AGRICULTURE ON CLIMATE. 177 



soil. Below a certain point more elements of plant food will 

 be taken from the soil by evaporation and leaching than will 

 be returned to it 1)y plowing under the scanty crop. 



If the humus is abundant, the soil not only retains the 

 fertilizers applied by art, but also that supplied by nature, — 

 by the atmosphere, rain and snow ; but if the humus becomes 

 exhausted, the remaining barren eailh fails to retain the 

 manures applied, the fertile elements being leached through 

 and lost in the deep subsoil. Hence, above a certain point 

 in fertility the copious showers of heaven are a blessing, and 

 below that point they do but consummate the curse. 



Green manuring is nature's method of increasing the 

 fertility of the earth. The yearly return of the whole plant 

 to the soil, if it is an annual, or if a perennial, the annual 

 return of its leaves, and in time of its whole ti-unk, kept up 

 from generation to generation, produces that accumulation of 

 humus that made the virgin soil of our New England so 

 productive of the grains and grasses in earlier days, and 

 still makes the productiveness of the great prairies of the 

 West ; while, on the other hand, the leaching of the soil that 

 follows excessive cropping, coml^ined with other causes, 

 such as diminished rain-fall, dryer winds, and finally moving 

 sands, has been and is nature's method of producing that 

 utter desolation found in some portions of the Old World. 

 To a soil that hath much fertility more shall be given, and it 

 shall have abundance, and from a soil that hath little fertility 

 shall be taken away that which it hath, and it shall be poor 

 indeed. 



An indispensable element of plant growth is moisture, 

 furnished mostly by rain-fall. 



In the primitive condition of our country, the dense forests 

 were conservators of the moisture from the clouds. By their 

 roots, fallen trunks and leaves ; by the underbrush, ferns and 

 mosses growing in their shade, they retarded the flow of 

 streams, they held the water as in a sponge, and prolonged 

 the period of drainage of the melting snows and spring rains 

 cA'cn during the entire summer. But the forests having been 

 largely cut ofl*, the waters rush unckecked down the naked 

 hill and mountain sides intQ the creeks and rivers and are 

 carried off in devastating floods, to be followed by droughts, 



