LEOT. iv THE FOOD OF CROPS 65 



The effect of lime upon soils may thus be described : 

 It unites with felspar or clay, setting free potash or 

 other alkalies ; it acts on vegetable matter, setting 

 free ammonia, water, nitric acid, and carbonic acid, 

 tending to destroy excess of humus (clogged or pent 

 up manure) ; and it neutralizes organic acids, thus 

 sweetening the soil, and is a plant food in itself. 



As a rule lime should only be applied to land con- 

 taining much clay or humus black soapy soil and 

 when applied it should at once be covered with earth, 

 from its tendency when brought into contact with 

 nitrogenous manures to set free ammonia. It does 

 not benefit poor land unless this is of a peaty nature. 

 A dressing of lime to old gardens over- abounding in 

 humus (vegetable matter), and therefore often sour 

 and inert, is highly advantageous if due care be 

 taken to cover the lime with soil. 



Chemical manures prove most beneficial when 

 applied early in the year, before active growth begins. 

 In fruit culture two dressings answer best, one in 

 February and another during the swelling of the fruit. 

 In both instances the manure is more speedy and 

 certain in action if applied in a liquid form, or as a 

 top dressing in showery weather. 



Never forget that throughout the season of growth, 

 crops, whether of fruit or vegetables, make incessant 

 demands upon the soil for the nourishment stored by 

 us in it. It is our duty, as it is undoubtedly to our 

 interest, to see that these stores do not become ex- 

 hausted. " Replenish," is what the whole economy 

 of plant life and soil culture is constantly saying to 

 us, and our response must be prompt. 



Manuring by Green Crops. Special attention 

 has been drawn by agricultural chemists to the fact 

 of all leguminous or pod-bearing plants, such as 

 vetches, clover, lupines, lucerne, peas and beans, obtain- 



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