324 SOILS 



died, decayed, and have returned to the soil. 

 From their substance have sprung other plants. 

 Each year the soil becomes richer from the return 

 of its children and is able to nourish lustier off- 

 spring. It may thus come to have upon it great 

 trees, standing so high and so thick that we won- 

 der how such a thin, rocky soil can support them. 



Then a farmer clears the land, uproots me stumps, 

 subdues the herbage, and plants corn. For a few 

 years, perhaps for many years, the crops are large; 

 but after a while they begin to dwindle. The 

 farmer then seeks to maintain his yields by ap- 

 plications of fertilisers. These help some, but 

 do not seem to restore the land to its early pro- 

 ductive power. The farmer begins to wonder 

 where the trouble lies. How can his pygmy crops 

 of grain exhaust the soil more than the great forest 

 crop of Nature's farming ? He takes a sample of his 

 soil to be analysed. The chemist tells him that 

 the soil contains enough of all the necessary plant 

 foods to grow seventy-five bushels of corn per acre 

 for several hundred years. Yet the yield has 

 fallen from sixty to forty bushels per acre, and 

 applications of fertilisers, though they increase the 

 yield considerably, do not secure the results of fifty 

 years ago. Why is this ? 



A Farmer's Logic. The farmer, and I assure 

 the reader that he is not hypothetical, then began 

 to notice more carefully the growth of crops on 

 different parts of his farm. One season he noticed 

 a bigger growth of corn in a certain spot. He 

 remembered that the thresher was set up on this 

 spot two years before and a considerable amount 

 of fine straw and chaff had remained on the ground 

 and had been plowed under. He recalled that 

 last spring the plow had pulled easier and the soil 



