HOW TREES AND PLANTS IMPROVE THE LAND 91 



hay, there is still left in the land the nitrogen that was 

 stored in the roots and lower part of the stem and in the 

 fallen leaves. Even the roots and stubble of legumes, 

 therefore, can enrich the land, both in nitrogen and in 

 vegetable matter. The enrichment is much greater if the 



FIG. 58. A FIELD OF VELVET BEANS, ONE OF THE BEST SOIL-IMPROVING 



PLANTS 



tops, as well as the roots, are plowed into the soil, either 

 as soon as growth is finished or after being eaten by 

 animals pasturing on the field. 



Shall the tops of soil-improving plants be plowed into 

 the ground? The plants that most enrich the land are 

 those that make the richest hay and pasturage for horses, 

 cattle, sheep, hogs, and poultry. The farmer often asks, 

 " Does it pay better to use the vines or tops of cowpeas 

 or clover as food for live-stock or to plow them into the 



