CHAPTER III 

 SOILS 



Selection. The utmost care should be exercised in the 

 selection of soil for vegetable forcing, for however skillful 

 the grower may be, he cannot expect complete success 

 without the most favorable soil conditions. Unfor- 

 tunately, we possess very little basic information about 

 greenhouse soils, for they have not been studied to any 

 great extent by scientific investigators. Our knowledge 

 of them and their management has been deduced mainly 

 from the experiences of successful commercial growers. 



Greenhouse soils abnormal. The soils in most of the 

 greenhouses devoted to vegetable forcing and to flori- 

 culture are abnormal in structure, color, organic content, 

 and probably in chemical composition. Even the texture 

 is often modified by the addition of sand and ashes. So 

 great are the alterations in some instances that the soils 

 would not be recognized as belonging to any particular 

 classified types. The greenhouse grower strives to 

 establish the best and most perfect soil conditions, and 

 the returns usually justify the expenditure of as much 

 time and money as may be required to accomplish this. 

 His problem of soil management is radically different 

 from that of the general farmer, who may gradually im- 

 prove his land from year to year, while the greenhouse 

 grower should secure the maximum production within a 

 year or two. The glass structure over an acre of land 

 represents a large investment. This fact and the cost of 

 fuel and other operating expenses make it imperative to 

 spare no effort in providing the very best soil. 



Texture. The texture of a soil is characterized by the 

 proportion of the different-sized mineral particles which 



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