30 Diseases of Greenhouse Crops 



by the figure (o), and those which thrive best in 

 acid soils ( — i); beans (o), beets (3), carrots (1), 

 cauliflower (2), celery (3), cucumber (1), egg- 

 plant (2), lettuce (3), muskmelon (o), parsley (o), 

 pea, garden (1), pepper (3), radish (1), rhubarb 

 (3), sorrel (—1), spinach (3). 



Treatment of Acid Soils 



The best known remedy for soil acidity is lime. 

 Its effect is to neutralize the acidity, and to restore 

 the normal equilibrium for the activity of the soil 

 flora, thus overcoming the antagonism to normal 

 growth. The amount of lime to be used depends on 

 the kind of soil, its degree of acidity, and the crops 

 grown. It is very unlikely that injury would result 

 to greenhouse crops from the use of moderate 

 amounts of lime. Lime is sold as ground limestone 

 or as burned lime. A ton of burned limestone will 

 yield 1,120 pounds. If enough water is added, it 

 will weigh 1,480 pounds. If 1,120 pounds of 

 burned lime or the 1,480 pounds of hydrated lime 

 are allowed to air slack, the weight of both will be 

 2,000 pounds. Air slacked lime has the same com- 

 position as ground limestone. In buying hydrated 

 lime we do not get any better quality, but merely 

 pay an excess in freight for the amount of water it 

 contains. The cost of delivery should determine the 

 kind of lime to buy. 



Wood ashes may often be used instead of lime 

 to correct soil acidity. Hardwood ashes contain 

 about 30 per cent, lime and 60 per cent, potash. 



