No. 4.] SOIL EXHAUSTION. 285 



process has been going on ever since, much to the detriment 

 of the organic matter and crop-producing capacity of the 

 soil. The open fields and meadows were once rich in or- 

 ganic matter, but these have become depleted through our 

 methods of farming, which have consisted in taking every- 

 thing from the soil without making much attempt to replace 

 •what has been removed. Had the practice of plowing in 

 green crops been in vogue from the earliest times, our soil 

 would have shown much more of its primitive character, and 

 its productiveness would have been much different at the 

 present time. 



The constant depletion of organic matter which is taking 

 place in all of our soils is one of its most marked character- 

 istics at the present time, and with this decrease have come 

 inferior crops, an additional increase in certain weeds, and, 

 as already pointed out, quite marked changes in the abun- 

 dance and habitats of our native plants. It remains for us 

 to consider how these exhausted soils can be brought back 

 to a condition resembling their primitive form. It would 

 take, to be sure, some centuries to restore these soils, as 

 this would require the deposition and decomposition of an 

 immense amount of vegetable matter. Inasmuch as nature 

 has often assumed the role of teacher in other matters, we 

 may profitably turn to her guidance in considering how to 

 make our depleted soils more like those formerly existing 

 here, and consequently better adapted to support a crop. 



The most rational method that we know of at the i)i'escnt 

 time appearing to accomplish this to a certain extent is the 

 continual plowing in of green crops. This practice is by no 

 moans resoiled to as much as it should be by farmers. The 

 cultivation of cover crops and subsequent turning of them 

 under not only increases the organic matter and food con- 

 stituents of the soil, thereby giving rise to larger crops, but 

 most favorably modifies the physical conditions. Cover 

 crops also conserve soil nitrogen, and prevent, to a large 

 extent, the soil from washing during winter. A soil enriched 

 by organic matter will retain more moisture, and hence is 

 better able to withstand drought. No small compensation 

 for the trouble of green manuring consists in keeping the 

 weeds down. A field of corn sown with any crop during 



