty rock. This slaty rock decora- 

 poses so rapidly as to keep the soil constantly rich, and rich to 

 a considerable depth. It does not decompose on the surface 

 rapidly enough, so that they can get a wheat crop every year, 

 but if they put on clover, and let its roots go down where there 

 are materials which the roots of the wheat plant cannot reach, 

 and bring those up to the surface, then their wheat crop runs 

 right along, and if rust or insects do not interfere with it, 

 they get a large yield every time they try it. They have two 

 years of clover and one of wheat. 



Prof. Johnson. Do they cut tlie clover entirely off? 



Mr. Gould. They do, one year. They generally have a 

 pretty good crop before they plow it in. They plow it in, 

 usually, about the first of August. 

 11 



