FERTILIZERS AND MANURES. 51 



CHArTER IV. 



FERTILIZERS AND MANURES. 



It is the part of wisdom to return to the soil all those 

 ingredients which the plants have taken off, so that the 

 land will not become impoverished. Fertilizing, there- 

 fore, is the essential part of the gardener's duty each year. 



The substances applied to the soil for its betterment 

 may be divided into two groups: 



1. Those minerals which amend the condition of the 

 land by changing its texture, correcting its acidity and 

 otherwise modifying its condition than by the nourish- 

 ment they directly afford the plants. Such are clay, sand, 

 lime, marl, old plaster, etc., when applied to soils which 

 need them. 



2. Organic and inorganic substances which supply the 

 food for plants — such as barnyard manures and commer- 

 cial fertilizers. 



The first group may be applied at irregular, and proba- 

 bly at long intervals, in order to place the soil in the best 

 physical condition for the well-being of the plant; but 

 the second group of substances must be placed in the 

 land in small or large quantities as the needs demand, 

 each year in order to keep the fertility of the soil up to 

 its maximum condition by restoring what has been 

 extracted during each harvest. 



The ingredients most likely extracted by the growing 

 plant, in sufficient quantities to seriously affect the fer- 

 tility of the land, are phosphoric acid, potash and nitro- 

 gen. The other substances entering into the composition 

 of the plant are taken in such small amounts that the 

 effects on the soil are inappreciable even after many years 



