THE VEGETABLE GERDEN 



through the mixture. This is best done by putting 

 them in a pile in layers and then throwing them 

 into another pile. Always shovel from the bot- 

 tom of the pile, throwing the material on the top 

 of the second pile. Three or four turnings will be 

 necessary to thoroughly incorporate all the in- 

 gredients. 



All these substances which I have mentioned are 

 direct fertilisers, but there are soils from which 

 the full value of these cannot be had without the 

 use of a stimulant or indirect fertiliser. Lime and 

 land plaster or gypsum are used for this purpose. 



The reasons for the liming land are: First, 

 that sour or acid soils must be neutralised or made 

 slightly alkaline, because the bacteria which con- 

 vert the organic forms of nitrogen into the forms 

 of nitrates cannot thrive in acid soils. Second, used 

 in small quantities, it will bind loose, sandy soils. 

 Third, it will flocculate stiff clayey soils, making 

 the passage of water through them easier, lessen- 

 ing the tendency to wash, and permitting better 

 aeration. Fourth, in holding the potash compounds, 

 as already described, and overcoming the bad effect 

 of potash salts containing chlorides. 



There are other lesser reasons which it is not 

 [44] 



