JAMAICA. 



BULLETIN 



OF THE 



DEPARTMENT OF AURICULTURE. 



LIBRARY 



NEW VOK'K 



nOTANJCAL 



(JARUeN. 



Vol. IV. SEPTEMBER, 1906. Part 9. 



RENOVATION OF WORN-OUT SOILS." 



By W. J. SPILLMAN. 

 There is a vast difference in the natural fertility of soils. Some 

 do not produce well from the start unless special attention is 

 given to making them productive ; others produce large crops for 

 a short time and then rapidly diminish in fertility ; while others, 

 known as strong soils, remain productive for many years without 

 attention to their fertility. But even the strongest soils will wear 

 out in time unless they are intelligently managed. 



NATURE OF THE SOIL. 

 In order to understand the methods necessary for restoring worn- 

 out soils, let us consider what occurs in a fertile soil that is grow- 

 ing a large crop. Imagine a cubic inch of ordinary field soil 

 magnified into a cubic mile. It would then present very much the 

 appearance of a mass of rocks varying from the size of a pea to 

 masses several feet in diameter. Scattered among these rock 

 masses would be many pieces of decaying plant roots and other 

 organic matter, resembling rotting logs in a mass of stones and 

 gravel. The masses of organic matter would be found to contain 

 large quantities of water, and to somewhat resemble wet sponges 

 while every mass of rock would have a layer of water covering its 

 surface. The open spaces between the solid masses would be 

 filled with air. 



If a crop were growing on this soil, its roots would be found 

 threading their way among the masses of rock and decaying roots 

 and pushing these aside by the pressure exerted by the growing 

 roots. From the surface of the growing root, near its tip, small 

 3 hollow threads (the root hairs) extend into the open spaces and 

 ^ suck up the water covering the rock particles. The root hairs are 

 >- not open at the end ; they absorb the water through their walls. 

 ^ The plant food is dissolved in this water, but is usually present in 

 X 

 ->-i * Farmers' Bulletin No. 245, U. S. Dcpt. of Agriculture. 



