CHAPTER 1 



THE HEALTHY SOIL 



An intelligent understanding of the soil is of para- 

 mount importance to the success of the greenhouse. 

 There are three important points that we must con- 

 sider in the study of a healthy soil. They are : ( i ) 

 texture, (2) fertilizers, (3) soil flora. 



Texture 



Texture deals with the character of the particles 

 which make up a soil, and with their arrangement 

 in relation to each other. Clay soils are generally 

 made up of very minute particles. Silt is made up 

 of large grains. Coarse sand or gravel is composed 

 of the largest grains. A soil is said to be porous 

 when air or water can circulate through it freely. 

 The porosity depends on the various proportions of 

 clay, silt and sand which that soil contains. Plant 

 growth, and incidentally plant health, is closely in- 

 terwoven with the soil structure. Compact, sticky 

 clays will be far more unfavorable to greenhouse 

 crops than a clay loam. 



The greenhouse man has the advantage over the 

 ordinary farmer because he can modify the texture 



3 



