SOIL SANITATION 277 



second crop of wheat did not thrive. It came 

 up sickly and spindling, like a child in the had 

 air of the tenements. Had this second crop 

 been part of a wheat field, the crop would 

 have been called a failure. 



Why did this second crop of wheat fail to 

 grow thriftily ? The soil contained hundreds of 

 times the amount of "plant food" necessary 

 for its growth. "Weather" conditions, that 

 prime factor, were the best. Yet it did not 

 grow. 



Repeated attempts failed to produce a sec- 

 ond crop of wheat as good as the first. The 

 soil was like a tired laborer who had worked 

 a full shift. He is incapable of continuing his 

 task with zest. So with the soil. 



Then this pot of soil was given a "change 

 of occupation." It was planted again, but 

 not to wheat this time. Instead, it was planted 

 to cow-peas. The cow-peas grew lustily ! The 

 soil that could not produce a second crop of 

 wheat produced cow-peas as thrifty as if they 

 had been grown on virgin loam under ideal 

 conditions. 



But a second crop of cow-peas was less suc- 

 cessful. It was like the second crop of wheat. 

 Wheat following wheat without intermission 



